BioResources welcomes submission of scholarly review articles that address important issues of lignocellulosic materials usage. Preference is given to reviews that employ a lively, imaginative, and reader-friendly approach. The goal is to render technical material accessible to a wide audience of scientists who may have backgrounds in disparate fields. Review articles are subject to peer review, as in the case of research articles. Detailed formatting instructions, in addition to a 50-page length limit (not including reference section), are provided in the Author Instructions and in the review template that can be downloaded therefrom.
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Scholarly Review Articles
- Reviewpp to be addedYalcin, M. (2020). "Problems encountered in log depots and measures to combat them: A review," BioRes. 15(1), Page numbers to be added.AbstractArticlePDF
The aim of this review is to examine the problems encountered with logs kept in depots and the measures recommended to correct them. Biotic, abiotic, and other factors can affect the quality and quantitative properties of stored logs. Biotic factors include fungi (decay/rot fungi, stain fungi, and mold), insects (wood, bark, and ambrosia beetles), and bacteria. The climatic conditions of ultraviolet (UV) light, wind, and temperature at the storage site can be considered as abiotic factors. In addition, storage problems may be caused by business management, inadequate training and qualifications of depot personnel, and the type of depot floor/ground. Measures to counteract these factors were examined in detail, as a result of field observations and literature studies. The solutions presented included: shortening the storage period and expanding winter production rather than maintaining year-round storage, bringing production planning in line with the needs of the sector and providing sufficient training to workers and technical personnel, as well as increasing the sale of standing trees, separating earlier- and later-felled products in depot areas, installing pheromone traps, and ensuring proper drainage and maintenance of depot grounds. Additional measures to be taken in factory warehouses included water sprinkling and holding logs in water (ponding).
- Reviewpp to be addedHubbe, M. A., and Grigsby, W. (2020). "From nanocellulose to wood particles: A review of particle size vs. the properties of plastic composites reinforced with cellulose-based entities," BioRes. 15(1), Page numbers to be added.AbstractArticlePDF
This review article considers published evidence regarding effects of particle size on mechanical properties of plastic matrix materials filled with cellulose-based reinforcements. Cellulosic or wood-based reinforcements in plastic matrices can contribute to higher modulus, lower density, and less tendency to sag in comparison with the matrix phase by itself, while still allowing the resulting material to be cut or milled. Although cellulosic materials are generally too hydrophilic to adhere well to common thermoplastic materials such as polyethylene, such deficiencies can be overcome by use of compatibilizers, e.g. polyethylene-maleic anhydride. Recently many researchers have evaluated nanocellulose in plastic composites. The higher surface areas of nanocellulose generally imply a higher cost of compatibilizer to achieve good interfacial adhesion. This review first examines results of a large number of studies all involving high-density polyethylene as the matrix. Then, to get a more detailed mechanistic view, studies are considered that compare different particle sizes of cellulose-based reinforcements within the same conditions of preparation of composites prepared with various matrix polymers. To summarize the findings, there does not appear to be any consistent and dependable advantage of using nano-sized cellulosic reinforcements when trying to achieve higher values of composite strength or modulus.
- Reviewpp to be addedLim, S. J., Oslan, S. H., and Oslan, S. N. (2020). "Purification and characterisation of thermostable α-amylases from microbial sources," BioRes. 15(1), Page numbers to be added.AbstractArticlePDF
α-Amylases (E.C 184.108.40.206) hydrolyse starch into smaller moieties such as maltose and glucose by breaking α-1,4-glycosidic linkages. The application of α-amylases in various industries has made the large-scale productions of these enzymes crucial. Thermostable α-amylase that catalyses starch degradation at the temperatures higher than 50 °C is favourable in harsh industrial applications. Due to ease in genetic manipulation and bulk production, this enzyme is most preferably produced by microorganisms. Bacillus sp. and Escherichia coli are commonly used microbial expression hosts for α-amylases (30 to 205 kDa in molecular weight). These amylases can be purified using ultrafiltration, salt precipitation, dialysis, and column chromatography. Recently, affinity column chromatography has shown the most promising result where the recovery rate was 38 to 60% and purification up to 13.2-fold. Microbial thermostable α-amylases have the optimum temperature and pH ranging from 50 °C to 100 °C and 5.0 to 10.5, respectively. These enzymes have high specificity towards potato starch, wheat starch, amylose, and amylopectin. EDTA (1 mM) gave the highest inhibitory effect (79%), but Ca2+ (5 mM) was the most effective co-factor with 155%. This review provides insight regarding thermostable α-amylases obtained from microbial sources for industrial applications.
- Reviewpp to be addedHubbe, M. A., and Pruszynski, P. (2020). "Greaseproof paper products: A review emphasizing ecofriendly approaches," BioRes. 15(1), Page numbers to be added.AbstractArticlePDF
A cost-effective, eco-friendly, and health-promoting packaging system that prevents the passage of greases and oils would fulfill an urgent need. This review discusses what is known about the highly divergent technological paths that have been studied to achieve these objectives. Before the emergence of plastic films, the paper industry addressed these objectives in two ways, by parchmentizing and by high levels of refining of the fibers. Parchmentizing means passing the paper through a bath of concentrated sulfuric acid, followed by rinsing out the acid and drying the sheet. Though both parchmentized paper and highly refined greaseproof paper products are still made, they have been substantially displaced by oil-repellent fluorocarbon treatments of paper. The fluorocarbon treatments have allowed papermakers to achieve greaseproof properties with ordinary paper machine equipment at ordinary refining levels and without a need to immerse the paper in strong acid. Now, however, due to environmental concerns and regulations, the paper industry needs more options. Some promising directions in published research include advances in chemistry, superoleophobic surfaces, nanocellulose films, and systems to protect nanocellulose films from the effects of moisture.
- Reviewpp 10161-10184Treu, A., Zimmer, K., Brischke, C., Larnoy, E., Gobakken, L. R., Aloui, F., Cragg, S. M., Flæte, P.-O., Humar, M., Westin, M., Borges, L., and Williams, J. (2019). "Durability and protection of timber structures in marine environments in Europe: An overview," BioRes. 14(4). 10161-10184.AbstractArticlePDF
Timber structures in marine applications are often exposed to severe degradation conditions caused by mechanical loads and wood-degrading organisms. This paper presents the use of timber in marine environments in Europe from a wood protection perspective. It discusses the use of wood in coastline protection and archeological marine wood, reviews the marine borer taxa in European waters, and gives an overview of potential solutions for protection of timber in marine environments. Information was compiled from the most relevant literature sources with an emphasis on new wood protection methods; the need for research and potential solutions are discussed. Traditionally, timber has been extensively utilized in a variety of marine applications. Although there is a strong need for developing new protection systems for timber in marine applications, the research in this field has been scarce for many years. New attempts to protect timber used in marine environments in Europe have mainly focused on wood modification and the use of mechanical barriers to prevent colonization of marine wood borers. The importance of understanding the mechanisms of settlement, migration, boring, and digestion of the degrading organisms is key for developing effective systems for protecting timber in marine environments.
- Reviewpp 10093-10160Gomez-Maldonado, D., Vega Erramuspe, I. B., and Peresin, M. S. (2019). "Natural polymers as alternative adsorbents and treatment agents for water remediation," BioRes. 14(4), 10093-10160.AbstractArticlePDF
This review examines the roles of different natural polymers, composites, and nanoengineered materials that have been studied in the last 10 years for their use in water treatment. As water quality is a global concern, the use of natural and sustainable materials is fundamental to obtain high value products that can remediate water systems without generating other pollution sources or require extra energy inputs or high side costs. Filtration systems often can provide an ideal alternative to conventional water treatment. Herein the attention is focused on polysaccharides, as these can be easily obtained from green processes and can be sourced from what nowadays are considered as agricultural waste. The inherent variety of functional groups that they have provides a better interaction with certain types of pollutants. Thus, biomaterials have been harnessed to generate filtration systems and other water treatment options.
- Reviewpp 10047-10092Gowman, A. C., Picard, M. C., Lim, L.-T., Misra, M., and Mohanty, A. K. (2019). "Fruit waste valorization for biodegradable biocomposite applications: A review," BioRes. 14(4), 10047-10092.AbstractArticlePDF
Currently, food waste is a major concern for companies, governments, and consumers. One of the largest sources of food waste occurs during industrial processing, where substantial by-products are generated. Fruit processing creates a lot of these by-products, from undesirable or “ugly fruit,” to the skins, seeds, and fleshy parts of the fruits. These by-products compose up to 30% of the initial mass of fruit processed. Millions of tons of fruit wastes are generated globally from spoilage and industrial by-products, so it is essential to find alternative uses for fruit wastes to increase their value. This goal can be accomplished by processing fruit waste into fillers and incorporating them into polymeric materials. This review summarizes recent developments in technologies to incorporate fruit wastes from sources such as grape, apple, olive, banana, coconut, pineapple, and others into polymer matrices to create green composites or films. Various surface treatments of biofillers/fibers are also discussed; these treatments increase the adhesion and applicability of the fillers with various bioplastics. Lastly, a comprehensive review of sustainable and biodegradable biocomposites is presented.
- Reviewpp 7582-7626Hubbe, M. A., Azizian, S., and Douven, S. (2019). "Implications of apparent pseudo-second-order adsorption kinetics onto cellulosic materials: A review," BioRes. 14(3), 7582-7626.AbstractArticlePDF
The pseudo-second-order (PSO) kinetic model has become among the most popular ways to fit rate data for adsorption of metal ions, dyes, and other compounds from aqueous solution onto cellulose-based materials. This review first considers published evidence regarding the validity of the mechanistic assumptions underlying application of the PSO model to adsorption kinetics. A literal interpretation of the model requires an assumption that different adsorption sites on a solid substrate randomly collide with each other during a rate-limiting mechanistic step. Because of problems revealed by the literature regarding the usual assumptions associated with the PSO model, this review also considers how else to account for good fits of adsorption data to the PSO model. Studies have shown that adsorption behavior that fits the PSO model well often can be explained by diffusion-based mechanisms. Hypothetical data generated using the assumption of pseudo-first-order rate behavior has been shown to fit the PSO model very well. In light of published evidence, adsorption kinetics of cellulosic materials is expected to mainly depend on diffusion-limited processes, as affected by heterogeneous distributions of pore sizes and continual partitioning of solute species between a dissolved state and a fixed state of adsorption.
- Reviewpp 7543-7581Demuner, I. F., Colodette, J. L., Demuner, A. J., and Jardim, C. M. (2019). "Biorefinery review: Wide-reaching products through kraft lignin," BioRes. 14(3), 7543-7581.AbstractArticlePDF
This review details the structure of lignin and curates information on the characteristics that this polymer must have for each specific use. Lignin is a by-product of the pulp and paper industry and the second most abundant biopolymer after cellulose. Approximately 50 million tons of lignin are produced worldwide annually, of which 98% to 99% is incinerated to produce steam, process energy. Just 1% to 2% of the lignin, derived from the sulfite pulp industry, is used in chemical conversion to produce lignosulfonates. Biorefining is a promising approach to promote the wider use of kraft lignin. However, using kraft lignin to produce high value-added products is a great challenge, due to its complex structure, low reactivity, and low solubility, which are factors that limit the lignin’s large-scale use in biorefineries. Recent studies show that kraft lignin can be used as lignosulfonates and dispersants, technical carbons, transportation fuels, bioplastics, and adhesives, but some technological hurdles must be overcome and several industrial tests must be developed to make these uses viable.
- Reviewpp 7494-7542Zhang, H., Dou, C., Pal, L., and Hubbe, M. A. (2019). "Review of electrically conductive composites and films containing cellulosic fibers or nanocellulose," BioRes. 14(3), 7494-7542.AbstractArticlePDF
Strategic combinations of cellulosic materials with electrically conductive polymers or nanoconductors offer important potential advantages for technological advances, light-weight inexpensive products, applications of novel form factors, and more eco-friendly alternatives to certain forms of smart packaging and electronics. This review of the literature focuses on how such electrically conductive composite systems work, the roles that cellulosic materials can provide in such structures, processes by which electrically-conductive cellulose-based composites and films can be manufactured, and various potential applications that have been demonstrated. Several advantages of cellulose, such as ease of fabrication, compatibility with conductive agents, and sustainability, allow its integration with conductive agents in making conductive composites. Applications of electrically conducting cellulose-based composites for strain sensors, energy storage, solar cells, electrodes, supercapacitors, and smart packaging are discussed.
- Reviewpp 7465-7493Ülker, O. C., and Ulker, O. (2019). "Toxicity of formaldehyde, polybrominated diphenyl ethers (PBDEs) and phthalates in engineered wood products (EWPs) from the perspective of the green approach to materials: A Review," BioRes. 14(3), 7465-7493.AbstractArticlePDF
Adhesives, flame-retardant chemicals, and paints are used in engineered wood products (EWPs) to increase some of the properties of wood. Most of the engineered wood composites, including plywood, particleboard, and fiberboard, used as furniture components contain formaldehyde resins as an adhesive. The International Agency for Research on Cancer (IARC) added formaldehyde to the list of human carcinogens (Group 1) in 2004. Flame-retardant chemicals are semi-volatile organic compounds that can migrate from the products to the air. There are developmental neurotoxic effects from flame-retardant additives, among which polybrominated diphenyl ethers (PBDEs) are commonly used in EWPs. The flexibility and durability of plastics are increased using phthalates, which are a class of synthetic chemicals, by adding them to the polyvinyl chloride (PVC) that is used in the wood-plastic composites (WPC). Formaldehyde, PBDEs, and phthalates are toxicants that are commonly present in value-added furniture products. This review summarized the toxic effects of these chemicals from the aspect of human health and from the perspective of green products.
- Reviewpp 7387-7464Hubbe, M. A., Chandra, R. P., Dogu, D., and van Velzen, S. T. J. (2019). "Analytical staining of cellulosic materials: A Review," BioRes. 14(3), 7387-7464.AbstractArticlePDF
Numerous dyes and fluorescent compounds, as reported in the literature, exhibit specificity in the staining of materials associated with lignocellulosic fibers and their chemical components, including cellulose, hemicellulose, and lignin. Such effects long have provided analysts with convenient ways to identify cellulosic fiber types, products of different pulping methods, degrees of mechanical refining, estimates of accessibility to enzymes, and localization of chemical components within microscopic sections of cellulosic material. Analytical staining procedures allow for the facile estimation or quantification using simple methods such as light microscopy or UV-vis spectroscopy. More recent developments related to confocal laser micrometry, using fluorescent probes, has opened new dimensions in staining technology. The present review seeks to answer whether the affinity of certain colored compounds to certain cellulose-related domains can improve our understanding of those stained materials – either in terms of their fine-scale porous structure or their ability to accommodate certain colored compounds having suitable solubility characteristics. It is proposed here that successful staining ought to be viewed as being a three-dimensional phenomenon that depends on both the physical dimensions of the colored compounds and also on functional groups that influence their interactions with different components of lignocellulosic materials. Published information about the mechanisms of staining action as well as characteristics of different stain types is reviewed.
- Reviewpp 4996-5015Shojaeiarani, J., Bajwa, D. S., and Bajwa, S. G. (2019). "Properties of densified solid biofuels in relation to chemical composition, moisture content, and bulk density of the biomass," BioRes. 14(2), 4996-5015.AbstractArticlePDF
Global energy consumption is expected to grow by 56% between 2010 and 2040. Renewable energy is one of the fastest-growing energy resources, and biomass is a major feedstock for providing renewable energy. It constitutes up to 35% of the main energy consumption in developing countries. Densified solid biofuel with high density gets a lot of attention due to its uniform shape and low heating cost. When considering densified solid biofuels as a viable solution for energy production, its quality needs to be improved. Solid biofuel quality is a function of the chemical composition and physical properties of the raw materials. It is widely reported that the raw material chemical composition has a major effect on the final solid biofuel quality, as it influences the heating value, ash content, and mechanical durability. The moisture content influences the net heating value, combustion efficiency, and mechanical durability of solid biofuels. The bulk density influences the mechanical durability, thermal characteristics, as well as handling and storage costs of solid biofuels. This work reviewed the latest developments on the effects of the chemical composition, moisture content, and bulk density of raw materials on the thermal efficiency, emission, and mechanical durability of densified solid biofuels.
- Reviewpp 4952-4995Lindholm-Lehto, P. (2019). "Biosorption of heavy metals by lignocellulosic biomass and chemical analysis," BioRes. 14(2), 4952-4995.AbstractArticlePDF
Many types of lignocellulosic biomass show effective binding of toxic heavy metals from industrial and environmental effluents. Biosorption is an emerging option for conventional methods to remove heavy metals, some of them with even better efficiencies compared to conventional methods. Raw material for biosorption is typically low-cost and easily available, including agricultural waste or forest residues such as sawdust, bark, or needles. This review concentrates on the accumulation of heavy metals by lignocellulosic biosorbents. Thus far, biosorption has not been economically feasible on a large scale and needs further development for profitability. Industrial-scale wood-based biosorbent applications are especially still lacking. Moreover, due to legislative demands, there is an increasing need for accurate and reliable analytical methods for metal analysis of environmental and industrial effluents. In the future, biosorption processes are likely to become common, and the requirement for environmental monitoring will increase due to ever restricting regulations. This emphasizes not only the need for the development of feasible process solutions, but also a requirement for accurate analytical methods.
- Reviewpp 4902-4951Helanto, K., Matikainen, L., Talja, R., and Rojas, O. J. (2019). "Bio-based polymers for sustainable packaging and biobarriers: A critical review," BioRes. 14(2), 4902-4951.AbstractArticlePDF
Barrier materials have an important role in various packaging applications, especially considering the requirements associated with protection and shelf life. Most barrier materials used in today’s industry are either manufactured from oil resources or metals. Driven by the increase in environmental awareness, access to oil resources as well as legislation, new and environmentally benign alternatives are at the center stage of scientific and industrial interest. This article covers the use of wood-derived polymers and those produced from microorganisms, which display remarkable barrier properties. Wood-based products have received great attention for their air/oxygen resistance. As far as their properties, microorganism-derived biopolymers are comparable to conventional oil-based thermoplastics, but their cost may still be an issue. Both, wood and microorganism-derived biopolymers are challenged when moisture, grease and oxygen resistance are simultaneously required. Hence, multilayer structures and composites are needed to fulfill the most demanding requirements of packaging materials. Here we offer a review of these topics together with a discussion of their prospects.
- Reviewpp 4873-4901Teaca, C.-A., Roşu, D., Mustaţă, F., Rusu, T., Roşu, L., Roşca, I., and Varganici, C. D. (2019). "Natural bio-based products for wood coating and protection against degradation: A Review," BioRes. 14(2), 4873-4901.AbstractArticlePDF
Preservation of wood structures against degradation represents an old, and however, a new challenge. Wood, as a natural hybrid composite material, represents a versatile and widely exploited renewable resource for indoor and outdoor applications. Its constitutive biopolymers are subjected to intense and progressive oxidative degradation processes under environmental conditions of exposure, affecting wood’s native durability and generating significant structural and color changes, along with progressive diminution of its resistance against biological agents. One effective way to prevent wood degradation is to apply coating protective layers by chemical modification of the surface. In this context, increasing interest for improving wood coatings behavior under exposure to outdoor applications, when these are able to prevent or limit to a large extent the deleterious effects of environmental factors upon their performance, justifies enhanced research efforts to provide new effective solutions for sustainable wood protection. Recent trends in this area include use of bio-based natural products – extractives, oils, waxes, resins, biopolymers, biological control agents – for which the main classification criterion is represented by the type of protection provided, considering the large available variety of such formulations. The present paper focuses on the most recent literature data with significant assessment of specific topics related to these issues.
- Reviewpp 2420-2457Téllez-Téllez, M., and Diaz-Godinez, G. (2019). "Omic tools to study enzyme production from fungi in the Pleurotus genus," BioRes. 14(1), 2420-2457.AbstractArticlePDF
Fungi from the Pleurotus genus secrete different enzymes, including laccases, manganese peroxidases, versatile peroxidases, glycosyl hydrolases, peptidases, and esterases/lipases. This genus contains white-rot fungi, which degrade the components of plant materials. The secreted enzymes have great application in the biotechnology field. The general conditions of a fungal culture have a direct effect on the regulation of protein expression, which changes the composition of the transcriptome, proteome, and secretome. Studies have shown that the culture type, either solid or submerged, also changes the transcriptional profiles. The knowledge of the transcriptome and proteome allows one to find valuable enzymes to obtain portable fuels from lignocellulosic materials and provide information oriented to improve the enzymes production through different culture conditions. Additionally, research has been conducted on the Pleurotus genus to better understand its biology. Numerous tools have been used for this purpose, such as classical recombination, genetic engineering, and omic tools. The information generated by the omic sciences (comparative genomics, transcriptomics, proteomics, and metabolomics) and through bioinformatics (massive data analysis), among other things, can greatly contribute to improving production processes and the use of metabolites. This review discussed some works where omic tools have been used to study enzyme production of fungi of the Pleurotus genus.
- Reviewpp 2389-2419Pelton, R. H., Yang, D., and Gustafsson, E. (2019). "Polymers that strengthen never-dried joints between wet cellulose surfaces – A review," BioRes. 14(1), 2389-2419.AbstractArticlePDF
Forming an adhesive joint between two wet cellulose surfaces before a drying step is important when manufacturing paper, foams, aerogels, other novel materials from wood pulp fibers, and various types of nanocellulose. This paper reviews the literature with an emphasis on the role of adhesive polymers on wet cellulose adhesion. Linkages between the organization of adhesives between the bonded surfaces and the strength of joints are emphasized. Relevant adhesion results from the surface forces apparatus, colloidal probe atomic force microscopy, paper wet-web strength, and wet-peeling of laminated regenerated cellulose membranes are considered.
- Reviewpp 2352-2388Nasir, S., Hussein, M. Z., Zainal, Z., Yusof, N. A., Mohd Zobir, S. A., and Alibe, I. M. (2019). "Potential valorization of by-product materials from oil palm: A review of alternative and sustainable carbon sources for carbon-based nanomaterials synthesis," BioRes. 14(1), 2352-2388.AbstractArticlePDF
The crises in global energy and environmental degradation, combined with developing consumer demands have stimulated researchers’ interest in inexpensive, environmentally friendly functional materials. Based on a projected annual production of palm oil in Malaysia of over 15.4 million metric tons by 2020, it is estimated that about 46.6 tons of lignocellulosic wastes will be generated. Transforming these wastes into wealth could be integrated into a global paradigm shift towards sustainable development. Carbon-based nanomaterials including graphene, graphene oxide, carbon nanotubes, epoxy nanocomposites, porous carbon nanoparticles, and nanoactivated carbons-filled-epoxy nanocomposites have been produced from these by-product materials using methods such as vapour deposition, pyrolysis, hydrolysis, chemical composition, high energy ball milling, and solution casting. This review attempts to present the current developments on renewable carbon nanomaterials derived from oil palm-based precursors with some insights given on their potential applications as energy storage materials.
- Reviewpp 2300-2351Hubbe, M., Alén, R., Paleologou, M., Kannangara, M., and Kihlman, J. (2019). "Lignin recovery from spent alkaline pulping liquors using acidification, membrane separation, and related processing steps: A Review," BioRes. 14(1), 2300-2351.AbstractArticlePDF
The separation of lignin from the black liquor generated during alkaline pulping is reviewed in this article with an emphasis on chemistry. Based on published accounts, the precipitation of lignin from spent pulping liquor by addition of acids can be understood based on dissociation equilibria of weak acid groups, which affects the solubility behavior of lignin-related chemical species. Solubility issues also govern lignin separation technologies based on ultrafiltration membranes; reduction in membrane permeability is often affected by conditions leading to decreased solubility of lignin decomposition products and the presence of colloidal matter. Advances in understanding of such phenomena have potential to enable higher-value uses of black liquor components, including biorefinery options, alternative ways to recover the chemicals used to cook pulp, and debottlenecking of kraft recovery processes.
- Reviewpp 2287-2299Lopes, D. J. V., Stokes, E. C., and dos Santos Bobadilha, G. (2019). "The use of chemical and biological agents in the recovery of heavy metals from treated woods – A brief review," BioRes. 14(1), 2287-2299.AbstractArticlePDF
This manuscript provides a brief review about chemical and biological agents used to bioremediate treated wood waste. Wood preservatives have been used to increase wood’s useful life, because any species is subject to decay. Studies indicate that the disposal of treated wood after its service has drawn concern and scrutiny. Practices have included disposal in landfills or construction sites as well as destruction by burning, so it is apparent that more environmentally friendly options are needed. To mitigate these problems, acidic agents, fungi, and bacteria can be used as alternatives to remove heavy metals. At optimum temperature and concentration, acids play a major role in the removal process. The process is enhanced when a bioremediation technique is used after chemical extraction. In fact, bioremediation has been shown to be a remarkable technique for recovering copper, arsenic, creosote, and other compounds. The major drawback is the extensive duration of fungal activity for release of heavy metals.
- Reviewpp 9220-9252Teng, T.-J., Mat Arip, M. N., Sudesh, K., Nemoikina, A., Jalaludin, Z., Ng, E.-P., and Lee, H.-L. (2018). "Conventional technology and nanotechnology in wood preservation: A Review," BioRes. 13(4), 9220-9252.AbstractArticlePDF
Wood products are usually treated with wood preservatives to protect them from deterioration. Pressure or non-pressure preservative treatments can be utilized to incorporate biocide into the wood, depending on the applications of the end-products. Thermal and chemical modifications of wood represent alternative treatments that enhance the dimensional properties of wood and provide biological resistance. However, there is also a current trend to apply nanotechnology for wood preservation. Nanomaterials with unique properties can enhance the performance of wood preservatives, thereby increasing the service lifetime of the wood products. Nanotechnology can be applied for this purpose through impregnation of wood with a suspension of metallic nanoparticles, or through encapsulation of biocide with nanocarriers. Additionally, various nanomaterials also can be used in wood modification, especially coating treatment to provide superior service ability. Nevertheless, more studies are required to provide guidelines regarding the safety upon application of nanomaterials. This review will give an overview of current wood preservation techniques. Additionally, this paper examines current research on how nanotechnology is being applied for wood preservation.
- Reviewpp 9180-9219Hubbe, M. A., Becheleni, E. M. A., Lewis, A. E., Peters, E. M., Gan, W., Nong, G., Mandal, S., and Shi, S. Q. (2018). "Recovery of inorganic compounds from spent alkaline pulping liquor by eutectic freeze crystallization and supporting unit operations: A Review," BioRes. 13(4), 9180-9219.AbstractArticlePDF
After the kraft or soda pulping of lignocellulosic materials to produce pulp suitable for papermaking, the spent pulping liquor typically has been recovered by multi-effect evaporation, followed by incineration in a recovery boiler. This review article considers one unit operation, eutectic freeze crystallization (EFC), that may have potential to save some of the energy that is presently consumed in the evaporation step during recovery of inorganic chemicals from spent pulping liquor. Based on a review of the literature it appears that EFC can be employed to obtain relatively pure sodium sulfate and sodium carbonate, along with relatively pure water (in the form of ice) from the spent liquor, under the assumption that lignin previously has been removed by acidification and precipitation. Issues of inorganic scale formation, during the operation of an EFC process applied to lignin-free black liquor, will require research attention. The chemical reactions to regenerate the active pulping chemicals sodium hydroxide and sodium sulfide from sodium carbonate, sodium sulfate, and other compounds isolated by EFC can be carried out either in a separate operation or by returning the materials to the feed of an existing recovery boiler.
- Reviewpp 9158-9179Londoño Zuluaga, C., Du, J., Chang, H. M., Jameel, H., and Gonzalez, R. (2018). "Lignin modifications and perspectives towards applications of phenolic foams: A Review," BioRes. 13(4), 9158-9179.AbstractArticlePDF
Lignin is a complex natural polymer and by-product of the pulp and paper industry. Currently, the increasing interest in bio-based products has motivated the search for alternative renewable feedstocks that can sustainably replace synthetic polymers. Because of the phenolic functionalities of lignin, this natural polymer has attracted interest for application in biomaterials. Among various products, polymeric foams stand out as a potential product in which lignin incorporation has resulted in improved mechanical and thermal properties. This paper reviews the state of lignin foam development, with emphasis placed on phenol-lignin types.
- Reviewpp 7155-7171Akgul, A., and Akgul, A. (2018). "Mycoremediation of copper: Exploring the metal tolerance of brown rot fungi," BioRes. 13(3), 7155-7171.AbstractArticlePDF
In recent decades, fungal roles in bioremediation of toxic contaminants such as potentially toxic elements (PTEs) residing in soil, waste water, and landfills have been studied. Bioremediation is an alternative way to deal with toxic contaminants in the environment. Some decay fungi are able to remove metals by producing metabolites, such as oxalate, which can react with metal ions and generate insoluble forms of metal:crystal complexes. Brown-rot fungi have the ability to produce extracellular oxalate in significant amounts, and this is closely related to chelation of copper by precipitating to copper oxalate crystals. Copper-tolerant brown-rot fungi have a potential role in a bioremediation system by depolymerizing the structure of wood treated with copper-based wood preservatives and adapting to copper through increased oxalate production and formation of copper oxalate crystals. The focus of this review is to suggest that copper-tolerant brown-rot fungi could be a viable option for use in future mycoremediation practices.
- Reviewpp 7137-7154Zhang, J., Wang, T., Tang, X., Peng, L., Wei, J., and Lin, L. (2018). "Methods in the synthesis and conversion of 2,5-Bis-(hydroxylmethyl)furan from bio-derived 5-hydroxymethylfurfural and its great potential in polymerization," BioRes. 13(3), 7137-7154.AbstractArticlePDF
To meet increasing demands for alternatives to fossil-based chemicals, environment-friendly and renewable energy materials are of great importance. Biomass-derived 2,5-bis-(hydroxylmethyl)furan (BHMF) has the potential to partly substitute petroleum-based aromatic diols during polymerization. This paper summarizes recent research on the synthesis of BHMF by the reaction of hydrogen from biomass-based 5-hydroxymethylfurfural through different reduction routes, including the Cannizzaro reaction, catalytic hydrogenation, and catalytic transfer hydrogenation. Applications of BHMF as a direct material and intermediate in fabricating polyurethane, self-healing materials, resins, and more, which utilize ring-opening, double-bond addition, and oxidation reactions, are discussed briefly. Additionally, the challenges and opportunities in the formation and application of BHMF in the future are discussed.
- Reviewpp 7096-7136Hubbe, M. A., Henniges, U., Potthast, A., Ahn, K., and Smith, R. (2018). "Nonaqueous solution deacidification treatments to prolong the storage life of acidic books: A review of mechanistic and process aspects," BioRes. 13(3), 7096-7136.AbstractArticlePDF
According to published studies, certain nonaqueous solution-based treatments can be highly effective for prolonging the useful lives of bound volumes, within which the paper had been formed under acidic papermaking conditions. Such treatments, which typically use reactive alkoxide-based organometallic compounds dissolved in low-surface-tension liquids, have been shown to decrease the tendency of the paper to become brittle during long storage or during accelerated aging. This article reviews published evidence concerning the underlying mechanisms of such treatments. Evidence suggests that dissolved alkoxides and related carbonated alkoxide-based compounds are able to react directly with acidic species within acidic paper during treatment of books. Such reactions help explain the demonstrated effectiveness of nonaqueous solution-based deacidification treatments.
- Reviewpp 4728-4769Teaca, C., Tanasa, F., and Zanoaga, M. (2018). "Multi-component polymer systems comprising wood as bio-based component and thermoplastic polymer matrices – An overview," BioRes. 13(2). 4728-4769.AbstractArticlePDF
The production of wood-based polymer composites has gained increasing interest in recent years, especially regarding sustainability issues, aiming at the recovery, reuse, and up-cycling of by-products from natural resources exploitation, as well as plastics. Due to their reduced cost, low density, and availability, wood components (fibers, flour) are attractive fillers for thermoplastic polymer matrices used in multi-component systems. Performance of wood-based thermoplastic materials mainly depends on the type and strength of interactions at the polymer-wood interface. Different low polarity polymers (high/low density polyethylene, polypropylene, polyvinylchloride) can be successfully used as matrices in such formulations. Various methods may be applied in order to obtain specified performance attributes of wood-based composites. Addition of appropriate compatibilizing agents, chemical and/or physical modification of the filler in order to improve its compatibility towards the matrix, or a judicious combination of these approaches may be employed. This paper briefly reviews some recent literature data, as well as research results by the authors, aiming at a comparative assessment of the materials properties (structure, thermal, mechanical and water sorption behavior) in correlation with the nature and type of components, processing, recycling options, and environmental impact.
- Reviewpp 4630-4727Nelson, L., Park, S., and Hubbe, M. A. (2018). "Thermal depolymerization of biomass with emphasis on gasifier design and best method for catalytic hot gas conditioning," BioRes. 13(2), 4630-4727.AbstractArticlePDF
This paper reviews ways that biomass can be converted by thermal depolymerization to make synthetic gas, i.e. syngas. Biomass, being carbon neutral, is considered as a form of solar energy stored during the growing season by photosynthesis. An effective biomass is one with low moisture and ash content, high lignin content, high calorific value, and small particle size. Woody biomass with low ash content (<1%), nut shells with high lignin content (30 to 40%), and municipal solid waste with synthetic polymers are effective at creating value-added synthetic gases. An allothermal downdraft gasifier produces a low tar syngas (99.9% tar conversion) at 850 oC and provides a simple and low-cost process. Integrated gasification combined cycle (IGCC) improves thermodynamic efficiency. To avoid thermal loss, a hot gas filtration system uses trona sorption material for sulfur and halogen compounds. Secondary systems can use multiple cyclones followed by reactors employing calcined dolomite, olivine, and others for adsorption or reaction with residual sulfur, ammonia, metals, and halogens. Reforming of residual tar to syngas can take place within chambers with ceramic tubes doped with nano-nickel particles. Syngas can then be used in boilers, gas turbines for production of electricity or production of chemicals by Fischer-Tropsch conversion.
- Reviewpp 4593-4629de Assis, T., Reisinger, L. W., Pal, L., Pawlak, J., Jameel, H., and Gonzalez, R. W. (2018). "Understanding the effect of machine technology and cellulosic fibers on tissue properties – A Review," BioRes. 13(2), 4593-4629.AbstractArticlePDF
Hygiene tissue paper properties are a function of fiber type, chemical additives, and machine technology. This review presents a comprehensive and systematic discussion about the effects of the type of fiber and machine technology on tissue properties. Advanced technologies, such as through-air drying, produce tissue with high bulk, softness, and absorbency. Conventional technologies, where wet pressing is used to partially dewater the paper web, produces tissue with higher density, lower absorbency, and softness. Different fiber types coming from various pulping and recycling processes are used for tissue manufacturing. Softwoods are mainly used as a source of reinforcement, while hardwoods provide softness and a velvet type surface feel. Non-wood biomass may have properties similar to hardwoods and/or softwoods, depending on the species. Mechanical pulps having stiffer fibers result in bulkier papers. Chemical pulps have flexible fibers resulting in better bonding ability and softness. Virgin fibers are more flexible and produce stronger and softer tissue. Recycled fibers are stiffer with lower bonding ability, yielding products that are weaker and less soft. Mild mechanical refining is used to improve limitations found in recycled fibers and to develop properties in virgin fibers. At the same time that refining increases strength, it also decreases bulk and water absorbency.
- Reviewpp 4577-4592Zhang, S., Chen, C., Duan, C., Hu, H., Li, H., Li, J., Liu, Y., Ma, X., Stavik, J., and Ni, Y. (2018). "Regenerated cellulose by the Lyocell process, a brief review of the process and properties," BioRes. 13(2). 4577-4592.AbstractArticlePDF
Lyocell fiber has emerged as an important class of regenerated cellulose that is produced based on the N-methyl morpholine-N-oxide (NMMO) dissolution method, and it has unique properties compared to viscose fiber. The NMMO technology provides a simple, resource-conserving, and environmentally friendly method for producing regenerated cellulose fiber. In this paper, the manufacturing process, environmental impact, and product quality of lyocell fiber are reviewed and compared with those of the conventional viscose fiber.
- Reviewpp 4550-4576Su, Y., Yang, B., Liu, J., Sun, B., Cao, C., Zou, X., Lutes, R., and He, Z. (2018). "Prospects for replacement of some plastics in packaging with lignocellulose materials: A brief review," BioRes. 13(2), 4550-4576.AbstractArticlePDF
There has been increasing concern regarding environmental problems arising from the widespread use of petroleum-based plastic materials for packaging. Many efforts have been made to develop sustainable and biodegradable packaging materials to replace plastic products. The current review summarizes recent research progress in developing cellulose packaging materials to replace plastics used for cushioning and barrier packaging functions based on pulp fibers, cellulose nanofibers, and regenerated cellulose films to benefit from their renewability, sustainability and biodegradability. The cushioning packaging materials include molded pulp products and bio-based foams. Advanced cellulose films and paper can be good barriers for oxygen and carbon dioxide gases, as well as for water vapor. Several cellulose fiber-based packaging products have been commercialized in areas that used to be occupied solely by plastic products.
- Reviewpp 2171-2181Yang, L., and Liu, H. (2018). "A review of Eucalyptus wood collapse and its control during drying," BioRes. 13(1), 2171-2181.AbstractArticlePDF
The relevant literature is reviewed concerning eucalyptus wood collapse, with a focus on lumber drying technology. Potential future research is summarized regarding where potential future work may focus. Eucalyptus is often limited as a solid wood products material due to microstructural collapse and interior cracking that may occur during drying. To prevent the drying collapse, studies have focused on the mechanism of collapse, the morphological characteristics of collapse, the control of collapse, amongst other criteria. Because the surface tension of water results in wood cell collapse, the shape of collapsed cells should be recovered after the liquid tension disappears. Therefore, pretreating green timber (such as pre-heating, pre-steaming, microwave treatment, pre-freezing, or boiling) prior to drying results in the modification of wood cell tissue and inhibits the conditions for collapse. Thus, there is improved wood permeability, drying rate, shortened drying time, as well as reduced collapse during the drying process. In addition, applying process control in regards to a suitable drying schedule (especially the drying temperature), relative humidity, drying time, intermittent drying process, combined drying technology, etc., tends to reduce the amount of collapse and improve drying quality. Reconditioning, such as steaming during the drying process, can aid collapse recovery. Generally, reconditioning or other treatment can help recover 50% of the collapse.
- Reviewpp 2150-2170Xu, Y., Li, S., Yue, X., and Lu, W. (2018). "Review of silver nanoparticles (AgNPs)-cellulose antibacterial composites," BioRes. 13(1), 2150-2170.AbstractArticlePDF
With the improvement of living standards, the human demand for antibacterial materials has increased. Cellulose, as the most abundant polymer in the world, is natural, biodegradable, and renewable, which makes it a promising raw material for the production of antibacterial materials. Silver nanoparticles (AgNPs)-cellulose antibacterial composites exhibit good biocompatibility and antimicrobial properties. These materials are easily degraded chemically and are environmentally friendly. Therefore, the AgNPs-cellulose antibacterial composites exhibit broad utilization prospects in environmental protection, medicine, chemical catalysis, and other fields. Several methods are used to manufacture such materials. This paper reviews three common techniques: the physical method, the in situ chemical reduction method, and the covalent bonding method. The differences and relationships are identified, and the advantages and disadvantages are compared among these three methods. Lastly, the present situation and the development potential of the AgNPs-cellulose antibacterial composites are discussed in this review.
- Reviewpp 2139-2149Wei, W., Li, Y., Xue, T., Tao, S., Mei, C., Zhou, W., Wang, J., and Wang, T. (2018). "The research progress of machining mechanisms in milling wood-based materials," BioRes. 13(1), 2139-2149.AbstractArticlePDF
The machining mechanisms in milling for medium-density fiberboard (MDF) and wood-plastic composites (WPC) are reviewed in this article. The study focuses on milling tool wear, chip formation mechanisms, processing stability, and machined surface roughness. The influence law of cutting parameters (cutting speed, feed rate, and cutting thickness), tool materials and geometry (rake angle, relief angle, and size parameters), temperature, and other factors on tool wear and machined surface roughness were considered. Concrete measures to improve tool life and machined surface quality are summarized as well as an online monitoring system of tool wear and machined surface roughness. Future research of tool wear and surface quality in milling wood-based materials is proposed to provide important references for wood-based materials researchers.
- Reviewpp 2116-2138Cogulet, A., Blanchet, P., and Landry, V. (2018). "The multifactorial aspect of wood weathering: A review based on a holistic approach of wood degradation protected by clear coating," BioRes. 13(1), 2116-2138.AbstractArticlePDF
Wood is an abundant and renewable natural resource. Its use is promoted as a way to reduce the carbon footprint in building construction. Wood structures are degraded by their environment due to weathering. This review is a meta-analysis of the main factors of degradation that belong to this phenomenon. The impact of irradiation, the role of water, oxygen, temperature, and colonization by fungi are explained. To protect against these factors, the use of coatings is the most common solution. Since currently the trend is to maintain the grain and the natural color of the wood, the use of transparent coatings is favored. This review presents the main technologies used in clear wood coatings. The durability of this protection against weathering is approached. The whole of knowledge gathered has made it possible to begin a discussion on the multifactorial aspect of wood weathering. Schemes were created to synthesize the synergistic and antagonistic effects between the degradation factors.
- Reviewpp 2049-2115Hubbe, M., Pizzi, A., Zhang, H., and Halis, R. (2018). "Critical links governing performance of self-binding and natural binders for hot-pressed reconstituted lignocellulosic board without added formaldehyde: A review," BioRes. 13(1), 2049-2115.AbstractArticlePDF
The production of fiberboard, particleboard, and related hot-pressed biomass products can convert small, relatively low-valued pieces of wood into valuable products. There is strong interest in being able to manufacture such products without the addition of formaldehyde, which is a health hazard during both production and use. This article reviews literature describing various challenges that need to be faced in order to achieve satisfactory bonding properties in hot-pressed bio-based board products without the addition of formaldehyde. Bonding mechanisms are examined in the form of a hypothesis, in which the strength development is represented by a chain with four links. Failure of a board is expected to occur at the weakest of these mechanistic links, which include mechanical contact, molecular-scale wetting and contact, various chemical-based linkages, and structural integrity. The most promising technologies for environmentally friendly production of hot-pressed board with use of lignocellulosic materials tend to be those that favor success in the development of at least three of the mechanistic links in the hypothetical chain.
- Reviewpp 9556-9661Hubbe, M. A., Tayeb, P., Joyce, M., Tyagi, P., Kehoe, M., Dimic-Misic, K., and Pal, L. (2017). "Rheology of nanocellulose-rich aqueous suspensions: A Review," BioRes. 12(4), 9556-9661.AbstractArticlePDF
The flow characteristics of dilute aqueous suspensions of cellulose nanocrystals (CNC), nanofibrillated cellulose (NFC), and related products in dilute aqueous suspensions could be of great importance for many emerging applications. This review article considers publications dealing with the rheology of nanocellulose aqueous suspensions in the absence of matrix materials. In other words, the focus is on systems in which the cellulosic particles themselves – dependent on their morphology and the interactive forces between them – largely govern the observed rheological effects. Substantial progress in understanding rheological phenomena is evident in the large volume of recent publications dealing with such issues including the effects of flow history, stratification of solid and fluid layers during testing, entanglement of nanocellulose particles, and the variation of inter-particle forces by changing the pH or salt concentrations, among other factors. Better quantification of particle shape and particle-to-particle interactions may provide advances in future understanding. Despite the very complex morphology of highly fibrillated cellulosic nanomaterials, progress is being made in understanding their rheology, which supports their usage in applications such as coating, thickening, and 3D printing.
- Reviewpp 9538-9555Ghiyasinasab, M., Lehoux, N., and Ménard, S. (2017). "Production phases and market for timber gridshell structures: A state-of-the-art review," BioRes. 12(4), 9538-9555.AbstractArticlePDF
Timber gridshell is a structure with a doubly curved shape that is made of grid timber laths. Gridshell structure can be a solution of interest in modern free-form structures that are environmentally sustainable. However, there is a lack of academic research focusing on the potential markets and the production stages based on this construction technology. The aim of this literature review is to investigate the gridshell structure to identify its global production process, as well as the partners involved in the architectural examples studied. A review of both peer-reviewed scientific articles and grey literature resources (e.g., magazines, web pages, etc.) was conducted to gather information about timber gridshells. The design examples found were categorized as small, medium, and large gridshells. The categorization is based on the size and level of complexity of the design examples. Production phases and partners involved in the design and construction of these structures were identified for each category. Furthermore, the motivations and barriers to using gridshell designs in construction, and the potential market segments were determined.
- Reviewpp 9520-9537McDonald, J. D., and Kerekes, R. (2017). "Pragmatic mathematical models of wet pressing in papermaking," BioResources, 12(4), 9520-9537.AbstractArticlePDF
This paper compares mathematical models developed over the years to estimate the moisture content of paper after wet pressing on paper machines. Models that assume all loading pressure to act upon water are discussed in detail. In contrast, most conventional models assume that pressure splits between a hydraulic component causing water removal and a structural component supported by the fibres. This assumption is shown to be questionable in light of theoretical considerations and experimental evidence. Despite their simpler nature, models based on hydraulic forces alone are often better able to account for experimental observations. The Decreasing Permeability (DP) model is the most complete model of this form and includes all major variables affecting pressing on paper machines, thereby enabling evaluation of key factors such as the relative importance of dewatering under flow-controlled and pressure-controlled conditions together with rewetting.
- Reviewpp 9502-9519Razali, N., Hameed Sultan, M. T., and Jawaid, M. (2017). "A Review on detecting and characterizing damage mechanisms of synthetic and natural fiber based composites," BioRes. 12(4), 9502-9519.AbstractArticlePDF
The damage to composite structures caused by impact events is one of the most critical behaviors that inhibit the widespread application of composite material. As the application of synthetic and natural based composite material increases over time, improved knowledge of composite damage in areas such as automotive and aerospace is exceedingly necessary. It is important to study and understand the damage mechanism of composite structures to produce effective designs. The failure caused by damage in structural design can result in unintended consequences. Extensive research has been conducted to detect impact damage in synthetic fiber. There are various methods to identify and characterize the damage. This article provides a comprehensive review of recent literature focusing on the broader scope of impact damage and incipient thermal damage of synthetic and natural fiber-based composites. In this report, the available research is reviewed by considering all aspects related to damage in composite materials, particularly the work done on detecting and characterizing damage mechanisms of synthetic and natural fiber-based composites.
- Reviewpp 2234-2248Hu, Z., Tang, C,. He, Z., Lin, J., and Ni, Y. (2017). "1-methylcyclopropene (MCP)-containing cellulose paper packaging for fresh fruit and vegetable preservation: A review," BioRes. 12(1), 2234-2248.AbstractArticlePDF
The freshness and safety of fruits and vegetables is important in our daily life. Paper products are often used for shipping, wrapping, and decoration in the retail for fruits and vegetables. When these paper products are modified with active substances, they can offer additional functions other than just packaging. Thus, introducing 1-methylcyclopropene (1-MCP) into paper products can impart a preservation function for fruits and vegetables. 1-MCP is an excellent and eco-friendly inhibitor of ethylene that can effectively retard the ripening of fruits and vegetables. This article reviews the ripening process induced by ethylene, the inhibition mechanism of 1-MCP, and the existing technologies and products for 1-MCP utilization. Novel active paper packaging products via the use of encapsulated 1-MCP complexes may have a great potential for commercialization. Such packaging containing 1-MCP active paper could be effective in prolonging the shelf-life and improving the quality of the product during the storage, shipping process, and retail market, and can be attractive economically, socially, and environmentally.
- Reviewpp 2143-2233Hubbe, M. A., Ferrer, A., Tyagi, P., Yin, Y., Salas, C., Pal, L., and Rojas, O. J. (2017). "Nanocellulose in thin films, coatings, and plies for packaging applications: A review," BioRes. 12(1), 2143-2233.AbstractArticlePDF
This review article was prompted by a remarkable growth in the number of scientific publications dealing with the use of nanocellulose (especially nanofibrillated cellulose (NFC), cellulose nanocrystals (CNC), and bacterial cellulose (BC)) to enhance the barrier properties and other performance attributes of new generations of packaging products. Recent research has confirmed and extended what is known about oxygen barrier and water vapor transmission performance, strength properties, and the susceptibility of nanocellulose-based films and coatings to the presence of humidity or moisture. Recent research also points to various promising strategies to prepare ecologically-friendly packaging materials, taking advantage of nanocellulose-based layers, to compete in an arena that has long been dominated by synthetic plastics. Some promising approaches entail usage of multiple layers of different materials or additives such as waxes, high-aspect ratio nano-clays, and surface-active compounds in addition to the nanocellulose material. While various high-end applications may be achieved by chemical derivatization or grafting of the nanocellulose, the current trends in research suggest that high-volume implementation will likely incorporate water-based formulations, which may include water-based dispersions or emulsions, depending on the end-uses.
- Reviewpp 2125-2142Zhao, J., and Kerekes, R. (2017). "A historical perspective of scientific advances in paper forming hydrodynamics: 1950-2000," BioRes. 12(1), 2125-2142.AbstractArticlePDFThis paper reviews key advances in understanding the hydrodynamics of the forming section of papermaking during the years 1950 to 2000. Over this period papermaking advanced from rather slow-speed Fourdrinier machines to modern high-speed twin-wire formers. The advances are described in the context of technical problems faced at the time to increase machine speeds and improve paper properties. The scientific work and advances in machine design contributed greatly to the marvel of modern papermaking, which now includes machines 10 m wide operating at speeds over 100 km/h.
- Reviewpp 2108-2124Rezania, S., Md Din, M. F., Eva Mohamad, S., Sohaili, J., Mat Taib, S., Mohd Yusof, M. B., Kamyab, H., Darajeh, N., and Ahsan, A. (2017). "Review on pretreatment methods and ethanol production from cellulosic water hyacinth," BioRes. 12(1), 2108-2124.AbstractArticlePDFLignocellulosic biomass resources are renewable materials that can be converted to fermentable sugars and subsequently into ethanol. Water hyacinth (Eichhornia crassipes) is a cellulosic aquatic plant that has high carbohydrates, low lignin content, and notable reducing sugars content in its structure. Based on the literature review in the case of water hyacinth, the most frequently used pretreatment methods were acid and alkali, while ionic liquid and microwave-assisted methods were used rarely. The dominant sugars were glucose, xylose, galactose, arabinose, and mannose. Based on the findings, cellulase and S. cerevisiae were mostly used for enzymatic hydrolysis and fermentation of water hyacinth to ethanol, respectively. This review presents the recent studies in pretreatment, hydrolysis, and fermentation of water hyacinth biomass into ethanol.
- Reviewpp 2081-2107Brännvall, E. (2017). "The limits of delignification in kraft cooking," BioRes. 12(1), 2081-2107.AbstractArticlePDFThe perspective of the article is to explore kraft cooking at the limits of delignification, i.e. what degree of delignification is needed to obtain fibre liberation and what is the maximum degree of delignification possible in the kraft pulping stage. The reasons for the quite narrow boundaries for sufficient and maximum delignification are explained, and the differences between the behaviour of hardwood and softwood kraft pulping are clarified.
- Reviewpp 2058-2080Vallejos, M. E., Felissia, F. E., and Area, M. C. (2017). "Hydrothermal treatments applied to agro- and forest-industrial waste to produce high added-value compounds," BioRes. 12(1), 2058-2080.AbstractArticlePDF
Agro- and forest-industrial wastes are abundant and low cost sources of carbohydrates and phenolic compounds, which can be converted into biofuels, biomaterials, and high added-value compounds by different pathways in small and large biorefineries. The development of technologies based on hydrothermal treatments could improve the utilization of lignocellulosic wastes through the separation of its components (cellulose, hemicellulose, lignin, and extractives) in sequential processes. The adopted technologies for the separation and conversion of these lignocellulosic wastes into synthesis intermediates or products of high added value represent an important part of the total production cost. Low liquid to solid ratios and mild temperatures in the pre-treatment are interesting ways of reducing energy costs, subsequently economizing both steam and electricity. This work focuses on the advantages of using low liquid to solid ratios in the hydrothermal treatment of different agro- and forest-industrial wastes, paying particular attention to the performance of separation, purification, and conversion of hemicelluloses.
- Reviewpp 6885-6901Komesu, A., Wolf Maciel, M. R., and Maciel Filho, R. (2017). "Separation and purification technologies for lactic acid – A brief review," BioRes. 12(3), 6885-6901.AbstractArticlePDF
Lactic acid is an important platform chemical with a wide range of applications. Production of lactic acid by fermentation is advantageous because renewable and low cost raw materials can be used as substrates. After fermentation, the broth needs to be purified to obtain pure lactic acid for further uses. Thus, efficient downstream processes are very important because they account for 50% of the production costs. This review discusses different processes that are currently employed for lactic acid recovery, focusing on precipitation, solvent extraction, and separation with membranes. Advances in such recovery processes and drawbacks that limit the application of these technologies at the industrial level are also presented.
- Reviewpp 6868-6884Radics, R. I., Gonzalez, R., Bilek, E. M., and Kelley, S. S. (2017). "Systematic review of torrefied wood economics," BioRes. 12(3), 6868-6884.AbstractArticlePDF
This literature review aims to provide a systematic analysis of studies on the financial aspects of producing torrefied biomass and torrefied pellets. There are substantial differences in the specific technologies, operating conditions, scale of the demonstration, and properties of biomass feedstock. There is a lack of reports that consider the entire supply chain, which is required for an understanding of the high-cost steps. To obtain a robust view of the torrefaction processes’ financial prospects the authors have used both peer-reviewed and non-peer-reviewed papers that allowed the researchers to include thirty-one papers in this analysis. All these studies establish that the prices of the biomass and the final torrefied product are critical. The product yield and caloric content, which are related to pricing, were also key financial drivers. The lower freight costs due to high-energy density of the torrefied pellets was recognized and calculated, but some other benefits were not quantified. There is a need for a detailed and flexible torrefaction financial model that includes variations in financial assumptions and biomass properties. Given the uncertainty around many specific steps, there is value in including stochastic tools in these financial analyses.
- Reviewpp 6844-6867Chin, K., Ibrahim, S., Hakeem, K., H’ng, P., Lee, S., and Mohd Lila, M. (2017). “Bioenergy production from bamboo: Potential source from Malaysia’s perspective,” BioRes. 12(3), 6844-6867.AbstractArticlePDFGlobal energy sectors are facing the crucial challenge of sustainability and diversification of energy resources. Seeking renewable resources with a sustainable supply is therefore a matter of the utmost concern. In this respect, bamboo, a renewable lignocellulosic material and non-food biomass, has great potential to be utilized to produce energy. Several studies have been conducted on a wide range of bamboo species and the results have shown that bamboo could potentially be used as a suitable fuel because it shares desirable fuel characteristics present in other woody biomass. Bamboo can be used as an energy source by converting it into solid, liquid, and gaseous fuels. However, to utilize bamboo as a high promise energy crop resource for biofuels, a secure and stable supply is required. Therefore, additional information on the availability, cultivation, and harvesting operations of bamboo is vital to ensure the practicability of the idea. The objective of this review is to highlight the potential of bamboo as an alternative source of bioenergy production, particularly in a Malaysian context, with emphasis on the concepts, pretreatment, and conversion technologies.
- Reviewpp 4478-4489Mantanis, G. I. (2017). "Chemical modification of wood by acetylation or furfurylation: A review of the present scaled-up technologies," BioRes. 12(2), 4478-4489.AbstractArticlePDF
Significant developments in the area of wood modification have been achieved during the last three decades. These developments can be attributed to increased environmental concerns, the escalating demand for a high and constant quality of wood products, and the rising prices of the durable tropical timber as well as its very limited availability, as affected by illegal logging. As a consequence, a number of wood modification techniques such as chemical and impregnation modifications or heat treatments have been introduced, and some of these technologies have reached the industrial level. This review paper deals with two successful technologies, that is, wood acetylation and wood furfurylation. It briefly discusses the advantages of the new modified products and presents in short their improved properties. Published findings indicate that chemical modification of wood, to a full or partial degree, by means of acetylation or furfurylation, offers a way to transform low durability wood species to new ‘green’ wood materials having advanced qualities and properties.
- Reviewpp 4410-4477Hubbe, M. A., Smith, R. D., Zou, X., Katuscak, S., Potthast, A., and Ahn, K. (2017). "Deacidification of acidic books and paper by means of non-aqueous dispersions of alkaline particles: A review focusing on completeness of the reaction," BioRes. 12(2), 4410-4477.AbstractArticlePDF
Deacidification refers to chemical treatments meant to slow down the acid hydrolysis and embrittlement of books and paper documents that had been printed on acidic paper. From the early 1800s up to about 1990, papermakers used aluminum sulfate, an acidic compound, in most printing papers. Certain deacidification methods use non-aqueous media to distribute alkaline mineral particles such as MgO within the pages of the treated books. Evidence is considered here as to whether or not the proximity of alkaline particles within such documents is sufficient to neutralize the acidic species present. Because much evidence suggests incomplete neutralization, a second focus concerns what to do next in cases where books already have been treated with a non-aqueous dispersion system. Based on the literature, the neutralization of acidic species within such paper can be completed by partial moistening, by high humidity and pressure, by water condensation, as well as by optional treatments to enhance paper strength and a final drying step.
- Reviewpp 4384-4409Bailón-Salas, A. M., Medrano-Roldán, H., Valle-Cervantes, S., Ordaz-Díaz, L. A., Urtiz-Estrada, N., and Rojas-Contreras, J. A. (2017). "Review of molecular techniques for the identification of bacterial communities in biological effluent treatment facilities at pulp and paper mills," BioRes. 12(2), 4384-4409.AbstractArticlePDFOne of the processes most used in biotechnology today for handling industrial liquid wastes is biological wastewater treatment. The efficiency and quality of its operation depends on the composition and activity of the microbial community that is present. The application of traditional and molecular techniques has provided a glimpse into the “black box” and has given information to improve the wastewater treatment process. However, bleach pulp and paper mill effluents require a better understanding of the active bacterial population. For the study of these microorganisms, molecular techniques have been used for more than 15 years. However, there has been a lack of knowledge of the physiological requirements and relations with the environment, which seems to be very difficult to obtain involving profile on the diversity. Nowadays, high-throughput sequencing technology is a promising method that makes it possible to identify the entire profile of microbial communities. In combination with fingerprint methods, this approach allows the identification and analysis of the whole biodiversity of microbial communities. In this review, several identification techniques will be discussed.
- Reviewpp 4364-4383Komesu, A., Oliveira, J. A. R. d., Martins, L. H. d. S., Wolf Maciel, M. R., and Maciel Filho, R. (2017). "Lactic acid production to purification: A review," BioRes. 12(2). 4364-4383.AbstractArticlePDF
Lactic acid is a naturally occurring organic acid that can be used in a wide variety of industries, such as the cosmetic, pharmaceutical, chemical, food, and, most recently, the medical industries. It can be made by the fermentation of sugars obtained from renewable resources, which means that it is an eco-friendly product that has attracted a lot of attention in recent years. In 2010, the U.S. Department of Energy issued a report that listed lactic acid as a potential building block for the future. Bearing the importance of lactic acid in mind, this review summarizes information about lactic acid properties and applications, as well as its production and purification processes.
- Reviewpp 10756-10782Mukhtar, I., Leman, Z., Ishak, M. R., and Zainudin, E. S. (2016). "Sugar palm fibre and its composites: A review of recent developments," BioRes. 11(4), 10756-10782.AbstractArticlePDFThe use of natural fibres as reinforcement in composite materials has increased over the years due to the rapid demand for renewable, cost-effective, and eco-friendly materials in many applications. The most common and adopted natural fibres used as reinforcements are flax, kenaf, hemp, jute, coir, sisal, and abaca. However, sugar palm fibre (SPF) as one of the natural fibres is gaining acceptance as a reinforcement in composites, though it has been known for decades in the rural communities for its multipurpose traditional uses. Sugar palm fibre (SPF) is extracted from sugar palm tree typically from its four morphological parts, namely, trunk, bunch, frond, and the surface of the trunk, which is known as Ijuk. In this paper, sugar palm tree, its fibre and composites, and biopolymers derived from its starch are discussed. Major challenges and the way forward for the use of sugar palm fibre and its composites are highlighted. This review also opens areas for further research on sugar palm fibre and its composites for academia and industries.
- Reviewpp 10711-10755Veettil, S. I., Kumar, L., and Koukoulas, A. A. (2016). "Can microbially derived advanced biofuels ever compete with conventional bioethanol? A critical review," BioRes. 11(4), 10711-10755.AbstractArticlePDF
Microbially derived alkanes and their derivatives are recognized as promising alternatives to petroleum-based fuels and chemicals. We review recent developments in their production, assess progress, and their potential against conventional bioethanol fermentation pathways. The success rate of genetic engineering efforts and their commercialization prospects are assessed, as well as challenges for producing fuels and chemicals from lignocellulosic biomass. Although significant progress has been made in the genetic engineering of microbes used in the production of long-chain hydrocarbons and their derivatives, titer and yield of these biomolecules are currently too low to compete with petroleum-derived products. As for microbially derived isoprenoids or fatty acids, the inherent complexity of micro-organism development will continue to present formidable challenges, making it highly unlikely of any short-term commercial take off. Nonetheless, first generation bioethanol (starch/sugar based) production is commercially established and therefore continued advancements in chemical synthesis should enable broad-scale use of bio-ethanol as a chemical feedstock for the production of advanced biofuels including butanol and other long-chain hydrocarbons.
- Reviewpp 10677-10710Johnson, M. A., and Hart, P. W. (2016). "Integrating a biorefinery into an operating kraft mill," BioRes. 11(4), 10677-10710.AbstractArticlePDF
Kraft pulp and paper mills have several advantages for serving the emerging biorefinery industry as a source of raw materials. This review examines technologies for producing liquid biofuels, chemicals, and advanced materials from woody feedstocks to generate new sources of revenue. Market pull comes in part from government policies that drive substitution of petroleum-based products with biobased equivalents. Kraft mills have ample networks to supply feedstocks, whether these are forest residues or byproduct side streams. Pulp mills are well suited to expand sufficiently to accommodate production of value added platform chemicals that are in demand because of brand owner sustainability commitments.
- Reviewpp 10654-10676Md Shah, A. U., Sultan, M. T. H., Jawaid, M., Cardona, F., and Abu Talib, A. R. (2016). "A review on the tensile properties of bamboo fiber reinforced polymer composites," BioRes. 11(4), 10654-10676.AbstractArticlePDF
This paper reviews the tensile properties of bamboo fiber reinforced polymer composites (BFRP). Environmentally friendly bamboo fibers have good mechanical properties, which make them suitable replacements for conventional fibers, such as glass and carbon, in composite materials. Better fiber and matrix interaction results in good interfacial adhesion between fiber/matrix and fewer voids in the composite. Several important factors improve matrix-fiber bonding and enhance the tensile properties of BFRP. Coupling agents, such as maleic anhydride polypropylene (MAPP), improve the adhesion of bamboo fibers in the polypropylene (PP) matrix. A high percentage of lignin content in bamboo fibers limits fiber separation, which leads to less matrix absorption between fibers. Steam explosion is the best extraction method for bamboo fibers, although an additional mechanically rubbing process is required for fiber separation. Generally, high fiber content results in good composite performance, but at a certain limit, the matrix does not adhere well with a saturated amount of fibers, and the composite tensile strength decreases. However, the tensile modulus of BFRP is not affected by excess fiber content. Hybridization of bamboo with conventional fibers increases the tensile strength of BFRP. The addition of micro/nano-sized bamboo fibrils into the carbon fabric composites slightly enhances composite strength.
- Reviewpp 10625-10653Sarip, H., Sohrab Hossain, M., Azemi M. N., M., and Allaf, K. (2016). "A review of the thermal pretreatment of lignocellulosic biomass towards glucose production: Autohydrolysis with DIC technology," BioRes. 11(4), 10625-10653.AbstractArticlePDFThere is increasing demand for the production of biofuels from lignocellulosic biomass. Lignocellulosic biomass consists mainly of three polymeric components: cellulose, hemicelluloses, and lignin. The separation of these components requires an effective pretreatment process to ensure high quality glucose production, and is highly influenced by several factors, including moisture content, cellulose crystallinity, lignin content, and available surface area. Over time, numerous pretreatment methods have been utilized to change the lignocellulosic fiber structure and to enhance the enzymatic saccharification of cellulose to polysaccharides. This article reviews thermal-based pretreatment of lignocellulosic fiber used for glucose production. Based on the reviewed studies, autohydrolysis of lignocellusic biomass, followed by the “Instant pressure drop (DIC),” method can be regarded as an effective pretreatment process of lignocellusic biomass.
- Reviewpp 10604-10624Kaur, P. J., Satya, S., Pant, K. K., and Naik, S. N. (2016). "Eco-friendly preservation of bamboo species: Traditional to modern techniques," BioRes. 11(4), 10604-10624.AbstractArticlePDFThe continuous depletion of forests calls for the astute usage of existing resources. Fungi and termites cause serious damage to biomass under storage and service conditions. Various protective treatments with high amounts of toxic chemicals are used by the wood and bamboo industry. Efforts are being made the world over to develop environmentally friendly preservatives for wood and bamboo species. Recent research highlights the potential and effectiveness of traditional practices and procedures, mainly water leaching technique and smoke treatment. Under laboratory conditions, the service life of treated blocks were found to be at a par with commercial chemical preservative treated blocks. Various plant extracts and oil-based formulations, such as organic acids, essential oils, and eco-friendly chemical-based preservatives, are in the stage of development. The bio-efficacy of such preservatives is measured in terms of the improvement in resistance to fungi and termites. However, much work still needs to be done to completely determine the efficacy of many of these newly developed preservatives and techniques. The present paper discusses an overview of the developments in the field of environment-friendly biomass preservatives.
- Reviewpp 10585-10603Jin, J., Chen, S., and Wellwood, R. (2016). "Oriented strand board: Opportunities and potential products in China," BioRes. 11(4), 10585-10603.AbstractArticlePDFNorth America’s first oriented strand board (OSB) mill was built in the early 1980’s. Twenty years later, the industry was thriving, with over 50 mills producing the product. China’s first OSB mill was built in 1990, and 25 years later, there are a few mills with a total capacity less than two large North America mills, most operating below capacity and struggling to identify domestic markets for the growing production. This paper briefly looks at the histories of OSB industries in North America and China, presents the current situation of China’s wood-based panels industry and its downstream industries, and identifies OSB opportunities and potential products in China. Opportunity for sheathing-grade OSB is very limited in the current Chinese market, whereas industrial opportunities for specialty OSB products to replace plywood have great potential. Those specialty products include materials for furniture, wood doors, wood flooring, container flooring, concrete form, etc. OSB producers must designate the right OSB products for the Chinese market and cost-effectively manufacture those differentiated products to meet specifications for various end-applications.
- Reviewpp 8092-8115Pan, M., Zhu, L., Chen, L., Qiu, Y., and Wang, J. (2016). "Detection techniques for extracellular polymeric substances in biofilms: A review" BioRes. 11(3), 8092-8115.AbstractArticlePDF
Extracellular polymeric substances (EPS) are one of the main components of biofilm, prompting biofilm to form a cohesive three-dimensional framework. Numerous methods are available to help characterize the properties and the structural, chemical and physical organizations of EPS during the biofilm formation process. This review highlights key techniques from different disciplines that have been successfully applied in-situ and non-destructively to describe the complex composition and distribution of EPS in biofilm, especially microscopic, spectroscopic, and the combination of multi-disciplinary methods that can provide new insights into the complex structure/function correlations in biofilms. Among them, confocal laser scanning microscopy (CLSM) is emphasized, and its principles, applications, advantages, and limitations are summarized. Multidisciplinary techniques have been developed and recommended to study EPS during the biofilm formation process, providing more in-depth insights into the composition and spatial distributions of EPS, so as to improve our understanding of the role EPS plays in biofilms ultimately.
- Reviewpp 7953-8091Hubbe, M. A., Metts, J. R., Hermosilla, D., Blanco, M. A., Yerushalmi, L., Haghighat, F., Lindholm-Lehto, P., Khodaparast, Z., Kamali, M., and Elliott, A. (2016). "Wastewater treatment and reclamation: A review of pulp and paper industry practices and opportunities," BioRes. 11(3), 7953-8091.AbstractArticlePDF
The pulp and paper (P&P) industry worldwide has achieved substantial progress in treating both process water and wastewater, thus limiting the discharge of pollutants to receiving waters. This review covers a variety of wastewater treatment methods, which provide P&P companies with cost-effective ways to limit the release of biological or chemical oxygen demand, toxicity, solids, color, and other indicators of pollutant load. Conventional wastewater treatment systems, often comprising primary clarification followed by activated sludge processes, have been widely implemented in the P&P industry. Higher levels of pollutant removal can be achieved by supplementary treatments, which can include anaerobic biological stages, advanced oxidation processes, bioreactors, and membrane filtration technologies. Improvements in the performance of wastewater treatment operations often can be achieved by effective measurement technologies and by strategic addition of agents including coagulants, flocculants, filter aids, and optimized fungal or bacterial cultures. In addition, P&P mills can implement upstream process changes, including dissolved-air-flotation (DAF) systems, filtration save-alls, and kidney-like operations to purify process waters, thus reducing the load of pollutants and the volume of effluent being discharged to end-of-pipe wastewater treatment plants.
- Reviewpp 7928-7952Singh, D., Cubbage, F., Gonzalez, R., and Abt, R. (2016). "Locational determinants for wood pellet plants: A review and case study of North and South America," BioRes. 11(3), 7928-7952.AbstractArticlePDF
The European Union’s Renewable Energy Directive has led many electricity producers in Europe to use wood pellets in place of fossil fuels. North America has become one of the primary suppliers of wood pellets to Europe. This paper critically examines literature, economic models and data, as well as the supply chain and country risk factors, related to wood pellet production to anticipate where North and South American pellet mills should be built to meet Europe’s demand. Canada, the United States, and Brazil maintain the largest natural forest area, planted forest area, and industrial roundwood production; however, South American countries achieve faster plantation growth rates. The World Bank’s Logistic Procurement Index and IHS’s Country Risk Index were used to score and rank countries’ investment climates, based on their supply chain and risk factors. In this regard, the United States, Canada, and Chile performed best, in contrast to Venezuela, Bolivia, and Ecuador. When considering both wood supply and investment climates, the United States, Canada, and Chile were the most attractive countries to build a pellet mill, while countries, such as Argentina, Brazil, Colombia, Paraguay, and Peru present significant trade-offs between having significant wood resources and riskier investment climates.
- Reviewpp 7917-7927Wu, C. (2016). "The potential of pre-hydrolysis liquor from the dissolving pulp process as recovery source of xylooligosaccharide - A mini-review," BioRes. 11(3), 7917-7927.AbstractArticlePDF
Currently, xylooligosaccharides (XOs), which are a kind of nutraceutical that can be produced from lignocellulosic biomass, have an important place in the global market. In this critical review the raw materials and manufacturing methods of XOs are briefly considered. The results in some publications indicate that the pre-hydrolysis liquor (PHL) from dissolving pulp process is a potential source of XOs. However, it is very difficult to separate and further remove the lignin in PHL, which is detrimental to the separation and further purification of XOs. Based on these problems, a number of important aspects with respect to PHL, including industrial treatment technologies, composition, and lignin removal technologies, are described in this review. In addition, some XOs purification technologies in PHL are also introduced.
- Reviewpp 7902-7916Liu, Y., Shi, L., Cheng, D., and He, Z. (2016). "Dissolving pulp market and technologies: Chinese prospective - A mini-review," BioRes. 11(3), 7902-7916.AbstractArticlePDF
Cellulose is the most abundant natural polymer on earth. As the market and the public demands more and more natural products, cellulose and its derivatives are becoming increasingly more attractive. The production of dissolving pulp, which is the main feedstock for cellulose-related products, has been growing over the past decade, while the technologies for manufacturing these pulps have also been advanced. In this literature review, the production and consumption of dissolving pulp are analyzed with a focus on the Chinese market. The manufacturing processes, including raw materials, pulping methods, pulp bleaching, and post-treatments are discussed.
- Reviewpp 7889-7901De Araujo, V. A., Cortez-Barbosa, J., Gava, M., Garcia, J. N., Souza, A. J., Savi, A. F., Morales, E. A. M., Molina, J. C., Vasconcelos, J. S., Christoforo, A. L., and Lahr , F. A. R. (2016)."Classification of wooden housing building systems," BioRes. 11(3), 7889-7901.AbstractArticlePDF
Wooden housing is one of the most sustainable building alternatives. In many European and North American countries, wooden houses provide the most common, economical, and practical solution for construction. The timber buildings present adequate levels of durability, acoustics, and thermal comforts. Despite their popularity, wood houses do not have a standardized classification to define and organize their main aspects. In literature dealing with timber construction, most authors emphasize structural systems for large spans (bridges, hangars, roofs, etc.). The presence of some classifications of timber construction results in unclear issues, and few studies have covered and regarded wooden buildings as residential construction typologies. Accordingly, this paper proposes a classification that connects the aspects and details of wooden housing materials in relation to the industrialization level and chronological origin. We expect this classification to assist in a better understanding of distinct wooden housing techniques commercially produced worldwide, diffusing their concepts and possibilities as forestry-timber products.
- Reviewpp 7859-7888Pásztory, Z., Mohácsiné, I. R., Gorbacheva, G., and Börcsök, Z. (2016). "The utilization of tree bark," BioRes. 11(3), 7859-7888.AbstractArticlePDF
The utilization of natural raw materials has been practiced for centuries. Of raw materials, wood and its bark have outstanding significance because of their special chemical components and unusual structure. Annual bark production is estimated to be between 300 and 400 million m3. The bark of different tree species has been used extensively in or in conjunction with modern technologies. This article presents a comprehensive summary of these methods of utilization and their results. The diversity of bark utilization derives from the variety of the bark of different species and from the possibilities encoded in the material. Following the anatomic summary, the protective role of the bark is discussed, highlighting its physical-chemical properties and the different methods of medical, energetic, and industrial utilization.
- Reviewpp 5641-5655Arévalo Gallegos, A. M., Carrera, S. H., Parra, R., Keshavarz, T., and Iqbal, H. M. N. (2016). "Bacterial cellulose: A sustainable source to develop value-added products - A review," BioRes. 11(2), 5641-5655.AbstractArticlePDF
In recent decades, worldwide economic and environmental issues have prompted research scientists to re-direct their interests to bio-based resources, which are sustainable in nature. In this context, microbial polysaccharides, such as bacterial cellulose (BC), also known as microbial cellulose (MC), are some of the upcoming and emergent resources and have potential application in various bio- and non-bio-based sectors of the modern world. Many researchers have already established novel BC/MC production methods, and many new studies have been published on lab-scale and large-scale production aspects of BC/MC to date. To further expand the novel use of this sustainable source, significant progress toward the development of BC/MC has appeared in recent years. Specifically, there have been many publications and/or research reports on the valorization of BC/MC in the food, paper, materials, biomedical, pharmaceutical, and cosmeceutical industries, among others. This review will address the novel application aspects of BC/MC today, with the aim of demonstrating the importance of this sustainable and novel source in the development of value-added products.
- Reviewpp 5618-5640Villaverde, J. J., Sandín-España, P., Sevilla-Morán, B., López-Goti, C., and Alonso-Prados, J. L. (2016). "Biopesticides from natural products: Current development, legislative framework, and future trends," BioRes . 11(2), 5618-5640.AbstractArticlePDF
The importance of biomass as a source of chemicals, biofuels, and energy is widely accepted. Currently, the attention is mainly focused on the valorisation of by-products from lignocellulosic materials. Chemical compounds derived from plants and microorganisms that provide good protection for crops against weeds, pests, and diseases (biopesticide active substances) have been used to formulate pesticides. Their use is increasingly encouraged by new pesticide regulations that discourage the use of harmful active substances. This article reviews the current and future situation of biopesticides, especially natural chemical products, and focuses on their potential within the European pesticide legislative framework. Moreover, this article highlights the importance of the different modes/mechanisms of action of the active substances obtained from natural sources, the role of chemistry in biopesticide development, and how the adoption of integrated pest management practices contributes to a greater trend towards biopesticides.
- Reviewpp 5600-5617Tajuddin, M., Ahmad, Z., and Ismail, H. (2016). "A review of natural fibers and processing operations for the production of binderless boards," BioRes. 11(2), 5600-5617.AbstractArticlePDF
Decreasing wood supplies and the need for formaldehyde-free particleboard have become important issues. This has led to studies about the use of raw materials other than wood, along with the manufacture of particleboard without using any synthetic adhesives. This paper presents an overview of the development of binderless boards from natural fibers using a diverse range of manufacturing processes, such as heat and steam treatments. The features of binderless boards produced with various parameters, such as pressing parameters, particle sizes, and additional substances, under various manufacturing processes, are discussed. Based on the availability of natural fibers, binderless boards are typically evaluated for their physical, mechanical, and thermal properties. This review is approached with an understanding of the processes and contributing factors in producing binderless boards, helping to overcome some critical issues that are necessary for the development of future new “green” binderless boards through value-addition to enhance their usage.
- Reviewpp 5581-5599Mou, H. L., Wu, S., and Fardim, P. (2016). "Applications of ToF-SIMS in surface chemistry analysis of lignocellulosic biomass: A review," BioRes. 11(2), 5581-5599.AbstractArticlePDF
Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) is an advanced surface-sensitive technique that can provide both spectral and imaging information about materials. Recently, ToF-SIMS has been used for advanced studies of lignocellulosic biomass. In the current article, the application of ToF-SIMS to the characterization of the surface chemical composition and distribution of biomass components in lignocelluloses is reviewed. Moreover, extended applications of ToF-SIMS in the study of pretreatments, modification of biomaterials, and enzyme activity of lignocellulosic materials are presented and discussed. Sample preparation prior to ToF-SIMS analysis and subsequent interpretation of results is a critical factor in ensuring reliable results. The focus of this review is to give a comprehensive understanding of and offer new hints about the effects of processing conditions on the surface chemistry of lignocellulosic biomass.
- Reviewpp 5553-5564Chen, C., Duan, C., Li, J., Liu, Y., Ma, X., Zheng, L., Stavik, J., and Ni, Y. (2016). "Cellulose (dissolving pulp) manufacturing processes and properties: A mini-review," BioRes.11(2), 5553-5564.AbstractArticlePDF
The increasing consumption of regenerated cellulose, in particular the viscose fiber, has led to a significant development of dissolving pulps in the last decade. In this review paper, the current status of dissolving pulp with respects to raw materials, manufacturing processes, and some key issues are discussed. Non-wood materials and the process concept of upgrading paper-grade pulp into dissolving pulp are also included. Some recent developments related to the analytical methods of the purity and molecular weight distribution based on the ion chromatography and gel permeation chromatography are discussed. Finally, further processing improvements of purification, such as mechanical, chemical, and enzymatic treatment, and their combinations during the manufacturing process of dissolving pulp, are included.
- Reviewpp 5565-5580Rosli, F., Ghazali, C. M. R., Abdullah, M. M. A. B., and Hussin, K. (2016). "A review: Characteristics of oil palm trunk (OPT) and quality improvement of palm trunk plywood by resin impregnation," BioRes . 11(2), 5565-5580.AbstractArticlePDF
Due to the shortage of solid wood as a raw material of plywood and the abundance of oil palm trunk (OPT) waste in Malaysia, OPT has become one of the potential replacements for timber. However, OPT plywood has low performance compared with commercial plywood, due to the poor properties of OPT. There are many recent studies related to quality improvement using thermosetting impregnation, especially with formaldehyde-based resins such as urea formaldehyde (UF) and phenol formaldehyde (PF). Nevertheless, there are very limited studies related to palm trunk plywood using thermoplastic impregnation and formaldehyde-free adhesive. Formaldehyde effects can be avoided by replacing it with a thermoplastic adhesive, such as acrylonitrile butadiene styrene (ABS), to enhance and improve the quality of the plywood manufactured from OPT. In Malaysia, palm trunk plywood is used currently for non-structural materials such as formworks, cabinets, and packaging material. Hence, the enhanced quality of palm trunk plywood with a formaldehyde-free thermoplastic adhesive could produce a higher quality palm trunk plywood.
- Reviewpp 5482-5499Matsakas, L., Rova, U., and Christakopoulos, P. " Strategies for enhanced biogas generation through anaerobic digestion of forest material - An overview," BioRes.11(2), 5482-5499.AbstractArticlePDF
Incorporation of biofuels into the existing selection of fuels is a very important measure to slow down environmental destruction and to counter the imminent fossil fuel shortage. Biogas is a very interesting option for use in both electricity and heat production, and also as a fuel for vehicles. The positive fuel characteristics of biogas and the high yields of biogas obtained from traditional raw materials (e.g., animal manure) have resulted in operation of several commercial units around the globe. On the other hand, there is an increased demand for biogas production which, for the need to be met, should have renewable resources incorporated into it. Forest materials are an interesting candidate, and there is a rising interest in the research and industrial communities to exploit them as raw materials for anaerobic digestion in biogas production. In this review article, we aim to give the reader an insight into the most recent processes for conversion of various sources of forest materials into biogas.
- Reviewpp 5500-5552Hubbe, M. A., and Koukoulas, A. A. (2016). "Wet-laid nonwovens manufacture - Chemical approaches using synthetic and cellulosic fibers," BioRes. 11(2), 5500-5552.AbstractArticlePDF
Wet-laid forming, which can be regarded as being analogous to conventional papermaking processes but with use of chopped synthetic or staple fibers, continues to draw attention as an advantageous way to prepare advanced nonwoven textile products. This review of the literature considers scientific advances in the field, with emphasis placed on applications involving cellulosic fibers as a significant component of the product. Some primary challenges with respect to wet-laid processing concern the dispersion of the synthetic fibers in aqueous media and methods for avoiding their subsequent entanglement. Both mechanical and chemical strategies have been employed in order to achieve well-formed sheets of high uniformity and binding among the fibers to meet a variety of end-use specifications. The incorporation of cellulosic fibers has been shown to facilitate fiber dispersion and to impart certain beneficial characteristics and properties to wet-laid fabrics. The contrasting attributes of synthetic and cellulosic fibers contribute to some unique challenges during the processing of their mixtures during wet-laid forming.
- Reviewpp 5452-5481Espinoza-Acosta, J. L., Torres-Chávez, P. I., Ramírez-Wong, B., López-Saiz, C. M., and Montaño-Leyva, B. "Antioxidant, antimicrobial, and antimutagenic properties of technical lignins and their applications," BioRes. 11(2), 5452-5481.AbstractArticlePDF
At present, more than 70 million tons per year of technical lignins are obtained from cellulose pulping and lignocellulosic refineries (e.g., kraft, lignosulfonates, soda, and organosolv lignin). These lignins are commonly incinerated to produce steam and energy, and only a small part is used as an additive in various low volume and niche applications, such as dispersant, in concrete admixtures, as an adhesive and as a binder. Furthermore, the potential of technical lignins is considered to be beyond that of an inexpensive fuel or raw material to produce low added value products. The technical lignins consist of complex polyphenolic polymers that contain numerous chemical functional groups, such as phenolic hydroxyl, carboxylic, carbonyl, and methoxyl groups. The phenolic hydroxyl and methoxyl groups present in lignin reportedly possess various biological activities. The amount of data describing the biological activities of technical lignins has increased in the last 10 years. This review presents the most relevant research concerning the various biological activities (antioxidant, antimicrobial, antimutagenic, and others) of technical lignins. Additionally, the most promising and relevant applications are highlighted.
- Reviewpp 2886-2963Hubbe, M. A., and Gill, R. A. (2016). "Fillers for papermaking: A review of their properties, usage practices, and their mechanistic role," BioRes. 11(1), 2886-2963.AbstractArticlePDF
Issues of cost and product quality have caused papermakers to place increased attention on the use of mineral additives, which are the subject of this review article. Technologists responsible for the production of paper can choose from a broad range of natural and synthetic mineral products, each of which has different characteristic shapes, size distributions, and surface chemical behavior. This article considers methods of characterization, and then discusses the distinguishing features of widely available filler products. The mechanisms by which fillers affect different paper properties is reviewed, as well as procedures for handling fillers in the paper mill and retaining them in the paper. Optical properties of paper and strategies to maintain paper strength at higher filler levels are considered. The goal of this review is to provide background both for engineers working to make their paper products more competitive and for researchers aiming to achieve effects beyond the current state of the art.
- Reviewpp 2850-2885Tang, Y., Rosenberg, J. N., Bohutskyi, P., Yu, G., Betenbaugh, M. J., and Wang, F. (2016). "Microalgae as a feedstock for biofuel precursors and value-added products: Green fuels and golden opportunities," BioRes. 11(1), 2850-2885.AbstractArticlePDF
The prospects of biofuel production from microalgal carbohydrates and lipids coupled with greenhouse gas mitigation due to photosynthetic assimilation of CO2 have ushered in a renewed interest in algal feedstock. Furthermore, microalgae (including cyanobacteria) have become established as commercial sources of value-added biochemicals such as polyunsaturated fatty acids and carotenoid pigments used as antioxidants in nutritional supplements and cosmetics. This article presents a comprehensive synopsis of the metabolic basis for accumulating lipids as well as applicable methods of lipid and cellulose bioconversion and final applications of these natural or refined products from microalgal biomass. For lipids, one-step in situ transesterification offers a new and more accurate approach to quantify oil content. As a complement to microalgal oil fractions, the utilization of cellulosic biomass from microalgae to produce bioethanol by fermentation, biogas by anaerobic digestion, and bio-oil by hydrothermal liquefaction are discussed. Collectively, a compendium of information spanning green renewable fuels and value-added nutritional compounds is provided.
- Reviewpp 8812-8858Eseyin, A. E., Steele, P. H., and Pittman Jr., C. U. (2015). "Current trends in the production and applications of torrefied wood/biomass - A review," BioRes. 10(4), 8812-8858.AbstractArticlePDF
Trends in the production and applications of torrefied wood/biomass are reviewed in this article. The thermochemical conversion of biomass is a promising technology because biomass is an environmentally friendly fuel that produces substantially lower CO2 emissions compared to fossil fuel. Torrefaction is the thermal treatment of biomass at temperatures from 200 to 300 ˚C in the absence of air or oxygen to liberate water and release volatile organic compounds, primarily through the decomposition of the hemicelluloses. Torrefied biomass has a higher heating value, is more hydrophobic, resists rotting, and has a prolonged storage time. The different torrefaction technologies and reactors are described. An overview of the applications of torrefied biomass, the economic status, and future prospects of torrefaction technology are presented and discussed. Currently, torrefaction demonstration plants have technical problems that have delayed their commercial operation. Torrefaction reactors still require optimization to economically meet end-use requirements and attain product standardization for the market. Several characteristics of torrefaction need to be demonstrated or scaled up for successful commercialization.
- Reviewpp 8795-8811Kerekes, R. J. (2015). "Perspectives on high and low consistency refining in mechanical pulp," BioRes. 10(4), 8795-8811.AbstractArticlePDF
Recent developments in low consistency refining in mechanical pulping have raised questions about the differences between low and high consistency refining. This paper, originally presented to the UBC Energy Reduction in Mechanical Pulping Committee on 10 June 2015 at the PACWEST Conference in Whistler, BC, Canada, discusses the author’s perspectives on these issues as well as on mechanical pulping in general.
- Reviewpp 8770-8794Radics, R., Dasmohapatra, S., and Kelley, S. S. (2015). "Systematic review of bioenergy perception studies," BioRes. 10(4), 8770-8794.AbstractArticlePDF
This paper presents the results of a structured review of published articles that discuss stakeholders’ perceptions of bioenergy, including both biofuels and biopower. An electronic search process using numerous key terms identified 44 peer-reviewed publications from 2000 to 2013 that focused on stakeholders’ perceptions, understanding, and acceptance of bioenergy. These findings indicate that in the last decade the research community has been more active in publications focused on the societal and public perceptions of the bioenergy industry compared to prior years. Among the reviewed studies, most (84%) are based in the US and Europe, and only a few recent studies have focused on stakeholders in Asia and other parts of the world. This review revealed no standardized methods for evaluation of stakeholder perception, for data collection, or statistical analysis of the data. Among stakeholder groups, the majority of studies focused on the general public or the consumer’s opinion about bioenergy (79% of studies). Overall findings show that the stakeholder groups show low to moderate support for the bioenergy industry. As anticipated, the stakeholder groups had varied views about the opportunities and risks associated with bioenergy industry, and these views varied based on their experiences.
- Reviewpp 8750-8769Zhang, A., Shen, J., and Ni, Y. (2015). "Anaerobic digestion for use in the pulp and paper industry and other sectors: An introductory mini review," BioRes. 10(4), 8750-8769.AbstractArticlePDF
Anaerobic digestion is a well-established biological process for converting biomass in waste streams into a renewable energy source, and it also contributes to the treatment of these waste streams. In this introductory mini-review, some fundamental aspects of anaerobic digestion for use in the pulp and paper industry and other sectors are briefly summarized. The contents include the basics of anaerobic digestion, feedstocks, key process parameters, and typical anaerobic digesters/reactors and their representative manufactures. Fostering the more efficient and widespread commercial use of anaerobic digestion technologies would be a critical strategy to address the issues of energy, the environment, and sustainability.
- Reviewpp 8604-8656Lehto, J. T., and Alén, R. J. (2015). "Chemical pretreatments of wood chips prior to alkaline pulping - A review of pretreatment alternatives, chemical aspects of the resulting liquors, and pulping outcomes," BioRes. 10(4),8604-8656.AbstractArticlePDF
The chemical industry is being forced to evaluate new strategies for more effective utilization of renewable feedstocks to diminish the use of fossil resources. In this literature review, the integration of both acidic and alkaline pretreatment phases of hardwood and softwood chips with chemical pulping is discussed. Depending on the pretreatment conditions, high-volume sulfur-free fractions with varying chemical compositions can be produced. In case of acidic pretreatments, the major products include carbohydrates (mono-, oligo-, and polysaccharides), whereas under alkaline (i.e., aqueous NaOH) pretreatment conditions, the sulfur-free fractions of aliphatic carboxylic acids, lignin, and extractives are primarily obtained. All these fractions are potentially interesting groups of compounds and can be used in a number of applications. Finally, the effects of pretreatments on pulping are also considered. Although it is believed that there are important advantages to be gained by integrating this type of renewable raw material-based production, in particular, with kraft pulping, sulfur-free pulping methods such as soda-AQ and oxygen/alkali delignification processes are also briefly discussed.
- Reviewpp 8657-8749Hubbe, M. A., Gardner, D. J., and Shen, W. (2015). "Contact angles and wettability of cellulosic surfaces: A review of proposed mechanisms and test strategies," BioRes. 10(4), 8657-8749.AbstractArticlePDF
Contact angle methods are widely used to evaluate the wettability of cellulose-based surfaces and to judge their suitability for different applications. Wettability affects ink receptivity, coating, absorbency, adhesion, and frictional properties. There has been a continuing quest on the part of researchers to quantify the thermodynamic work of adhesion between cellulosic surfaces and various probe liquids and to account for such components of force as the London/van der Waals dispersion force, hydrogen bonding, and acid and base interactions. However, due in part to the rough, porous, and water-swellable nature of cellulosic materials, poor fits between various theories and contact angle data have been observed. Such problems are compounded by inherent weaknesses and challenges of the theoretical approaches that have been employed up to this point. It appears that insufficient consideration has been given to the challenging nature of cellulosic materials from the perspective of attempting to gain accurate information about different contributions to surface free energy. Strong hysteresis effects, with large differences between advancing and receding contact angles, have been overlooked by many researchers in attempting to quantify the work of adhesion. Experimental and conceptual approaches are suggested as potential ways to achieve more reliable and useful results in future wettability studies of cellulosic surfaces.
- Reviewpp 8580-8603Salman, S. D., Leman, Z., Sultan, M. T. H., Ishak, M. R., and Cardona, F. (2015). "Kenaf/synthetic and Kevlar®/ cellulosic fiber-reinforced hybrid composites: A review," BioRes. 10(4), 8580-8603.AbstractArticlePDF
This paper reviews the published and ongoing research work on kenaf/synthetic and Kevlar®/cellulosic fiber-reinforced composite materials. The combination of natural fibers with synthetic fibers in hybrid composites has become increasingly applied in several different fields of technology and engineering. As a result, a better balance between performance and cost is expected to be achieved by 2015, through appropriate material design. This review is intended to provide an outline of the essential outcomes of those hybrid composite materials currently utilized, focusing on processing and mechanical and structural properties.
- Reviewpp 6262-6284Nasir, M., Hashim, R., Sulaiman, O., Nordin, N. A., Lamaming, J., and Asim, M. (2015). "Laccase, an emerging tool to fabricate green composites: A review," BioRes. 10(3), 6262-6284.AbstractArticlePDF
In the last two decades, laccases have received much attention from researchers because of their specific ability to oxidize lignin. This function of laccase is very useful for applications in several biotechnological processes, including delignification in the pulp and paper industry and the detoxification of industrial effluents from the textile and petrochemical industries. This review focuses on laccase-mediated fiberboard synthesis. Growing concerns regarding the emission of formaldehyde from wood composites has prompted industrialists to consider the fabrication of green composites. Laccase-mediated fiber treatments oxidize the lignin component without affecting the cellulose structure. As a result, free radicals are generated on the fiber surface, and these can act as potential reactive sites for further cross-linking reactions in board manufacturing. Binderless fiberboards prepared using such methods can be considered as green composites because the manufacturing process involves no additional resin.
- Reviewpp 6285-6304Xu, J., Li, M., and Ni, T. (2015). "Feedstock for bioethanol production from a technological paradigm perspective," BioRes. 10(3), 6285-6304.AbstractArticlePDF
Because of the impending energy crisis and the environmental problems caused by the excessive use of fossil fuels, biofuels produced from renewable energy biomass have been playing a more significant role in the world. This follows from their obvious environmental and economic advantages. Bioethanol, the most widely used transportation biofuel, is typically derived from plant-based feedstock sources such wheat, sugar beet, corn, straw, and wood. However, the main problem with bioethanol production is that despite the range of feedstock, raw material availability varies considerably from season to season, as there is no systematic framework. By combining technological paradigm theory with literature mining, we found that bioethanol feedstock production development has followed a three-stage trajectory, which is in accordance with the traditional technological paradigm – the S-curve. This new curve can be divided into BFDP (bioethanol feedstock development paradigm) competition, BFDP diffusion, and BFDP shift. Each phase has a different generation of feedstock; first-generation bioethanol in BFDP competition, second-generation bioethanol in BFDP diffusion, and third-generation bioethanol in BFDP shift. Further, based on the technological support, literature mining, and a realistic background, the second-generation bioethanol (mainly lignocellulosic biomass) is expected to continue to be a significant future trend in the world. The new BFDP framework presented in this paper may provide scholars with research ideas for the future.
- Reviewpp 6230-6261Reza, M., Kontturi, E., Jääskeläinen, A. S., Vuorinen, T., and Ruokolainen, J. (2015). "Transmission electron microscopy for wood and fiber analysis - A Review," BioRes. 10(3), 6230-6261.AbstractArticlePDF
This review describes use of transmission electron microscopy (TEM) in wood and fiber analysis. Analytical techniques and sample preparation methods are used to localize substructures of the cell wall polymers and are discussed in this review. The ultrastructural features of the wood cell walls, the structures formed by microfibrils, and the distribution of cell wall polymers, as revealed by TEM, are covered. Research investigating the distribution of lignin in tension and compression woods using TEM is reviewed. Different kinds of wood biodegrading enzymes localized using TEM are mentioned. Additional features of TEM, i.e., 3D imaging, analytical TEM, and electron diffraction are discussed. Lastly, a comparison between TEM and other imaging techniques used for wood and fiber research are made. Thus, this review provides insight into the contribution of TEM in wood research since its invention and demonstrates how to use it more effectively in the future.
- Reviewpp 6207-6229Pereira, H. (2015). "The rationale behind cork properties: A review of structure and chemistry," BioRes. 10(3), 6207-6229.AbstractArticlePDF
Cork is a natural cellular material of biological origin with a combination of properties that make it suited for worldwide use as a wine sealant and insulation material. Cork has low density, is buoyant, is not very permeable to fluids, has a low thermal coefficient, exhibits elasticity and deformation without fracturing under compression, and has considerable durability. Such characteristics result from the features of its cellular structure, primarily its cell dimensions and topology, and from the chemical composition of the cell wall. The characteristics of the two main chemical components (suberin and lignin, which represent 53% and 26%, respectively, of the cell wall) have been analyzed. The limits of natural variation and their impacts on cork properties are discussed and used to define the material as “cork”.
- Reviewpp 6095-6206Hubbe, M. A., Rojas, O. J., and Lucia, L. A. (2015). "Green modification of surface characteristics of cellulosic materials at the molecular or nano scale: A review," BioRes. 10(3), 6095-6206.AbstractArticlePDF
Many current and potential uses of cellulosic materials depend critically on the character of their surfaces. This review of the scientific literature considers both well-established and emerging strategies to change the outermost surfaces of cellulosic fibers or films not only in terms of chemical composition, but also in terms of outcomes such as wettability, friction, and adhesion. A key goal of surface modification has been to improve the performance of cellulosic fibers in the manufacture of composites through chemistries such as esterification that are enabled by the high density of hydroxyl groups at typical cellulosic surfaces. A wide variety of grafting methods, some developed recently, can be used with plant-derived fibers. The costs and environmental consequences of such treatments must be carefully weighed against the potential to achieve similar performances by approaches that use more sustainable methods and materials and involve less energy and processing steps. There is potential to change the practical performances of many cellulosic materials by heating, by enzymatic treatments, by use of surface-active agents, or by adsorption of polyelectrolytes. The lignin, hemicelluloses, and extractives naturally present in plant-based materials also can be expected to play critical roles in emerging strategies to modify the surfaces characteristics of cellulosic fibers with a minimum of adverse environmental impacts.
- Reviewpp 6081-6094Yang, F., Jin, E. S., Zhu, Y., Wu, S., Zhu, W., Jin, Y., and Song, J. (2015). "A Mini-review on the applications of cellulose-binding domains in lignocellulosic material utilizations," BioRes. 10(3), 6081-6094AbstractArticlePDF
This manuscript provides a mini review on the fundamentals of cellulose binding domains (CBDs) or cellulose binding modules (CBMs) and their applications using lignocellulosic materials. CBDs, the non-productive part of cellulases, have miscellaneous biological functions and have been widely applied in lignocellulose hydrolysis, protein engineering, structural support, metabolism, energy storage, antibiosis, immunological recognition, targeting, attachment, etc. due to their specific affinity to various substrates of lignocelluloses. Understanding of the properties and mechanisms of CBDs is of vital significance because it provides the basis for fine manipulation of cellulose-CBM interactions and eventually improves the bioconversion performance of lignocelluloses into fuels and desired chemicals. In this short review, the fundamentals of CBD, the definition of CBM family, and the structures of different CBM families are introduced. Then recent findings in the applications of CBDs are discussed relative to the lignocelllulosic utilizations.
- Reviewpp 6055-6080Gómez-de la Cruz, F. J., Casanova-Peláez, P. J., López-García, R., and Cruz-Peragón, F. (2015). "Review of the drying kinetics of olive oil mill wastes: Biomass recovery," BioRes. 10(3), 6055-6080.AbstractArticlePDF
The drying kinetics of olive oil mill wastes was analyzed based on experiments carried out by various researchers utilizing different drying systems. A critical review of the literature was done, and mathematical models of drying curves proposed by investigators were evaluated. A comparison between the best mathematical models of fit in the drying curves used in past experiments and a two-term Gaussian model was performed. This model improved all the results of fit in each experiment. Drying rates and drying stages were obtained and discussed. An average drying rate for each experiment from the two-term Gaussian model was calculated. This value allowed for visualizing and comparing the average speed of evaporated water in each experiment for the different dryers. Finally, and after having verified that almost all drying occurs mainly by a diffusion phenomenon, an analysis on the effective moisture diffusivity and activation energy values was performed. The results indicated that there was no dependency of these quantities on independent variables such as the drying air temperature, the drying air velocity, and the sample thickness. It follows that drying of olive oil mill wastes is a very complex physical process that depends heavily on aspects such as pieces of pit, pulp, skin, vegetation water, olive oil content, sugars and organics compounds of different nature.
- Reviewpp 1964-1985Liu, Y., Ren, X., and Liang, J. (2015). "Antibacterial modification of cellulosic materials," BioRes. 10(1), 1964-1985.AbstractArticlePDF
The proliferation of bacteria on the surfaces of cellulosic materials during their use and storage can have negative effects on the materials themselves and on consumers. People’s demands for materials with antibacterial properties have been satisfied in recent years because of the emergence of various antibacterial compounds. This paper reviews recent research and development progress in antibacterial modification of cellulosic fibers using various biocides such as N-halamines, quaternary ammonium salts, chitosan, triclosan, and nanoparticles composed of noble metals and metal oxides. Antibacterial mechanisms and treating methods for antibacterial cellulosic materials are also involved in this paper.
- Reviewpp 1915-1963Pintiaux, T., Viet, D., Vandenbossche, V., Rigal, L., and Rouilly, A. (2015). "Binderless materials obtained by thermo-compressive processing of lignocellulosic fibers: A comprehensive review," BioRes. 10(1), 1915-1963.AbstractArticlePDF
As the worldwide demand for fuels and materials increases, fossil resources are decreasing and global warming is a concern, and thus the need for alternative solutions is high. In the industries of furniture and housing, particleboards are interesting materials, as they reutilize wastes from other industries (wood, agriculture) although they also rely on chemical binders that are petroleum-based and toxic. A very promising alternative is then clearly identified in finding ways to produce binderless boards and associated materials. This review considers the state of the art in the field of binderless board production, and other processes making it possible to turn raw plant fibers into structural materials without using any external chemistry. The mechanical properties and water resistance are collected and compared. Identified chemistry changes occurring during the thermo-compressive process are discussed with an aim towards understanding of the mechanisms of cohesion.
- Reviewpp 1879-1914Ioelovich, M. (2015). "Recent findings and the energetic potential of plant biomass as a renewable source of biofuels - A review," BioRes. 10(1), 1879-1914.AbstractArticlePDF
Nowadays the main sources of energy are petroleum, coal, and natural gas. However, these fossil sources are not reproduced in nature; on a human timescale their reserves are exhausted permanently and run down. Considerable attention in recent years has been given to plant biomass, which in contrast to the fossil sources is continuously renewed in nature. In this critical review the use of non-edible plant biomass for production of various kinds of biofuels is considered. To generate energy, plant biomass either can be burned directly or it can be used after its conversion into carbonized solid fuel (e.g. biochar), liquid fuels (bioethanol, biodiesel, bio-oil), or gases (biogas). Among various biofuels, production of bioethanol has potential to be the most attractive if recent technological advances become implemented, such that the co-production of ethanol and valuable byproducts can be combined together with recycling of solid and liquid wastes. A comparative analysis of energetic potential of biomass and various kinds of biofuels revealed that the most efficient way to produce energy is by direct burning of the plant biomass in a pelletized form, while the burning of such amount of the solid, liquid, or gaseous biofuel, which can be obtained from the plant material, gives a much smaller energetic effect. Novel types of pellets, as well as solid/liquid biofuels, having improved fuel characteristics are described.
- Reviewpp 7951-8001Vishtal, A., and Retulainen, E. (2014). "Boosting the extensibility potential of fibre networks: A review," BioRes. 9(4), 7951-8001.AbstractArticlePDF
Production of paper-based packaging is growing at the present moment and has great future prospects. However, the development of new packaging concepts is creating a demand for an improvement in the mechanical properties of paper. Extensibility is one of these properties. Highly extensible papers have the potential to replace certain kinds of plastics used in packaging. Extensibility is also important for the sack and bag paper grades and for runnability in any converting process. This paper reviews the factors that affect the extensibility of fibres and paper, and discusses opportunities for improving the straining potential of paper and paper-like fibre networks. It is possible to classify factors that affect extensibility into three main categories: fibre structure, interfibre bonding, and structure of the fibre network. Extensibility is also affected by the straining situation and the phase state of the polymers in the cell wall. By understanding the basic phenomena related to the elongation, and by combining different methods affecting the deformability of fibre network, extensibility of paper can be raised to a higher level.
- Reviewpp 7941-7950Sarmin, S. N., Welling, J., Krause, A., and Shalbafan, A. (2014). "Investigating the possibility of geopolymer to produce inorganic-bonded wood composites for multifunctional construction material - A Review," BioRes. 9(4), 7941-7950.AbstractArticlePDF
Wood-based composites are widely used in consumer products, either in structural or non-structural applications. One of the basic elements for wood-based composites is the binder itself. Recent years have seen great development and trends in the field of eco-friendly binders in wood-based composite. There have been many concerns on the effects of formaldehyde and volatile organic compounds (VOC) released from wood-based products. Researchers have put lot of effort into developing environmental friendly products with enhanced sustainability. Binder materials with a focus on geopolymers (i.e., alumino-silicates) are discussed in this publication. The development and utilization of geopolymeric binders is relatively new in the field of wood-based composites. Up to the present there has been insufficient information regarding the manufacturing conditions and properties of wood-nonwood composite materials prepared using a geopolymeric binder. This paper considers the background of geopolymer materials and the possibilities of producing inorganic-bonded wood composite using geopolymer.
- Reviewpp 7782-7925Hubbe, M. A., Park, J., and Park, S. (2014). "Cellulosic substrates for removal of pollutants from aqueous systems: A review. Part 4. Dissolved petrochemical compounds," BioRes. 9(4), 7782-7925.AbstractArticlePDF
Dissolved petroleum-based compounds, e.g. solvents, pesticides, and chemical reagents such as phenolic compounds, can pose significant hazards to the health of humans and ecosystems when they are released to the environment. This review article considers research progress related to the biosorption and removal of such contaminants from water using cellulose-derived materials. The fact that cellulosic materials show promise in removing such sparingly soluble materials from water lends support to a hypothesis that lignocellulosic materials can be broad-spectrum adsorbents. Also, the hydrophobic character and sorption capabilities can be increased through thermal treatment and the preparation of activated carbons. As shown in many studies, the efficiency of uptake of various petrochemical products from water also can be increased by chemical treatments of the adsorbent. It appears that more widespread adoption of biosorption as a means of removing petroleum-based products from water has been limited by concerns about the used, loaded biosorbent. Disposal or regeneration options that need to be considered more in future research include enzymatic and biological treatments, taking advantage of the fact that the biosorbent material is able to collect, immobilize, and concentrate various contaminants in forms that are suited for a number of packed bed or batch-type degradative treatment systems.
- Reviewpp 7926-7940Ooi, Z. X., Ismail, H., Abu Bakar, A., and Teoh, Y. P. (2014). "A review on recycling ash derived from Elaeis guineensis by-product," BioRes. 9(4), 7926-7940.AbstractArticlePDF
Oil palm (Elaeis guineensis) ash is defined as the waste generated after the combustion of oil palm biomass. Malaysia is one of the world’s largest producers and exporter of palm oil in the world, and there is approximately 4 million tonnes of oil palm ash generated annually. It is estimated that the amount of oil palm ash will keep increasing due to the high demand for palm oil globally. Normally, oil palm ash is disposed without any beneficial economic return value. The awareness of this environmental crisis has increased significantly over the past few years. With the evolution of ash utilization strategies, interest in oil palm ash in various research fields has grown. Through the effort of researchers and information available, the properties of the resulting materials are affected by the percentage of substitution and particle size of the oil palm ash. The major challenges in utilizing oil palm ash are discussed in this paper, as are the beneficial effects, which can include reducing the negative environmental impact and the product cost. Although the recycling of oil palm ash is still a new focus of interest, the main thrust of waste management in Malaysia will continue to focus on this kind of research and will attempt to solve the problem of disposal of the ash as well.
- Reviewpp 5738-5773Knob, A., Fortkamp, D., Prolo, T., Izidoro, S. C., and Almeida, J. M. (2014). "Agro-residues as alternative for xylanase production by filamentous fungi," BioRes. 9(3), 5738-5773.AbstractArticlePDF
Agro-industrial wastes are the most abundant renewable resource on earth and are available in large quantities. However, the disposal of these wastes presents an increasing environmental problem. Recently, there has been a great interest in the exploitation of these wastes as low-cost raw materials for the production of value-added compounds as microbial enzymes by submerged or solid-state fermentation systems. This review focuses on alternatives for xylanase production using agro-residues as substrates. In recent years, the interest in xylanase, which plays an important role in the breakdown of xylan, has markedly increased due to its wide variety of biotechnological applications. Among several agro-industrial residues that have been intensively investigated, many, such as wheat bran, wheat straw, and sugarcane bagasse, are suitable and result in high yields of xylanase, leading to low production costs. In addition, many relatively unexplored residues, such as oil palm wastes, sorghum straw, and coffee by-products, are some of the most promising substrates for xylanase production, requiring further assessment.
- Reviewpp 5707-5737Akinbomi, J., Brandberg, T., Sanni, S. A., and Taherzadeh, M. J. (2014). "Development and dissemination strategies for accelerating biogas production in Nigeria," BioRes. 9(3), 5707-5737.AbstractArticlePDF
Following the worsening energy crisis of unreliable electricity and unaffordable petroleum products coupled with the increase number of poverty-stricken people in Nigeria, the populace is desperately in need of cheap alternative energy supplies that will replace or complement the existing energy sources. Previous efforts by the government in tackling the challenge by citizenship sensitization of the need for introduction of biofuel into the country’s energy mix have not yielded the expected results because of a lack of sustained government effort. In light of the shortcomings, this study assesses the current potential of available biomass feedstock for biogas production in Nigeria, and further proposes appropriate biogas plants, depending on feedstock type and quantity, for the six geopolitical zones in Nigeria. Besides, the study proposes government-driven biogas development systems that could be effectively used to harness, using biogas technology, the estimated 270 TWh of potential electrical energy from 181 million tonnes of available biomass, in the advancement of electricity generation and consequent improvement of welfare in Nigeria.
- Reviewpp 5688-5706Namvar, F., Jawaid, M., Md Tahir, P., Mohamad, R., Azizi, S., Khodavandi, A., Rahman, H. S., and Nayeri, M. D. (2014). "Potential use of plant fibres and their composites for biomedical applications," BioRes. 9(3), 5688-5706.AbstractArticlePDF
Plant-based fibers such as flax, jute, sisal, hemp, and kenaf have been frequently used in the manufacturing of biocomposites. Natural fibres possess a high strength to weight ratio, non-corrosive nature, high fracture toughness, renewability, and sustainability, which give them unique advantages over other materials. The development of biocomposites by reinforcing natural fibres has attracted attention of scientists and researchers due to environmental benefits and improved mechanical performance. Manufacturing of biocomposites from renewable sources is a challenging task, involving metals, polymers, and ceramics. Biocomposites are already utilized in biomedical applications such as drug/gene delivery, tissue engineering, orthopedics, and cosmetic orthodontics. The first essential requirement of materials to be used as biomaterial is its acceptability by the human body. A biomaterial should obtain some important common properties in order to be applied in the human body either for use alone or in combination. Biocomposites have potential to replace or serve as a framework allowing the regeneration of traumatized or degenerated tissues or organs, thus improving the patients’ quality of life. This review paper addresses the utilization of plant fibres and its composites in biomedical applications and considers potential future research directed at environment-friendly biodegradable composites for biomedical applications.
- Reviewpp 3733-3754Gangwar, A. K., Prakash, N. T., and Prakash, R. (2014). "Applicability of microbial xylanases in paper pulp bleaching: A review," BioRes. 9(2), 3733-3754.AbstractArticlePDF
The pulp and paper industries are attempting to bring changes to the bleaching process to minimize the use of chlorine to satisfy regulatory and market demands. Xylanases offer a cost-effective way for mills to realize a variety of benefits in bleaching. One main benefit is reducing Adsorbable Organic Halides (AOX) discharge. This is achieved primarily by decreasing chlorine gas usage. Other benefits include eliminating chlorine gas usage in mills with high chlorine dioxide substitution levels and increasing the brightness ceiling (particularly for mills contemplating Elemental Chlorine Free (ECF) and Totally Chlorine Free (TCF) bleaching sequences and in mills using large amounts of peroxide or chlorine dioxide). These benefits are achieved in the long term when the enzymes are properly selected and integrated into the process. This review summarizes the application of xylanases in the bleaching of pulp, with emphasis on the mechanism and effects of xylanase treatment on pulp and paper and the factors affecting the bleaching process and its efficiency. Brightness gains of up to 1.4 to 2.1 units have been achieved with xylanase treatment with the reduction of chlorine consumption by 15.0%. Xylanase treatment can lower the AOX amount in filtrate by 25.0% as compared to references. The Chemical Oxygen Demand (COD) can be reduced by 85%.
- Reviewpp 3688-3732Lindholm, P. C., Knuutinen, J. S., Ahkola, H. S. J., and Herve, S. H. (2014). "Analysis of trace pharmaceuticals and related compounds in municipal wastewaters by preconcentration, chromatography, derivatization, and separation methods," BioRes. 9(2), 3688-3732.AbstractArticlePDF
A significant portion of pharmaceuticals and other organic chemicals consumed by people and animals are released into municipal wastewater treatment plants. Most of them are degraded during the wastewater treatment processes, but some of them degrade only partially and may be widely transported and dispersed into the aquatic environment. This is why efficient and fast analytical methods are needed for detection of organic compounds in wastewaters at trace levels. Because wastewaters often consist of complex matrices and high-molecular mass materials, e.g., lignocellulosic biomass, which may bring challenges to the sample preparation procedures, efficient pre-concentration methods such as solid phase extraction (SPE) solid phase microextraction (SPME), or single‑drop microextraction (SDME) are needed. The most common analysis methods are gas chromatography (GC) and liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS). The aim of this review is to give an overview of chromatographic and spectroscopic methods when characterizing low- and medium-molecular weight organic pollutants, mainly focusing on pharmaceuticals, biocides, and personal care products in environmental matrices.
- Reviewpp 3660-3687Espinoza-Acosta, J. L., Torres-Chávez, P. I., Carvajal-Millán, E., Ramírez-Wong, B., Bello-Pérez, L. A., and Montaño-Leyva, B. (2014). "Ionic liquids and organic solvents for recovering lignin from lignocellulosic biomass," BioRes. 9(2), 3660-3687.AbstractArticlePDF
Lignin contributes to the recalcitrance of lignocellulosic biomass and affects enzymatic activity during biorefinery operations. Therefore, it must be removed before further processing. Organic solvents (organosolv) and ionic liquids are two important pretreatments for delignifying lignocellulosic biomass. They have proven beneficial for fractionating and recovering cellulose and hemicellulose, as well as lignin with useful physicochemical properties. Volatility and harsh conditions of the acidic systems that result in toxicity, corrosion, and pollution are the main problems of organosolv. Ionic liquids, generally recognized as green solvents, have also been proposed as a possible solution to the challenge of using lignocellulosic biomass. Ionic liquids can either dissolve the lignocellulosic biomass completely or dissolve it into individual fractions. This review considers the advantages and disadvantages of organosolv and ionic liquids, since both are important methods to fractionate lignocellulosic biomass in their main components which can be converted into value added products.
- Reviewpp 3642-3659Khan, B. A., Warner, P., and Wang, H. (2014). "Antibacterial properties of hemp and other natural fibre plants: A review," BioRes. 9(2), 3642-3659.AbstractArticlePDF
Intervention against pathogenic bacteria using natural plant material has a long history. Plant materials also have been widely used as fillers and/or reinforcers in polymer composites. Some natural fibre plants, such as hemp, are regarded to possess antibacterial activity against a wide range of pathogenic bacteria. Innovative applications can be explored if they are incorporated in polymer composites. This review aims to compile the relevant investigations on antibacterial activity of hemp and other fibre plants such as jute, flax, kenaf, sisal, and bamboo. The antibacterial character might be contributed from cannabinoids, alkaloids, other bioactive compounds, or phenolic compounds of lignin. This review is intended to encourage utilization of hemp and other natural fibre plants in value-added diversified products. Some potential applications are also discussed.
- Reviewpp 1787-1823Chowdhury, Z. Z., Mohd. Zain, S., Abd Hamid, S. B., and Khalid, K. (2014). "Catalytic role of ionic liquids for dissolution and degradation of biomacromolecules," BioRes. 9(1), 1787-1823.AbstractArticlePDF
Natural biomacromolecules constitute a diverse feedstock, including carbohydrate-based polysaccharides (cellulose, hemicellulose, starch, agarose, and Konjac glucomannan) together with lignin — extracted mainly from biomass — and other protein based polymers, namely keratin, chitin, chitosan, and silk fibroin. The complex and heterogeneous chemical structure of biomacromolecules makes them difficult to dissolve and disintegrate into simpler molecules for further applications. In this regard, ionic liquids are potential solvents for the dissolution and modification of long chain biopolymers. This provides a promising pretreatment technology and is known to allow adequate extraction of biopolymers from natural sources. This paper highlights the properties of ionic liquids for their use as versatile solvents. This review provides a critical outlook regarding the influence of several process parameters that govern the fractionation of biomacromolecules into their constituent elements and further pretreatment processes. The performance of different types of ionic liquids for processing of biomacromolecules, focusing on their pertinent capability as catalysts to enhance the rate of hydrolysis, also is discussed in this article.
- Reviewpp 1634-1763Hubbe, M. A. (2014). "Prospects for maintaining strength of paper and paperboard products while using less forest resources: A Review,"BioRes. 9(1), 1634-1763.AbstractArticlePDF
Paper production requires large amounts of cellulosic fiber, whereas the world’s forested lands and croplands have a finite capacity to supply such resources. To deal with likely future pressure on forest resources, as well as to hold down costs of materials, publications examined in the preparation of this review suggest that the paper industry will need to implement several concurrent strategies. In particular, the industry can be expected to view recycling as a central part of its activities. Basis weights of various paper-based products can be expected to decrease over the coming decades, and more of the fiber content will be replaced with fillers such as calcium carbonate. Such trends will place intense demands upon chemical-based strategies to enhance the bonding within paper and paperboard. Based on the literature, further progress in reducing the amount of new forest resources used to meet a given set of paper product requirements will require a combined approach, taking into account various fiber attributes, nanostructures, novel concepts in bond formation, and advances in the unit operations of papermaking.
- Reviewpp 1764-1786Zhu, X., Kim, B.-J., Wang, Q., and Wu, Q. (2014). "Recent advances in the sound insulation properties of bio-based materials," BioRes. 9(1), 1764-1786.AbstractArticlePDF
Many bio-based materials, which have lower environmental impact than traditional synthetic materials, show good sound absorbing and sound insulation performances. This review highlights progress in sound transmission properties of bio-based materials and provides a comprehensive account of various multiporous bio-based materials and multilayered structures used in sound absorption and insulation products. Furthermore, principal models of sound transmission are discussed in order to aid in an understanding of sound transmission properties of bio-based materials. In addition, the review presents discussions on the composite structure optimization and future research in using co-extruded wood plastic composite for sound insulation control. This review contributes to the body of knowledge on the sound transmission properties of bio-based materials, provides a better understanding of the models of some multiporous bio-based materials and multilayered structures, and contributes to the wider adoption of bio-based materials as sound absorbers.
- Reviewpp 1606-1633Rajkumar, R., Yaakob, Z., and Takriff, M. S. (2014). "Potential of the micro and macro algae for biofuel production: A brief review," BioRes. 9(1), 1606-1633.AbstractArticlePDF
The world seems to be raising its energy needs owing to an expanding population and people’s desire for higher living standards. Diversification biofuel sources have become an important energy issue in recent times. Among the various resources, algal biomass has received much attention in the recent years due to its relatively high growth rate, its vast potential to reduce greenhouse gas (GHG) emissions and climate change, and their ability to store high amounts of lipids and carbohydrates. These versatile organisms can also be used for the production of biofuel. In this review, sustainability and the viability of algae as an up-coming biofuel feedstock have been discussed. Additionally, this review offers an overview of the status of biofuel production through algal biomass and progress made so far in this area.
- Reviewpp 6630-6649Rodrigues, J. N., Dias, A. M. P. G., and Providência, P. (2013). "Timber-concrete composite bridges: State-of-the-art review," BioRes. 8(4), 6630-6649.AbstractArticlePDF
This review article presents a state-of-the-art survey on timber-concrete composite (TCC) bridges. It starts with a presentation of a sample of relevant TCC bridges, offering a global perspective on the use of this type of bridge. The number of TCC bridges has clearly increased in the past few years, and some of the reasons for this trend are explored. Next, an extensive literature review is presented regarding the most significant technological innovations and recent developments in the application of TCC structures to bridge construction. Firstly, the engineering specificities and the advantages of TCC bridge structural systems are enumerated. Afterwards, the importance of proper mechanical connection for optimal performance of TCC structures is explained, and a thorough description of the connection systems suitable for bridge construction is provided. Some research into the structural behavior of TCC bridges under service conditions is then presented and discussed. Finally, possible areas of future research regarding the development of TCC bridges are suggested.
- Reviewpp 6523-6555Chowdhury, Z. Z., Abd Hamid, S. B., Das, R., Hasan, M. R., Zain, S. M., Khalid, K., and Uddin, M. N. (2013). "Preparation of carbonaceous adsorbents from lignocellulosic biomass and their use in removal of contaminants from aqueous solution," BioRes. 8(4), 6523-6555.AbstractArticlePDF
The feasibility of using lignocellulosic biomass as a source for preparing carbon adsorbents has received rigorous attention over the last few decades. Many studies have discussed its great potential as a renewable feedstock for preparation of carbonaceous adsorbent materials. This review paper provides an overview of the different types of carbonization techniques that so far have been applied to convert lignocellulosic biomass to carbon adsorbents. The effects of various process parameters on the conventional pyrolysis process are reviewed. The paper focuses on the mechanism for the formation of carbons, its wide variety of applications for waste effluents, and the regeneration techniques so far adopted by researchers. Low-cost carbons derived from lignocellulosic biomass have demonstrated excellent capabilities for the removal of organic and inorganic contaminants, including some pharmaceutical compounds, from the waste aqueous stream.
- Reviewpp 6556-6629Hubbe, M. A., Ayoub, A., Daystar, J. S., Venditti, R. A., and Pawlak, J. J. (2013). "Enhanced absorbent products incorporating cellulose and its derivatives: A Review," BioRes. 8(4), 6556-6629.AbstractArticlePDF
Cellulose and some cellulose derivatives can play vital roles in the enhancement of the performance of absorbent products. Cellulose itself, in the form of cellulosic fibers or nano-fibers, can provide structure, bulk, water-holding capacity, and channeling of fluids over a wide dimensional range. Likewise, cellulose derivatives such as carboxymethylcellulose (CMC) have been widely studied as components in superabsorbent polymer (SAP) formulations. The present review focuses on strategies and mechanisms in which inclusion of cellulose – in its various forms – can enhance either the capacity or the rate of aqueous fluid absorption in various potential applications.
- Reviewpp 4775-4790Salem, M. Z. M., and Böhm, M. (2013). "Understanding of formaldehyde emissions from solid wood: An overview," BioRes. 8(3), 4775-4790.AbstractArticlePDF
Wood is known to contain and emit volatile organic compounds including formaldehyde. The emission of formaldehyde from wood increases during its processing to lumber and wood-based panels (i.e., particleboard and fiberboard). This increased emission can be attributed to the processing procedure of wood, which includes drying, pressing, and thermo-hydrolysis. Formaldehyde is emitted from wood under very high heat and is not expected to be a significant source of the emissions from composite wood products during normal service. Formaldehyde is also detectable even if wood has never been heated as well as under more or less ambient conditions. The presence of formaldehyde in the emissions from wood that does not contain adhesive resin has been explained by thermal degradation of polysaccharides in the wood. The emission levels of formaldehyde depend on factors such as wood species, moisture content, outside temperature, and time of storage. Additionally, the pyrolysis of milled wood lignin at 450 °C yields benzaldehyde, and the pyrolysis of spruce and pinewood at 450 °C generate formaldehyde, acetaldehyde, 2–propenal, butanal, and butanone, which can be attributed to the breakdown of the polysaccharide fraction of the wood.
- Reviewpp 3157-3176Iqbal, H. M. N., Kyazze, G., and Keshavarz, T. (2013). "Advances in the valorization of lignocellulosic materials by biotechnology: An overview," BioRes. 8(2), 3157-3176.AbstractArticlePDF
In view of the worldwide economic and environmental issues associated with the extensive use of petro-chemicals, there has been increasing research interest during the past decade in the value of residual biomass. Because of its renewable nature and abundant availability, residual biomass has attracted considerable attention as an alternate feedstock and potential energy source. To expand the range of natural bio-resources, significant progress related to the lignocellulose bio-technology has been achieved, and researchers have been re-directing their interests to biomass-based fuels, ligninolytic enzymes, chemicals, and biocompatible materials, which can be obtained from a variety of lignocellulosic waste materials. This review article focuses on the potential applications of lignocellulosic materials in biotechnology, including the production of bio-fuels, enzymes, chemicals, the pulp and paper, animal feed, and composites.
- Reviewpp 3136-3156Dungani, R., Jawaid, M., Abdul Khalil, H. P. S., Jasni, Aprilia, S., Hakeem, K. R., Hartati, S., and Islam, M. N. (2013). "A review on quality enhancement of oil palm trunk waste by resin impregnation: Future materials," BioRes. 8(2), 3136-3156.AbstractArticlePDF
Oil palm trunk (OPT) is a solid waste obtained in large quantities after the felling of oil palm trees and is available year-round. Scientists and industrialists face difficulties in utilizing these solid wastes for different applications due to great variations in their physical and mechanical properties. Because OPT consists of lignocellulosic materials, its cellulosic material is utilized in the production of panel products such as particleboard, medium density fibreboard, mineral-bonded particleboard, block board, and cement board. In order to control the OPT waste, it is essential to consider its alternative utilization inside buildings as lightweight construction materials and furniture. The impregnation of different resins in wood and non-wood materials can improve the quality of the OPT, making it possible to utilize OPT as raw materials for different applications. The enhanced properties and good appearance of impregnated OPT have found use in high-grade furniture and housing materials. In order to further evaluate its potential, this review has been compiled for the detailed study of various properties, characteristics, and applications of OPT.
- Reviewpp 3122-3135Naylor, A., and Hackney, P. (2013). "A review of wood machining literature with a special focus on sawing," BioRes. 8(2), 3122-3135.AbstractArticlePDF
In this review, fundamental wood machining research is evaluated to determine the general cutting mechanics of simple, orthogonal, and oblique cutting tools. Simple tool force trends and chip formation characteristics are indentified here, along with the cause and effects of tool wear. In addition to this, specific methods of evaluating sawing processes have been investigated. These include the use of piezoelectric dynamometers to record tool forces and high speed photography to evaluate chip formation. Furthermore, regression analysis has been previously used to identify tool force trends with respect to both tooth geometry parameters and work-piece properties. This review has identified the original findings of previous research. This will allow for further original research to be conducted.
- Reviewpp 3038-3097Hubbe, M. A., Rojas, O. J., Fingas, M., and Gupta, B. S. (2013). "Cellulosic substrates for removal of pollutants from aqueous systems: A Review. 3. Spilled oil and emulsified organic liquids," BioRes. 8(2), 3038-3097.AbstractArticlePDF
Water-insoluble oils, including crude petroleum and a wide variety of refined organic liquids, can cause major problems if spilled or leaked to aqueous environments. Potential environmental damage may be reduced if the spilled oil is promptly and efficiently removed from the water. This article reviews research that sheds light on the use of cellulose-based materials as sorbents to mitigate effects of oil spills. Encouraging results for oil sorption have been reported when using naturally hydrophobic cellulosic fibers such as unprocessed cotton, kapok, or milkweed seed hair. In addition, a wide assortment of cellulosic materials have been shown to be effective sorbents for hydrocarbon oils, especially in the absence of water, and their performance under water-wet conditions can be enhanced by various pretreatments that render them more hydrophobic. More research is needed on environmentally friendly systems to handle oil-contaminated sorbents after their use; promising approaches include their re-use after regeneration, anaerobic digestion, and incineration, among others. Research is also needed to further develop combined response systems in which biosorption is used along with other spill-response measures, including skimming, demulsification, biodegradation, and the use of booms to limit the spreading of oil slicks.
- Reviewpp 3098-3121Paunonen, S. (2013). "Strength and barrier enhancements of cellophane and cellulose derivative films: A Review," BioRes. 8(2), 3098-3121.AbstractArticlePDF
Cellulose derivatives, i.e. cellulose functionalized in a solvent state with various side groups, are an important source of biomaterials for food packaging. This review considers the following materials: i) cellophane, ii) cellulose acetate, iii) methylcellulose, and iv) carboxymethylcellulose. Mechanical and barrier properties are important for freestanding packaging films as well as for coatings. The potential of the selected cellulose derivatives and cellophane is thus examined from the viewpoint of their tensile properties as well as their moisture and oxygen barrier properties. The capacity of microcrystalline cellulose and nano-sized celluloses to reinforce the films and to help impede gas diffusion is examined for microfibrillar celluloses, nanocrystalline celluloses, and whiskers. Very good oxygen barrier properties have been reported for cellophane. Nanocellulose fillers have regularly been shown to enhance the tensile properties of several cellulose derivatives, but the effects on the water vapor permeability (WVP) have been studied less often.
- Reviewpp 1478-1507Teacă, C.-A., Roşu, D., Bodîrlău, R., and Roşu, L. (2013). "Structural changes in wood under artificial UV light irradiation determined by FTIR spectroscopy and color measurements - A brief review," BioRes. 8(1), 1478-1507.AbstractArticlePDF
UV weathering, a process initiated primarily by the ultraviolet portion of the solar spectrum, causes surface degradation of wood. Additionally, the wetting and drying of wood through precipitation, diurnal and seasonal changes in relative humidity, abrasion by air particulates, temperature changes, atmospheric pollution, oxygen, and human activities, all contribute to the degradation of wood surfaces. Photo-oxidation or photo-chemical degradation affects only the wood surface, starting immediately after exposure to sunlight. Understanding the chemistry of UV degradation of wood requires knowledge of the chemical nature of wood components, the UV spectrum, and the interactions of UV radiation with various chemical structures in wood. Chemical changes can be evidenced by FTIR spectroscopy. Previous study has shown that wood chemical modification with succinic anhydride makes it slightly more stable to the artificial light action than non-modified wood, which might be due to a slight increase in lignin stability to the polychromatic light action. Analysis of color changes on coated wood surfaces for modified wood treated with epoxidized soybean oil (ESO) has shown that lightness (ΔL*) decreases, whereas a*, b*, and ΔE* increase with increasing irradiation time.
- Reviewpp 1431-1455Miao, Q., Huang, L., and Chen, L. (2013). "Advances in the control of dissolved and colloidal substances present in papermaking processes: A brief review," BioRes. 8(1), 1431-1455.AbstractArticlePDF
In the production of paper, especially when using mechanical pulp or recovered wood-containing paper, a large amount of dissolved and colloidal substances (DCS), mainly composed of hemicelluloses, extractives, lignans, and lignin-related substances, are released from the pulp and dissolved or dispersed into the process water. The accumulation of DCS during the papermaking operations due to the closure of process water systems gives rise to various detrimental impacts on the papermaking process and the resulting paper products. Thus it is indispensible to remove or control the DCS in order to overcome or alleviate their negative influences. This review emphasizes recent advances in control of DCS by physical, chemical, and biological methods. The widely used fixatives such as aluminum sulfate, poly-(aluminum chloride), polyamines, polyvinyl amine, and highly cationic starch, as well as their functional effectiveness, mechanism, influencing factors, and influences on paper products are considered. Simultaneously, biological treatments including fungal treatment and enzymatic treatments with lipase, pectinase, laccase, and immobilized enzymes, are also assessed in detail. DCS control has been an important way to improve the runnability of paper machines and the quality of wood-containing paper and recycled paper products. Advances in DCS control are likely to create additional benefits to the papermaking industry in the coming years.
- Reviewpp 1456-1477Santos, R. B., Hart, P. W., Jameel, H., and Chang, H.-M. (2013). "Wood based lignin reactions important to the biorefinery and pulp and paper industries," BioRes. 8(1), 1456-1477.AbstractArticlePDF
The cleavage of lignin bonds in a wood matrix is an important step in the processes employed in both the biorefinery and pulp and paper industries. β-O-4 ether linkages are susceptible to both acidic and alkaline hydrolysis. The cleavage of α-ether linkages rapidly occurs under mildly acidic reaction conditions, resulting in lower molecular weight lignin fragments. Acidic reactions are typically employed in the biorefinery industries, while alkaline reactions are more typically employed in the pulp and paper industries, especially in the kraft pulping process. By better understanding lignin reactions and reaction conditions, it may be possible to improve silvicultural and breeding programs to enhance the formation of easily removable lignin, as opposed to more chemically resistant lignin structures. In hardwood species, the S/G ratio has been successfully correlated to the amount of β-O-4 ether linkages present in the lignin and the ease of pulping reactions.
- Reviewpp 6077-6108Pönni, R., Vuorinen, T., and Kontturi, E. (2012). "Proposed nano-scale coalescence of cellulose in chemical pulp fibers during technical treatments," BioRes. 7(4), 6077-6108.AbstractArticlePDF
This review summarizes the proposed mechanisms for irreversible coalescence of cellulose microfibrils within fibers during various common industrial treatments for chemical pulp fibers as well as the methods to evaluate it. It is a phenomenon vital for cellulose accessibility but still under considerable debate. The proposed coalescence mechanisms include irreversible hydrogen bonding. Coalescence is induced by high temperature and by the absence of obstructing molecules, such as water, hemicelluloses, and lignin. The typical industrial processes, in the course of which nano-scale coalescence and possible aggregation of cellulose microfibrillar elements occurs, are drying and chemical pulping. Coalescence reduces cellulose accessibility and therefore, in several instances, the quality of cellulose as a raw material for novel products. The degree of coalescence also affects the processing and the quality of the products. For traditional paper-based products, the loss of strength properties is a major disadvantage. Some properties lost during coalescence can be restored to a certain extent by, e.g., beating. Several factors, such as charge, have an influence on the intensity of the coalescence. The evaluation of the phenomenon is commonly conducted by water retention value measurements. Other techniques, such as deuteration combined with FTIR spectroscopy, are being applied for better understanding of the changes in cellulose accessibility.
- Reviewpp 6109-6193Hubbe, M. A., Sundberg, A., Mocchiutti, P., Ni, Y., and Pelton, R. (2012). "Dissolved and colloidal substances (DCS) and the charge demand of papermaking process waters and suspensions: A Review," BioRes. 7(4), 6109-6193.AbstractArticlePDF
Dissolved and colloidal substances (DCS) in the process waters of paper machine systems can interfere with the retention of fine particles, retard the drainage of water from the wet web, and generally hurt the intended functions of various polyelectrolytes that are added to the process. This review considers publications that have attempted to characterize the nature and effects of different DCS fractions, in addition to some of the ways that paper technologists have attempted to overcome related problems. The consequences of DCS in a paper machine system can be traced to their ability to form complexes with various polyelectrolytes. Such tendencies can be understood based on a relatively strong complexing ability of multivalent materials, depending on the macromolecular size and charge density. Continuing research is needed to more fully understand the different contributions to cationic demand in various paper machine systems and to find more efficient means of dealing with DCS.
- Reviewpp 6041-6076Valto, P., Knuutinen, J., and Alén, R. (2012). "Overview of analytical procedures for fatty and resin acids in the papermaking process," BioRes. 7(4), 6041-6076.AbstractArticlePDF
This review describes the role of wood extractives, especially fatty and resin acids, in papermaking, as well as the importance of their removal from process waters. One of the main aims is also to illustrate versatile analysis methods for this purpose and highlight recent developments in corresponding applications. Most of the current methods require time-consuming and laborious sample pretreatment procedures prior to gas chromatography coupled either with flame ionization or mass selective detection. However, some faster, even online techniques with minimum sample pretreatment, are also available, mainly including high performance liquid chromatography coupled with mass spectrometry. The advantages and disadvantages of all analytical procedures are briefly discussed.
- Reviewpp 5995-6040Paulsson, M., and Parkås, J. (2012). "Review: Light-induced yellowing of lignocellulosic pulps – Mechanisms and preventive methods," BioRes. 7(4), 5995-6040.AbstractArticlePDF
This review will focus on recent progress regarding the mechanisms of light-induced discoloration of mechanical and chemimechanical pulps and on the proposed preventive treatments. It is evident that the mechanisms behind photoyellowing of lignin-rich pulps are complex and that several types of reaction pathways may coexist. Photoyellowing proceeds via one initial fast phase and a slower following phase. The fast phase has been ascribed to oxidation of free phenolic groups and/or hydroquinones and catechols to photoproducts of mainly quinonoid character. A multitude of reactions involving several lignin subunits are possible. Important intermediates are phenoxyl radicals, and to some extent ketyl radicals. The importance of the phenacyl aryl ether pathway might be more important than previously thought, even though the original content of such groups is low in lignin. Even though many preventive methods against photoyellowing have been suggested, no cost-efficient treatment is available to hinder photoreversion of lignin-containing paper permanently. Suggested methods for stabilization include chemical modification (etherification and esterification), coating the paper product, addition of radical scavengers, excited state quenchers, or ultraviolet absorbing compounds.
- Reviewpp 4451-4490Stelte, W., Sanadi, A. R., Shang, L., Holm, J. K., Ahrenfeldt, J., and Henriksen, U. B. (2012). "Recent developments in biomass pelletization - A review," BioRes. 7(3), 4451-4490.AbstractArticlePDF
The depletion of fossil fuels and the need to reduce greenhouse gas emissions has resulted in a strong growth of biomass utilization for heat and power production. Attempts to overcome the poor handling properties of biomass, i.e. its low bulk density and inhomogeneous structure, have resulted in an increasing interest in biomass densification technologies, such as pelletization and briquetting. The global pellet market has developed quickly, and strong growth is expected for the coming years. Due to an increase in demand for biomass, the traditionally used wood residues from sawmills and pulp and paper industry are not sufficient to meet future needs. An extended raw material base consisting of a broad variety of fibrous residues from agriculture and food industries, as well as thermal pre-treatment processes, provides new challenges for the pellet industry. Pellet production has been an established process for several decades, but only in the past five years has there been significant progress made to understand the key factors affecting pelletizing processes. A good understanding about the pelletizing process, especially the processing parameters and their effect on pellet formation and bonding are important for process and product optimization. The present review provides a comprehensive overview of the latest insights into the biomass pelletization processes, such as the forces involved in the pelletizing processes, modeling, bonding, and adhesive mechanisms. Furthermore, thermal pretreatment of the biomass, i.e. torrefaction and other thermal treatment to enhance the fuel properties of biomass pellets are discussed.
- Reviewpp 4424-4450Vishtal, A., and Retulainen, E. (2012). "Deep-drawing of paper and paperboard: The role of material properties," BioRes. 7(3), 4424-4450.AbstractArticlePDF
Fibre-based packaging materials are widely utilized all over the world. They have several important advantages in comparison with fossil-based packaging: biodegradability, recyclability, and renewability. However, fibre-based packaging cannot fully compete with plastic in its barrier properties. Also there are limitations regarding its shapes due to poorer formability. The deep-drawing forming process can be used for the production of advanced three-dimensional shapes from paper-based materials. Formability and related characteristics are essential for deep-drawing of paper-based materials. This paper aims to give an overview of the deep-drawing of paper-based materials with the emphasis on the experienced deformations, on the role of mechanical properties of materials in deep-drawing, and on the typical defects found in the shapes after the forming. Additionally, strategies are proposed to help mitigate common problems in deep-drawing.
- Reviewpp 4377-4399Mohamad Ibrahim, M. N., Sriprasanthi, R. B., Shamsudeen, S., Adam, F., and Bhawani, S. A. (2012). "A concise review of the natural existance, synthesis, properties, and applications of syringaldehyde," BioRes. 7(3), 4377-4399.AbstractArticlePDF
Syringaldehyde is a promising aromatic aldehyde that no longer deserves to remain in obscurity. It possesses worthy bioactive properties and is, therefore, used in pharmaceuticals, food, cosmetics, textiles, pulp and paper industries, and even in biological control applications. Mostly, the synthetic form of syringaldehyde is being used. This review serves as an appraisal of potential research and commercialization of naturally occurring syringaldehyde beyond the scope of the food and cosmetic industries. This article also provides a comprehensive account of the various conventional extraction and chromatographic techniques used in the separation, isolation, and quantification of syringaldehyde. Further, to understand this unique compound, a brief outline on the natural formation of syringaldehyde in lignin is accentuated in this article.
- Reviewpp 4400-4423Suhaily, S. S., Jawaid, M., Abdul Khalil, H. P. S., Mohamed, A. R., and Ibrahim, F. (2012). "A review of oil palm biocomposites for furniture design and applications: Potential and challenges," BioRes. 7(3), 4400-4423.AbstractArticlePDF
This review considers the potential and challenges of using agro-based oil palm biomasses, including the trunk, frond, empty fruit bunch, and palm press fiber biocomposites, for furniture applications. Currently, design and quality rather than price are becoming the primary concern for consumers when buying new furniture. Within this context, this paper focuses on the design of innovative, sustainable furniture from agro-based biocomposites to meet the needs of future population growth and technology. This research also discusses the need for biocomposite materials that do not depend on the growth of populations, but on the growth and development of the economy. This study focuses on globally available agro-based biocomposites, especially those from oil palm biomass: plywood, medium density fiberboard (MDF), wood plastic composite (WPC), laminated veneer lumber (LVL), oriented strand board (OSB), hardboards, and particleboard. Additional positive aspects of biocomposites are their environmentally friendly character, high quality, competitive design, and capacity to improve the value proposition of high-end products. These attributes increase the demand for agro-based biocomposite furniture on the international market.
- Reviewpp 2592-2687Hubbe, M. A., Beck, K. R., O'Neal, W. G., and Sharma, Y. C. (2012). "Cellulosic substrates for removal of pollutants from aqueous systems: A review. 2. Dyes," BioRes. 7(2), 2592-2687.AbstractArticlePDF
Dyes used in the coloration of textiles, paper, and other products are highly visible, sometimes toxic, and sometimes resistant to biological breakdown; thus it is important to minimize their release into aqueous environments. This review article considers how biosorption of dyes onto cellulose-related materials has the potential to address such concerns. Numerous publications have described how a variety of biomass-derived substrates can be used to absorb different classes of dyestuff from dilute aqueous solutions. Progress also has been achieved in understanding the thermodynamics, kinetics, and chemical factors that control the uptake of dyes. Important questions remain to be more fully investigated, such as those involving the full life-cycle of cellulosic substrates that are used for the collection of dyes. Also, more work needs to be done in order to establish whether biosorption should be implemented as a separate unit operation, or whether it ought to be integrated with other water treatment technologies, including the enzymatic breakdown of chromophores.
- Reviewpp 2688-2706Sulaiman, O., Salim, N., Nordin, N. A., Hashim, R., Ibrahim, M., and Sato, M. (2012). "The potential of oil palm trunk biomass as an alternative source for compressed wood," BioRes. 7(2), 2688-2706.AbstractArticlePDF
Compressed wood, which is formed by a process that increases the wood’s density, aims to improve its strength and dimensional stability. Compressed wood can be used in building and construction, especially for construction of walls and flooring. Currently, supplies of wood are becoming limited, and the oil palm tree has become one of the largest plantation species in Malaysia. Oil palm trunk could be an appropriate choice for an alternative source for compressed wood. This paper aims to review the current status of oil palm biomass, including the availability of this tree, in order to illustrate the potential of oil palm biomass as an alternative source for compressed wood. Up to the present there has been insufficient information regarding the manufacturing conditions and properties of compressed wood from oil palm trunk. This paper will cover the background of compressed wood and the possibilities of producing compressed wood using oil palm trunk as a raw material.
- Reviewpp 2582-2591Shi, H., Liu, H., Ni, Y., Yuan, Z., Zou, X., and Zhou, Y. (2012). "Review: Use of optical brightening agents (OBAs) in the production of paper containing high-yield pulps," BioRes. 7(2), 2582-2591.AbstractArticlePDF
The efficiency of optical brightening agents (OBAs), also known as fluorescent whitening agents (FWAs), has long been of interest in the production of uncoated fine paper, particularly in uncoated fine paper grades containing high-yield pulp (HYP). The increasing levels of whiteness and also the increasing HYP substitution in fine papers has made OBA efficiency an important issue. This paper summarizes recent research findings in understanding and enhancing OBA efficiency in fine papers containing HYP, with focus on the main factors affecting OBA efficiency in both wet end and size press application. These factors include the base sheet brightness and whiteness of the pulp, UV competitors, OBA retention, quenching effects, and OBA migration at the size press. Some new technologies to improve OBA efficiency are discussed.
- Reviewpp 2553-2581Popil, R. E. (2012). "Overview of recent studies at IPST on corrugated board edge compression strength: Testing methods and effects of interflute buckling," BioRes. 7(2), 2553-2581.AbstractArticlePDF
Several recent series of investigations were conducted on corrugated board performance in the areas of: loaded container endurance in cyclic humidity, predictive models for edge compression strength (ECT), effects of lightweight facings, measurement of transverse shear rigidity, effects of adhesive level, and out-of-plane crushing on ECT. The course of this program prompted exploration and review of several aspects of ECT testing methods: specimen height, test duration, and fixture-clamping effects. In this review, ECT values are shown to be influenced by the combination of the selected testing technique with the specific structural and strength characteristics of the board being tested. The effect of specimen height on selected single wall C-, E-, F-, and N-flute boards is measured and rationalized using a simplified beam-theory approach. Apparent loss of ECT in a C-flute crushed board is explored to determine whether mitigation is possible by selection or modification of testing method. Investigations of platen speed effects on C-flute substantiate previous work. Lightweight facings on A- and C-flute corrugated boards are observed to display localized buckling, which affects the ECT value. An analytical model that combines the measured bending stiffness of the facings and the compression strengths of the fluting and facings provides an improved predictive accuracy and is applied to a series of laboratory and commercial corrugated boards.
- Reviewpp 2506-2552Johansson, C., Bras, J., Mondragon, I., Nechita, P., Plackett, D., Šimon, P., Svetec, D. G., Virtanen, S., Baschetti, M. G., Breen, C., Clegg, F., and Aucejo, S. (2012). "Renewable fibers and bio-based materials for packaging applications - A review of recent developments," BioRes. 7(2), 2506-2552.AbstractArticlePDF
This review describes the state-of-the-art of material derived from the forest sector with respect to its potential for use in the packaging industry. Some innovative approaches are highlighted. The aim is to cover recent developments and key challenges for successful introduction of renewable materials in the packaging market. The covered subjects are renewable fibers and bio-based polymers for use in bioplastics or as coatings for paper-based packaging materials. Current market sizes and forecasts are also presented. Competitive mechanical, thermal, and barrier properties along with material availability and ease of processing are identified as fundamental issues for sustainable utilization of renewable materials.
- Reviewpp 1366-1382Huber, P., and Carré, B. (2012). "Decolorization of process waters in deinking mills and similar applications: A review," BioRes. 7(1), 1366-1382AbstractArticlePDF
Process waters in deinking mills often feature a strong coloration, due to dyes and pigments released from the recovered paper. This can usually be remediated by pulp bleaching treatment with appropriate chemicals. However, the red shade (from rhodamine dye) is resistant to conventional bleaching treatments. This largely limits the use of deinked pulp in white paper grades. In this review, the available technologies for process water decolorization are discussed (chemical methods, physico-chemical methods and biological treatments). Ozonation of the process water appears to be the most promising technique for decolorization of process water in deinking mills. Other emerging technologies such as photo-catalytic treatment or mineralization by white-rot fungi (after adsorption on low-cost agricultural residues) should be considered as well.
- Reviewpp 5282-5306Wang, Z., Xu, J., and Cheng, J. J. (2011). "Modeling biochemical conversion of lignocellulosic materials for sugar production: A review," BioRes. 6(4), 5282-5306.AbstractPDFTo deeply understand the factors that affect the conversion of lignocellulosic biomass to fermentable sugars, experimental results should be bridged with process simulations. The objective of this paper is to review published research on modeling of the pretreatment process using leading technologies such as dilute acid, alkaline, and steam explosion pretreatment, as well as the enzymatic hydrolysis process for converting lignocellulose to sugars. The most commonly developed models for the pretreatment are kinetic models with assumptions of a first-order dependence of reaction rate on biomass components and an Arrhenius-type correlation between rate constant and temperature. In view of the heterogeneous nature of the reactions involved in the pretreatment, the uses of severity factor, artificial neural network, and fuzzy inference systems present alternative approaches for predicting the behavior of the systems. Kinetics of the enzymatic hydrolysis of cellulosic biomass has been simulated using various modeling approaches, among which the models developed based on Langmuir-type adsorption mechanism and the modified Michaelis-Menten models that incorporate appropriate rate-limiting factors have the most potential. Factors including substrate reactivity, enzyme activity and accessibility, irreversible binding of enzymes to lignin, and enzyme deactivation at high conversion levels, need to be considered in modeling the hydrolysis process. Future prospects for research should focus on thorough understanding of the interactions between biomass reactants and chemicals/enzymes — the key to developing sophisticated models for the entire conversion process.
- Reviewpp 5307-5337Area, M. C., and Cheradame, H. (2011). "Paper aging and degradation: Recent findings and research methods," BioRes. 6(4), 5307-5337.AbstractPDFPaper aging and conservation are matters of concern to those responsible for archives and library collections. Wood-derived fibers are mainly composed of cellulose, hemicelluloses, and lignin, but paper composition can also include additives, such as starch, minerals, and synthetic polymers. Therefore, paper is a multi-component material, and because of its complex and varied nature, research findings in paper chemistry can be difficult to interpret. Deterioration of paper is caused by many factors such as acid hydrolysis, oxidative agents, light, air pollution, or the presence of microorganisms. The origin of the cellulosic material, as well as pulping and papermaking procedures, additives, and storage conditions play a crucial role. The chemical changes occurring within paper thus involve multi-parameter processes. The purpose of this review, which mainly focuses on the most recent decade, is to provide a description of the more important changes produced by aging and an update of the new tools available for the study of paper deterioration and its conservation.
- Reviewpp 5260-5281Paridah, M. T., Ahmed, A. B., SaifulAzry, S. O. A., and Ahmed, Z. (2011). "Retting process of some bast plant fibers and its effect on fibre quality: A review," BioRes. 6(4), page #s to be assigned Nov. 2011.AbstractPDFRetting is the main challenge faced during the processing of bast plants for the production of long fibre. The traditional methods for separating the long bast fibres are by dew and water retting. Both methods require 14 to 28 days to degrade the pectic materials, hemicellulose, and lignin. Even though the fibres produced from water retting can be of high quality, the long duration and polluted water have made this method less attractive. A number of other alternative methods such as mechanical decortication, chemical, heat, and enzymatic treatments have been reported for this purpose with mixed findings. This paper reviews different types of retting processes used for bast plants such as hemp, jute, flax, and kenaf, with an emphasis on kenaf. Amongst the bast fibre crops, kenaf apparently has some advantages such as lower cost of production, higher fibre yields, and greater flexibility as an agricultural resource, over the other bast fibres. The fibres produced from kenaf using chemical retting processes are much cleaner but low in tensile strength. Enzymatic retting has apparent advantages over other retting processes by having significantly shorter retting time and acceptable quality fibres, but it is quite expensive.
- Reviewpp 5224-5259Isroi, Millati, R., Syamsiah, S., Niklasson, C., Cahyanto, M. N., Lundquist, K., and Taherzadeh, M. J. (2011). "Biological pretreatm139086ent of lignocelluloses with white-rot fungi and its applications: A review," BioRes. 6(4), 5224-5259.AbstractPDFLignocellulosic carbohydrates, i.e. cellulose and hemicellulose, have abundant potential as feedstock for production of biofuels and chemicals. However, these carbohydrates are generally infiltrated by lignin. Breakdown of the lignin barrier will alter lignocelluloses structures and make the carbohydrates accessible for more efficient bioconversion. White-rot fungi produce ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase) and efficiently mineralise lignin into CO2 and H2O. Biological pretreatment of lignocelluloses using white-rot fungi has been used for decades for ruminant feed, enzymatic hydrolysis, and biopulping. Application of white-rot fungi capabilities can offer environmentally friendly processes for utilising lignocelluloses over physical or chemical pretreatment. This paper reviews white-rot fungi, ligninolytic enzymes, the effect of biological pretreatment on biomass characteristics, and factors affecting biological pretreatment. Application of biological pretreatment for enzymatic hydrolysis, biofuels (bioethanol, biogas and pyrolysis), biopulping, biobleaching, animal feed, and enzymes production are also discussed.
- Reviewpp 3569-3584Li, B., Li, H., Zha, Q., Bandekar, R., Alsaggaf, A., and Ni, Y. (2011). "Review: Effects of wood quality and refining process on TMP pulp and paper quality," BioRes. 6(3), 3569-3584.AbstractArticlePDF
For the thermomechanical pulping (TMP) process both wood chip quality and the refining process have important effects on the resulting pulp and paper quality. Properties of wood raw material give a framework for final pulp properties. During TMP refining the specific energy consumption and refining intensity strongly impact fibre and pulp qualities. Increasing specific energy consumption benefits the development of fibres and improves their properties. However, high intensity refining tends to shorten the fibres and produces more fines content when compared with low intensity refining. This review focuses on the influence of key variables of chip qualities and the refining process on TMP pulp and paper qualities.
- Reviewpp 3585-3620Sasso, C., Beneventi, D., Zeno, E., Chaussy, D., Petit-Conil, M., and Belgacem, N. (2011). "Polypyrrole and polypyrrole/wood-derived materials conducting composites: A review," BioRes. 6(3), 3585-3620.AbstractArticlePDF
Wood and cellulose derivatives, in both fibrous and water-soluble macromolecular form, are emerging as outstanding candidates for organic electronics applications due to their large-scale availability, low cost, and easy processability. Paper and wood fibre-based derivatives are considered to be materials of choice as supports for communication world-wide. The interest in producing inexpensive and universally available conducting polymer/cellulose fibres substrates resides in the possibility of creating new materials that can be used for a broad range of advanced applications. For instance, PPy/cellulose fibres composites can be used for the preparation of energy storage devices thanks to the conjugation of the high specific area of cellulose fibres and the electrochemical properties of PPy. Other possible applications of such composites are in the area of the antistatic materials, sensors, electromagnetic interference shielding materials, smart packaging, and tissues. Concerning the woody polymers, some of them (i.e. cellulose derivatives) also exhibit biocompatibility, as well as film-forming properties and transparency. In combination with the electrical properties of PPy, these features make PPy/macromolecular cellulose composites suitable for applications as displays, lighting, and photovoltaics. Due to their chemical structure, macromolecular wood derivatives have been proposed with success as enhancing conductivity additives in Py polymerisation. The aim of the present review is to provide an overview of PPy chemistry and of the most relevant advances attained in the production of PPy/wood derived materials conducting composites.
- Reviewpp 3547-3568Vishtal, A., and Kraslawski, A. (2011). "Challenges in industrial applications of technical lignins, BioRes. 6(3), 3547-3568.AbstractArticlePDF
The primary aim of modern biorefineries is the efficient conversion of lignocellulosic materials into valuable products. Sugars and oils can be converted into valuable chemicals, but processing of lignin is still a challenge. A vast amount of lignin is incinerated to produce process steam and energy, and only a very small part is used for the production of value-added products. Technical lignins are isolated as by-streams in lignocellulosic refineries, e.g., as kraft, soda, organosolv, and hydrolysis lignins, as well as lignosulphonates. They have a modified structure and contain impurities that are dependent on the processing method. The structure and the composition of technical lignins restrict their subsequent applications. This paper reviews limiting factors in utilization of technical lignins. Four major classes of problems are identified, and approaches to overcoming these problems are suggested.
- Reviewpp 3515-3525Hu, L., Pan, H., Zhou, Y., and Zhang, M. (2011). "Methods to improve lignin's reactivity as a phenol substitute and as replacement for other phenolic compounds: A brief review," BioRes. 6(3), 3515-3525.AbstractArticlePDF
Lignin is readily available as a by-product from the pulp and paper industry. It is considered to be a promising substitute for phenol in phenol-formaldehyde (PF) resin synthesis, given the increasing concerns of the shortage of fossil resources and the environmental impact from petroleum-based products. One hurdle that prevents the commercial utilization of lignin is its low reactivity due to its chemical structure. Many efforts have been made to improve its reactivity by modification and/or depolymerization of lignin molecules. Methylolation and phenolation are the two most studied modification approaches aimed at introducing reactive functional groups to lignin molecules. Modified lignin from these two methods could partially replace phenol in PF resin synthesis. Demethylation of lignin could effectively increase the reactivity of lignin by forming catechol moieties in the lignin macromolecule. Other methods, including reduction, oxidation, and hydrolysis, have also been studied to improve the reactivity of lignin as well as to produce phenolic compounds from lignin. Most current methods of lignin modification are not economically attractive. One can expect that efforts will be continued, aimed at improving the utilization of lignin for value-added products.
- Reviewpp 3526-3546Kumar, P., Negi, Y. S., and Singh, S. P. (2011). "Filler loading in the lumen or/and cell wall of fibers - A literature review," BioRes. 6(3), 3526-3546.AbstractArticlePDF
A review of the literature reveals potential advantages that papermakers can achieve by placing minerals in the lumens or cell walls of fibers before the pulp is formed into paper. Loading of filler into the fiber lumen by mechanical deposition or within the cell wall by in-situ precipitation has been reported to generally result in a moderate reduction in light scattering coefficient and increased strength properties of laboratory handsheets, as well as in paper manufactured with pilot plant equipment, when compared to conventional addition of filler. However, there are some exceptions to this general observation, where the fiber loading is reported to decrease the tensile strength of paper. Some related effects can be achieved by either precipitating mineral onto fiber surfaces or co-flocculating mineral particles with cellulosic fines. Challenges remain with respect to the implementation of fiber-loading concepts at a commercial scale. Also, there is a need for further research aimed at establishing high-end applications in which it may be an advantage to load cellulosic fiber cell walls or lumens with minerals or other substances.
- Reviewpp 2161-2287Hubbe, M. A., Hasan, S. H., and Ducoste, J. J. (2011). "Cellulosic substrates for removal of pollutants from aqueous systems: A review. 1. Metals," BioRes. 6(2), 2161-2287.AbstractArticlePDF
Recent years have seen explosive growth in research concerning the use of cellulosic materials, either in their as-recieved state or as modified products, for the removal of heavy metal ions from dilute aqueous solutions. Despite highly promising reports of progress in this area, important questions remain. For instance, it has not been clearly established whether knowledge about the composition and structure of the bioadsorbent raw material is equally important to its availability at its point of use. Various physical and chemical modifications of biomass have been shown to boost the ability of the cellulose-based material to bind various metal ions. Systems of data analysis and mechanistic models are described. There is a continuing need to explain the mechanisms of these approaches and to determine the most effective treatments. Finally, the article probes areas where more research is urgently needed. For example, life cycle analysis studies are needed, comparing the use of renewable biosorbents vs. conventional means of removing toxic metal ions from water.
- Reviewpp 901-917Wan Daud, W. R., and Law, K.-N. (2011). "Oil palm fibers as papermaking material: Potentials and challenges," BioRes. 6(1),901-917.AbstractArticlePDF
This paper reviews the physical and chemical characteristics of fibers from the stem, fronds, and empty fruit bunches of oil palm tree in relation to their papermaking properties. Challenges regarding the use of this nonwood material for papermaking are raised, and possible solutions to them are given. A vision for the complete utilization of oil palm biomass is also outlined.
- Reviewpp 2808-2854Hubbe, M. A., Nazhad, M., and Sánchez, C. (2010). "Composting as a way to convert cellulosic biomass and organic waste into high-value soil amendments: A review," BioRes. 5(4), 2808-2854.AbstractPDFPlant-derived cellulosic materials play a critical role when organic wastes are composted to produce a beneficial amendment for topsoil. This review article considers publications dealing with the science of composting, emphasizing ways in which the cellulosic and lignin components of the composted material influence both the process and the product. Cellulose has been described as a main source of energy to drive the biological transformations and the consequent temperature rise and chemical changes that are associated with composting. Lignin can be viewed as a main starting material for the formation of humus, the recalcitrant organic matter that provides the water-holding, ion exchange, and bulking capabilities that can contribute greatly to soil health and productivity. Lignocellulosic materials also contribute to air permeability, bulking, and water retention during the composting process. Critical variables for successful composting include the ratio of carbon to nitrogen, the nature of the cellulosic component, particle size, bed size and format, moisture, pH, aeration, temperature, and time. Composting can help to address solid waste problems and provides a sustainable way to enhance soil fertility.
- Reviewpp 2765-2807Rani, M., Agarwal, A., and Negi, Y. S. (2010). "Review: Chitosan based hydrogel polymeric beads - As drug delivery system," BioRes. 5(4), page #s pending completion of issue.AbstractPDFChitosan obtained by alkaline deacetylation of chitin is a non-toxic, biocompatible, and biodegradable natural polymer. Chitosan-based hydrogel polymeric beads have been extensively studied as micro- or nano-particulate carriers in the pharmaceutical and medical fields, where they have shown promise for drug delivery as a result of their controlled and sustained release properties, as well as biocompatibility with tissue and cells. To introduce desired properties and enlarge the scope of the potential applications of chitosan, graft copolymerization with natural or synthetic polymers on it has been carried out, and also, various chitosan derivatives have been utilized to form beads. The desired kinetics, duration, and rate of drug release up to therapeutical level from polymeric beads are limited by specific conditions such as beads material and their composition, bead preparation method, amount of drug loading, drug solubility, and drug polymer interaction. The present review summarizes most of the available reports about compositional and structural effects of chitosan-based hydrogel polymeric beads on swelling, drug loading, and releasing properties. From the studies reviewed it is concluded that chitosan-based hydrogel polymeric beads are promising drug delivery systems.
- Reviewpp 1955-2023Baty, J. W., Maitland, C. L., Minter, W., Hubbe, M. A., and Jordan-Mowery, S. K. (2010). "Deacidification for the conservation and preservation of paper-based works: A review," BioRes. 5(3), 1955-2023.AbstractPDFEmbrittlement threatens the useful lifetime of books, maps, manuscripts, and works of art on paper during storage, circulation, and display in libraries, museums, and archives. Past studies have traced much of the embrittlement to the Brønsted-acidic conditions under which printing papers have been made, especially during the period between the mid 1800s to about 1990. This article reviews measures that conservators and collection managers have taken to reduce the acidity of books and other paper-based materials, thereby decreasing the rates of acid-catalyzed hydrolysis and other changes leading to embrittlement. Technical challenges include the selection of an alkaline additive, selecting and implementing a way to distribute this alkaline substance uniformly in the sheet and bound volumes, avoiding excessively high pH conditions, minimizing the rate of loss of physical properties such as resistance to folding, and avoiding any conditions that cause evident damage to the documents one is trying to preserve. Developers have achieved considerable progress, and modern librarians and researchers have many procedures from which to choose as a starting point for further developments.
- Reviewpp 1311-1325Bajpai, P. K. (2010). "Solving the problems of recycled fiber processing with enzymes," BioRes. 5(2), 1311-1325.AbstractPDFThe pulp and paper industry has started applying new, ecologically sound technology (biotechnology) in its manufacturing processes. Many interesting enzymatic applications have been proposed. Implemented technologies tend to change the existing industrial process as little as possible. Enzymes have great potentials in solving many problems associated with the use of recycled fiber, especially related to deinking, drainability, hornification, refining, and stickies. Based on the promising results of mill-scale trials, several mills in the world have started using enzymes for deinking. The potentials of cellulase enzymes have also been demonstrated for reducing the energy requirement in pulp refining, improving the machine runnability and stickies control when using recycled fiber. They have the important benefits in that they can be considered a “green” product. They are natural occurring compounds with little adverse impact on the environment. This paper deals with the importance of recycling of paper, problems associated with the recycling, and potentials of enzymes in solving these problems. A few case studies have also been included.
- Reviewpp 499-506Papadopoulos, A. N. (2010). "Chemical modification of solid wood and wood raw material for composites produciton with linear chain carboxylic acid anhydrides: A brief review," BioRes. 5(1), 499-506.AbstractPDFThis paper reviews recent results in the field of chemical modification of wood with linear chain anhydrides. Though the main focus is on work performed by the author, this is described in the context of related progress in the field. The combined research has demonstrated the effectiveness of chemical modification applied to solid wood and wood raw material for composites production in overcoming the main disadvantages of wood. Wood samples and wood chips/strands have been chemically modified with a series of anhydrides at equivalent levels of modification, under identical conditions, and the question was to determine which is the primary factor controlling the biological durability, the degree of cell wall bulking by the bonded adduct, or the extent of hydroxyl substitution. The results have clearly indicated that the degree of cell wall bulking caused by the adduct, rather than the extent of hydroxyl substitution, is the primary factor controlling the biological durability and water vapour sorption. Despite the large difference in OH substitution level, reaction with different anhydrides results in the same level of protection against decay, marine borers and termites, and in the same level of water vapour sorption. These observations suggest that the mechanism of protection is not chemical/biochemical in origin, but relates to the bulking of the cell wall by the reacted adduct.
- Reviewpp 1736-1792Hubbe, M. A., and Bowden, C. (2009). "Handmade paper: A review of its history, craft, and science," BioRes. 4(4), 1736-1792.AbstractPDFFor over 2000 years the manual craft of papermaking has been practiced all over the world utilizing a variety of techniques. This review describes the evolution of hand papermaking and its cultural significance. Paper’s evolution has been shaped by the structure and chemical composition of the fibers. Almost every aspect of modern papermaking technology has been foreshadowed by traditional practices. Such practices were passed down for many generations within families of papermakers. The main sources of cellulosic fiber evolved as the ancient craft migrated from its birthplace in China to Korea and Japan, the Islamic world, and then to Europe and America. Though most paper made today comes from automated, continuous production systems, handmade paper has enjoyed a resurgence, both as a traditional craft and as an art-form. In addition, traditional papermaking methods can provide insights to help in modern applications involving cellulosic fibers.
- Reviewpp 1718-1735Virkajärvi, I., Niemelä, M. V., Hasanen, A., and Teir, A. (2009). "Cellulosic ethanol via biochemical processing poses a challenge for developers and implementors," BioRes. 4(4), 1718-1735.AbstractPDFIn the future liquid biofuels will need to be renewable, sustainable, as well as technically and economically viable. This paper provides an overview of the challenges that the biochemical production of cellulosic ethanol process still faces. The main emphasis of the paper is on challenges that emerge from the scale of liquid biofuel production. These challenges include raw material availability, other consumables, and side stream handling. The pretreatment, C5 fermentation, and concentration of sugars in processing need improvements, too. Sustainability issues and greenhouse gas reduction also pose a challenge for implementation and require development of internationally recognized sustainability principles and standards, and certification of sustainable operation. Economics of cellulosic ethanol processes are still also an area under development and debate. Yet, the Energy Independence and Security Act mandate together with the European Union Renewable Energy Directive and other local targets are driving the development and implementation forward towards more significant contribution of biofuels in the transportation sector.
- Reviewpp 1694-1717Madhavi, V., and Lele, S. S. (2009)."Laccase: Properties and applications," BioRes. 4(4), 1694-1717.AbstractPDFLaccases (benzenediol:oxygen oxidoreductase, EC 220.127.116.11) are multi-copper oxidases that are widely distributed among plants, insects, and fungi. They have been described in different genera of ascomycetes, some deuteromycetes, and mainly in basidiomycetes. These enzymes catalyze the one-electron oxidation of a wide variety of organic and inorganic substrates, including mono-, di-, and polyphenols, aminophenols, methoxyphenols, aromatic amines, and ascorbate, with the concomitant four electron reduction of oxygen to water. Laccase is currently the focus of much attention because of its diverse applications, such as delignification of lignocellulosics, crosslinking of polysaccha-rides, bioremediation applications, such as waste detoxification, and textile dye transformation, food technologic uses, personal and medical care applications, and biosensor and analytical applications. This review helps to understand the properties of this important enzyme for efficient utilization for its biotechnological and environmental applications.
- Reviewpp 1210-1221Muszyński, L. (2009). "Imaging wood plastic composites (WPCs): X-ray computed tomography, a few other promising techniques, and why we should pay attention," BioRes. 4(3), 1210-1221.AbstractPDFWood plastic composites are complex, anisotropic, and heterogeneous materials. A key to increasing the share of the WPC materials in the market is developing stronger, highly engineered WPCs characterized by greater structural performance and increased durability. These are achieved by enhanced manufacturing processes, more efficient profile designs, and new formulations providing better interaction between the wood particles and the plastic matrix. Significant progress in this area is hard to imagine without better understanding of the composite performance and internal bond durability on the micro-mechanical level, and reliable modeling based on that understanding. The objective of this paper is to present a brief review of promising material characterization techniques based on advanced imaging technologies and inverse problem methodology, which seem particularly suitable for complex heterogeneous composites. Full-field imaging techniques and specifically X-ray computed tomography (CT) combined with numerical modeling tools have a potential to advance the fundamental knowledge on the effect of manufacturing parameters on the micromechanics of such materials and their response to loads and environmental exposure.
- Reviewpp 1222-1262Wu, N., Hubbe, M. A., Rojas, O. J., and Park, S. (2009). "Permeation of polyelectrolytes and other solutes into the pore spaces of water-swollen cellulose: A review," BioRes. 4(3), 1222-1262.AbstractPDFThe rate and extent of transport of macromolecules and other solutes into cellulosic materials and fibers have important applications in such fields as papermaking, textiles, medicine, and chromatography. This review considers how diffusion and flow affect permeation into wood, paper, and other lignocellulosic materials. Because pore sizes within such materials can range from nanometers to millimeters, a broad perspective will be used, also considering some publications related to other porous materials. Factors that limit the rate or extent of polymer or other solute transport into pores can involve thermodynamics (affecting the driving motivation for permeation), kinetics (if there is insufficient time for the system to come to equilibrium), and physical barriers. Molecular flow is also affected by the attributes of the solute, such as molecular mass and charge, as well as those of the substrate, such as the pore size, interconnectedness, restricted areas, and surface characteristics. Published articles have helped to clarify which of these factors may have a controlling influence on molecular transport in different situations.
- Reviewpp 1190-1209Shen, J., Song, Z., Qian, X., and Liu, W. (2009). "Modification of papermaking grade fillers: A brief review," BioRes. 4(3), 1190-1209.AbstractPDFThe use of fillers in paper products can provide cost and energy savings, improved paper properties, increased productivities, and specifically desired paper functionalities. There are many problems associated with the use of fillers, such as unsuitability of calcium carbonate fillers in acid papermaking, negative effects of filler loading on paper strength, sizing, and retention, and tendencies of fillers to cause abrasion and dusting. In order to solve these problems and to make better use of fillers, many methods have been proposed, among which filler modification has been a hot topic. The available technologies of filler modification mainly include modification with inorganic substances, modification with natural polymers or their derivatives, modification with water-soluble synthetic polymers, modification with surfactants, modification with polymer latexes, hydrophobic modification, cationic modification, surface nano-structuring, physical modification by compressing, calcination or grinding, and modification for use in functional papers. The methods of filler modification can provide improved acid tolerant and optical properties of fillers, enhanced fiber-filler bonding, improved filler retention and filler sizabilities, alleviated filler abrasiveness, improved filler dispersability, and functionalization of filled papers. Filler modification has been an indispensable way to accelerate the development of high filler technology in papermaking, which is likely to create additional benefits to papermaking industry in the future.
- Reviewpp 850-906Hubbe, M. A., Nanko, H., and McNeal, M. R. (2009). "Retention aid polymer interactions with cellulosic surfaces and suspensions: A review," BioRes. 4(2), 850-906.AbstractPDFRetention aids can be defined as very-high-mass, water-soluble polymers that are added to cellulosic fiber slurries before the formation of paper in order to improve the efficiency with which fine particles, including cellulosic fines, are retained in the paper product. Optimization of retention aid performance can be a key to achieving efficient and environmentally responsible papermaking objectives. This article reviews various published theories related to retention aid use. Findings related to three main classes of retention aid polymers are considered: cationic acrylamide copolymers (cPAM), anionic acrylamide copolymers (aPAM), and polyethylene oxide (PEO). While many aspects of the interactions of each of these classes of retention aid products can be understood based on colloid chemistry principles, further research is needed in order to more fully bridge the gap between theory and practice.
- Reviewpp 835-849Lu, J., Chorney, M., and Peterson, L. (2009). "Sustainable trailer flooring," BioRes. 4(2), 835-849.AbstractPDFDifferent trailer flooring materials, including wood-based, aluminum, steel, and synthetic plastic floors, were evaluated in accordance with their durability and sustainability to our natural environment. Wood-based trailer flooring is an eco-friendly product. It is the most sustainable trailer flooring material compared with fossil fuel-intensive steel, aluminum, and plastics. It is renewable and recyclable. Oak, hard maple, and apitong are strong and durable hardwood species that are currently extensively used for trailer flooring. For manufacture, wood-based flooring is higher in energy efficiency and lower in carbon emission than steel, aluminum and plastics. Moreover, wood per se is a natural product that sequesters carbon. Accordingly, using more wood-based trailer flooring is effective to reduce global warming.
- Reviewpp 825-834Han, S., Li, J., Zhu, S., Chen, R., Wu, Y., Zhang, X., and Yu, Z. (2009). "Potential applications of ionic liquids in wood related industries," BioRes. 4(2), 825-834.AbstractPDFThe use of ionic liquids (ILs) has provided a new platform for efficient utilization of wood. In this paper, applications of ILs in wood-related industries are reviewed. First, the dissolution of wood in ILs and its application are described. Then the ILs used for wood preservation and improvement of wood anti-electrostatic and fire-proof properties are illustrated. Finally, “green” wood processing with ILs is discussed. Although some basic studies of ILs, such as their economical syntheses and toxicology are eagerly needed and some engineering problems still exist, research for application of ILs in wood-related industries has made great progress in recent years.
- Reviewpp 405-451Hubbe, M. A., Chen, H., and Heitmann, J. A. (2009). "Permeability reduction phenomena in packed beds, fiber mats, and wet webs of paper exposed to flow of liquids and suspensions: A review," BioRes. 4(1), 405-451.AbstractPDFFilter media, including those prepared from cellulosic materials, often suffer from permeability loss during continued use. To help understand such issues, one can take advantage of an extensive body of related research in such fields as industrial filtration, water purification, enhanced oil recovery, chromatography, paper manufacture, and the leaching of pollutants from impoundments. Though the mechanisms that appear to govern permeability-loss phenomena depend a lot on the details of various applications, the published research has revealed a number of common features. In particular, flow through a porous bed or fiber mat can be markedly reduced by deposition of particles or colloidal matter in positions that either block or partially restrict fluid flow. Progress has been achieved in the development of mechanistic models, as well as the use of such models in numerical simulations to explain various experimental findings. Further research of this type needs to be applied to cellulosic materials, which tend to be much more elongated in comparison to the bed materials and suspended matter considered most often by most researchers active in research related to permeability loss.
- Reviewpp 341-369Gronowska, M., Joshi, S., and MacLean, H. L. (2009). "A review of U.S. and Canadian biomass supply studies," BioRes. 4(1), 341-369.AbstractPDFAn improved understanding of lignocellulosic biomass availability is needed to support proposed expansion in biofuel production. Fifteen studies that estimate availability of lignocellulosic biomass quantities in in the U.S. and/or Canada are reviewed. Sources of differences in study methods and assumptions and resulting biomass quantities are elucidated. We differentiate between inventory studies, in which quantities of biomass potentially available are estimated without rigorous consideration of the costs of supply, versus economic studies, which take into consideration various opportunity costs and competition. The U.S. economic studies, which included reasonably comprehensive sets of biomass categories, estimate annual biomass availability to range from 6 million to 577 million dry metric tonnes (dry t), depending on offered price, while estimates from inventory studies range from 190 million to 3849 million dry t. The Canadian inventory studies, which included reasonably comprehensive sets of biomass categories, estimate availability to range from 64 million green t to 561 million dry t. The largest biomass categories for the U.S. are energy crops and agricultural residues, while for Canada they are expected to be energy crops and logging residues. The significant differences in study estimates are due in large part to the number of biomass categories included, whether economic considerations are incorporated, assumptions about energy crop yields and land areas, and level of optimism of assumptions of the study.
- Reviewpp 370-404Esteves, B. M., and Pereira, H. M. (2009). "Wood modification by heat treatment: A review," BioRes. 4(1), 370-404.AbstractPDFWood heat treatment has increased significantly in the last few years and is still growing as an industrial process to improve some wood properties. The first studies on heat treatment investigated mainly equilibrium moisture, dimensional stability, durability and mechanical properties. Mass loss, wettability, wood color, and chemical transformations have been subsequently extensively studied, while recent works focus on quality control, modeling, and study the reasons for the improvements. This review explains the recent interest on the heat treatment of wood and synthesizes the major publications on this subject on wood properties, chemical changes, wood uses, and quality control.
- Reviewpp 1419-1491Hubbe, M. A., and Rojas, O. J. (2008). "Colloidal stability and aggregation of lignocellulosic materials in aqueous suspension: A review," BioRes. 3(4), 1419-1491.AbstractPDFAqueous dispersions of lignocellulosic materials are used in such fields as papermaking, pharmaceuticals, and preparation of cellulose-based composites. The present review article considers published literature dealing with the ability of cellulosic particle dispersions (fiber, fines, nanorods, etc.) to either remain well dispersed or to agglomerate in response to changes in the composition of the supporting electrolyte solution. In many respects, the colloidal stability and coagulation of lignocellulosics can be understood in terms of well-known concepts, including effects due to osmotic pressure arising from overlapping electrostatic double layers at the charged surfaces. Details of the morphology and surface properties of lignocellulosic materials give rise to a variety of colloidal behaviors that make them unique. Adjustments in aqueous conditions, including the pH, salt ions (type and valence), polymers (charged or uncharged), and surfactants can be used to control the dispersion stability of cellulose, lignin, or wood-extractive materials to serve a variety of applications.
- Reviewpp 1403-1418Ioelovich, M. (2008). "Cellulose as a nanostructured polymer: A short review," BioRes. 3(4), 1403-1418.AbstractPDFCellulose has a complex, multi-level supermolecular architecture. This natural polymer is built from superfine fibrils having diameters in the nano scale, and each such nanofibril contains ordered nanocrystallites and low-ordered nano-domains. In this review, the nano-structure of cellulose and its influence on various properties of the polymer is discussed. In particular, the ability of nano-scale crystallites to undergo lateral co-crystallization and aggregation, as well as to undergo phase transformation through dissolution, alkalization, and chemical modification of cellulose has been the subject of investigation. The recent investigations pave the way for development of highly reactive cellulosic materials. Methods for preparation nanofibrillated cellulose and free nano-particles are described. Some application areas of the nanostruc-tured and nano-cellulose are discussed.
- Reviewpp 1377-1402Dhiman, S. S., Sharma, J., and Battan, B. (2008). "Industrial applications and future prospects of microbial xylanases: A review," BioRes. 3(4), 1377-1402.AbstractPDFMicrobial enzymes such as xylanases enable new technologies for industrial processes. Xylanases (xylanolytic enzyme) hydrolyze complex polysaccharides like xylan. Research during the past few decades has been dedicated to enhanced production, purification, and characterization of microbial xylanase. But for commercial applications detailed knowledge of regulatory mechanisms governing enzyme production and functioning should be required. Since application of xylanase in the commercial sector is widening, an understanding of its nature and properties for efficient and effective usage becomes crucial. Study of synergistic action of multiple forms and mechanism of action of xylanase makes it possible to use it for bio-bleaching of kraft pulp and for desizing and bio-scouring of fabrics. Results revealed that enzymatic treatment leads to the enhancement in various physical properties of the fabric and paper. This review will be helpful in determining the factors affecting xylanase production and its potential industrial applications in textile, paper, pulp, and other industries.
- Reviewpp 910-928Esteban, L. S., Ciria, P., and Carrasco, J. E. (2008). "An assessment of relevant methodological elements and criteria for surveying sustainable agricultural and forestry biomass byproducts for energy purposes," BioRes. 3(3), 910-928.AbstractPDFResource assessment is a necessary step for any project, plan, or future energy prospectus involving renewable energy sources. The assessment of biomass and, in particular, the so-called forest and agricultural field residues, faces particular methodological difficulties due to the scarcity and heterogeneity of the data sources. For agricultural residues such as cereal straw, bagasses, etc., the residue to product ratios (RPR) are the key data needed for the estimations. In the present work the values of these product ratios reported in the literature are surveyed and are seen to vary greatly, depending on the reporting source. Some methodological procedures for obtaining RPR values are considered, and guidelines for conducting the resource evaluation are indicated. For the estimation of forest field biomass resources a methodological procedure based on the different stand stages along a forest rotation is presented. The main steps of this methodology are based on the availability of basic quantitative data from forest stands and the assumption of different silvicultural operations during the stand rotations. Environmental constraints should be observed in biomass resource assessments. However, the lack of clear recommendations concerning biomass removal in different forest soil and climate conditions suggest that more research is required to assess the sustainability of biomass harvest. Chemical characterization of some of the most representative biomass materials is also presented.
- Reviewpp 929-980Hubbe, M. A., Rojas, O. J., Lucia, L. A., and Sain, M. (2008). "Cellulosic nanocomposites: A review," BioRes. 3(3), 929-980.AbstractPDFBecause of their wide abundance, their renewable and environmentally benign nature, and their outstanding mechanical properties, a great deal of attention has been paid recently to cellulosic nanofibrillar structures as components in nanocomposites. A first major challenge has been to find efficient ways to liberate cellulosic fibrils from different source materials, including wood, agricultural residues, or bacterial cellulose. A second major challenge has involved the lack of compatibility of cellulosic surfaces with a variety of plastic materials. The water-swellable nature of cellulose, especially in its non-crystalline regions, also can be a concern in various composite materials. This review of recent work shows that considerable progress has been achieved in addressing these issues and that there is potential to use cellulosic nano-components in a wide range of high-tech applications.
- Reviewpp 627-665Hubbe, M. A., Pawlak, J. J., and Koukoulas, A. A. (2008). "Paper's appearance: A review," BioRes. 3(2), 627-665.AbstractPDFThis review article highlights progress in understanding the optical properties of paper. Paper’s appearance can be defined in terms of its opacity, brightness, color, fluorescent properties, gloss, and various quantities related to its uniformity. The phenomena that give rise to paper’s optical properties, especially its ability to scatter and absorb visible light, are highly dependent on paper’s structure and its chemical composition. In an effort to engineer low-cost products having relative high opacity and brightness, it is necessary to optimize the material selection and processing conditions. The dimensions of solid materials and void structures within the paper are key factors for optimizing the optical properties. In addition, additives including bleaching agents, mineral particles, dyes, and fluorescent whitening agents can impact paper’s optical properties Paper’s appearance depends, in subtle ways, on the processes of its manufacture.
- Reviewpp 602-626Frybort, S., Mauritz, R., Teischinger, A., and Müller, U. (2008). "Cement bonded composites - A mechanical review," BioRes. 3(2), 602-626.AbstractPDFOver the last years promising cement bonded wood composites for structural purposes have evolved. Durability, toughness, high dimen-sional stability, resistance against environmental influences such as biodegradation or weathering but also availability of the raw material as well as economic factors are features which can make cement-bonded composites superior to conventionally bonded composites. This paper reviews the relationship of diverse parameters, including density and particle size on mechanical and physical properties of cement bonded composites, based on published sources from the last 60 years. For general and recent information about bonding mechanisms, compatibility and setting problems, determination and improvement of compatibility, the used raw materials as well as accelerators are discussed. The main part deals with failure mechanisms in connection with several production parameters. Furthermore, the influence of particle size and geometry, orientation of the particles, cement-wood ratio and the effect of accelerators and treatment of the particles on modulus of elasticity, modulus of rupture as well as thickness swelling are discussed.
- Reviewpp 576-601Liebert, T., and Heinze, T. (2008). "Interaction of ionic liquids with polysaccharides. 5. Solvents and reaction media for the modification of cellulose," BioRes. 3(2), 576-601.AbstractPDFThe use of ionic liquids (ILs) in the field of cellulose chemistry opens up a broad variety of new opportunities. Besides the regeneration of the biopolymer to fibers, films, and beads, this new class of cellulose solvents is particularly useful for the homogeneous chemical modification of the polysaccharide. In this review, the potential of ILs as a reaction medium for the homogeneous cellulose functionalization is discussed. It is shown that numerous conversions proceed very efficiently and the ILs may be recycled. But it is also demonstrated that some side reactions have to be considered.
- Reviewpp 270-294Hu, G., Heitmann, J. A., and Rojas, O. J. (2008). "Feedstock pretreatment strategies for producing ethanol from wood, bark, and forest residues," BioRes. (3(1), 270-294.AbstractPDFEnergy and environmental issues are among the major concerns facing the global community today. Transportation fuel represents a large proportion of energy consumption, not only in the US, but also world-wide. As fossil fuel is being depleted, new substitutes are needed to provide energy. Ethanol, which has been produced mainly from the fermentation of corn starch in the US, has been regarded as one of the main liquid transportation fuels that can take the place of fossil fuel. However, limitations in the supply of starch are creating a need for different substrates. Forest biomass is believed to be one of the most abundant sources of sugars, although much research has been reported on herbaceous grass, agricultural residue, and municipal waste. The use of biomass sugars entails pretreatment to disrupt the lignin-carbohydrate complex and expose carbohydrates to enzymes. This paper reviews pretreatment technologies from the perspective of their potential use with wood, bark, and forest residues. Acetic acid catalysis is suggested for the first time to be used in steam explosion pretreatment. Its pretreat-ment economics, as well as that for ammonia fiber explosion pretreatment, is estimated. This analysis suggests that both are promising techniques worthy of further exploration or optimization for commercialization.
- Reviewpp 255-269Gonzalez, R. W., Saloni, D., Dasmohapatra, S., and Cubbage, F. (2008). "South America: Industrial roundwood supply potential," BioRes. 3(1), 255-269.AbstractPDFSouth America has substantial potential to expand its forest plantations and raw material supply. From 1997 to 2005, South America had a high annual growth rate in the production of industrial roundwood, with Brazil and Chile being the most important countries. In the same period, Asia had the only negative regional production growth rate in the world, and China became the largest round wood importer in the world. This paper summarizes the status of production, consumption, imports, and exports of industrial roundwood and forest products in South America. Produc-tion and exports from South America have continually increased at annual growth rates exceeding the forestry sector in general and the U.S. in particular. Based on timber growing investments to date, a strong timber production and forest products manufacturing sector has developed in the Southern Cone countries of Chile, Brazil, Argentina, and Uruguay, and is increasing in other countries in Latin America. There will be continued opportunities for forest plantations and new manufacturing facilities throughout South America, tempered somewhat by perceived country financial and political risks. These opportunities will allow South America to increase its share of world production and increase imports to North America and to Asia. PDF
- Reviewpp 789-811Oltean, L., Teischinger, A., and Hansmann, C. (2007). "Influence of temperature on cracking and mechanical properties of wood during wood drying - A review," BioRes. 2(4), 789-811.AbstractPDFThe occurrence of cracks and loss of mechanical properties are major problems in wood drying, and careful control of drying conditions is necessary in order to avoid this form of defects. Wood drying at different temperatures, especially high temperatures, has gained much interest in the last several decades. Some solutions for minimizing drying defects, such as cracks and decrease of mechanical properties due to the increase of drying rates, decrease of drying time and thus cost, must be acknowledged and understood. The present review tries to summarize the influence of temperature during kiln drying on the mechanical properties of wood and on the occurrence of cracks.
- Reviewpp 739-788Hubbe, M. A., Venditti, R. A., and Rojas, O. J. (2007). "What happens to cellulosic fibers during papermaking and recycling? A review," BioRes. 2(4), 739-788.AbstractPDFBoth reversible and irreversible changes take place as cellulosic fibers are manufactured into paper products one or more times. This review considers both physical and chemical changes. It is proposed that by understanding these changes one can make better use of cellulosic fibers at various stages of their life cycles, achieving a broad range of paper performance characteristics. Some of the changes that occur as a result of recycling are inherent to the fibers themselves. Other changes may result from the presence of various contaminants associated with the fibers as a result of manufacturing processes and uses. The former category includes an expected loss of swelling ability and decreased wet-flexibility, especially after kraft fibers are dried. The latter category includes effects of inks, de-inking agents, stickies, and additives used during previous cycles of papermaking.
- Reviewpp 707-738Taherzadeh, M. J., and Karimi, K. (2007). "Enzyme-based hydrolysis processes for ethanol from lignocellulosic materials: A review," BioRes. 2(4), 707-738.AbstractPDFThis article reviews developments in the technology for ethanol production from lignocellulosic materials by “enzymatic” processes. Several methods of pretreatment of lignocelluloses are discussed, where the crystalline structure of lignocelluloses is opened up, making them more accessible to the cellulase enzymes. The characteristics of these enzymes and important factors in enzymatic hydrolysis of the cellulose and hemicellulose to cellobiose, glucose, and other sugars are discussed. Different strategies are then described for enzymatic hydrolysis and fermentation, including separate enzymatic hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), non-isothermal simultaneous saccharification and fermentation (NSSF), simultaneous saccharification and co-fermentation (SSCF), and consolidated bioprocessing (CBP). Furthermore, the by-products in ethanol from lignocellulosic materials, wastewater treatment, commercial status, and energy production and integration are reviewed.
- Reviewpp 500533Hubbe, M. A., and Heitmann, J. A. (2007). "Review of factors affecting the release of water from cellulosic fibers during paper manufacture," BioRes. 2(3), 500-533.AbstractPDFThe ease with which water is released from cellulosic fiber material during the manufacturing of paper can affect both the production rate and the consumption of energy during the manufacturing process. Important theoretical contributions to dewatering phenomena have been based on flow through packed beds of uniformly distributed fibers. Such descriptions are able to explain why resistance to dewatering increases as a function of the hydrodynamic surface area of fibers. More recent studies have demonstrated a critical role of finely divided matter. If the fines are unattached to fibers, then they tend to move freely through the fiber mat and plug channels in the paper web during the dewatering process. Dewatering also is affected by the deformability of cellulosic fibers and by whether the fibers easily slide past each other, thereby forming a dense mat. By emphasizing the role of fine matter, colloidal forces, and conformability of cellulosic materials, one can gain a more realistic understanding of strategies that papermakers use to enhance initial drainage and vacuum-induced dewatering.
- Reviewpp 472-499Taherdazeh, M. J., and Karimi, K. (2007). "Acid-based hydrolysis processes for ethanol from lignocellulosic materials: A review," BioRes. 2(3), 472-499.AbstractPDFBioethanol is nowadays one of the main actors in the fuel market. It is currently produced from sugars and starchy materials, but lignocelluloses can be expected to be major feedstocks for ethanol production in the future. Two processes are being developed in parallel for conversion of lignocelluloses to ethanol, “acid-based” and “enzyme-based” processes. The current article is dedicated to review of progress in the “acid-based-hydrolysis” process. This process was used industrially in the 1940s, during wartime, but was not economically competitive afterward. However, intensive research and development on its technology during the last three decades, in addition to the expanding ethanol market, may revive the process in large scale once again. In this paper the ethanol market, the composition of lignocellulosic materials, concentrated- and dilute-acid pretreatment and hydrolysis, plug-flow, percolation, counter-current and shrinking-bed hydrolysis reactors, fermentation of hexoses and pentoses, effects of fermentation inhibitors, downstream processing, wastewater treatment, analytical methods used, and the current commercial status of the acid-based ethanol processes are reviewed.
- Reviewpp 296-331Hubbe, M. A. (2007). "Flocculation and redispersion of cellulosic fiber suspensions: A review of effects of hydrodynamic shear and polyelectrolytes," BioRes. 2(2), 296-331.AbstractPDFCellulosic fibers in aqueous suspensions are subject to flocculation effects that involve two contrasting scales of dimension. The net effect of flocculation determines how uniformly fibers can become formed into a sheet during the manufacture of paper. At a macroscopic level, the highly elongated shape of typical wood-derived fibers in agitated suspensions can give rise to frequent inter-fiber collisions and the formation of fiber flocs. At a submicroscopic scale, surfaces of suspended materials can become joined by macromolecular bridges. Although such bridges tend to reduce paper’s uniformity, polyelectrolyte flocculants are used in most paper machine systems to achieve relatively high retention efficiencies of fine particles as paper is being formed. By adjusting the papermaking equipment, judiciously selecting points of addition of chemicals, and by managing chemical dosages, papermakers employ a variety of strategies to achieve favorable combinations of retention and uniformity. This review considers scholarly work that has been directed towards a greater understanding of the underlying mechanisms.
- Reviewpp 106-145Hubbe, M. A. (2007). "Paper's resistance to wetting - A review of internal sizing chemicals and their effects," BioRes. 2(1), 106-145.AbstractPDFThis review considers research related to internal sizing agents. Such chemicals, when added as emulsions or in micellar form to slurries of cellulosic fibers before paper is made, can make the product resist water and other fluids. Significant progress has been achieved to elucidate the modes of action of alkylketene dimer (AKD), alkenylsuccinic anhydride (ASA), rosin products, and other sizing chemicals. Recent findings generally support a traditional view that efficient hydrophobation requires that the sizing chemicals contain hydrophobic groups, that they are efficiently retained on fiber surfaces during the papermaking process, that they become well distributed on a molecular scale, and that they need to be chemically anchored. A variety of studies have quantified ways in which internal sizing treatments tend to be inefficient, compared to what is theoretically possible. The inefficient nature of chemical and physical processes associated with internal sizing, as well as competing reactions and some interfering or contributing factors, help to explain apparent inconsistencies between the results of some recent studies.
- Reviewpp 281-318Hubbe, M. A. (2006). "Bonding between cellulosic fibers in the absence and presence of dry-strength agents - A review," BioRes. 1(2), 281-318.AbstractPDF
Various hydrophilic polyelectrolytes, including cationic starch products, are used by papermakers to promote inter-fiber bonding and increase paper’s dry-strength. Thus, papermakers can meet customer require-ments with a lower net cost of materials, more recycled fibers, or higher mineral content. In the absence of polymeric additives, key mechanisms governing bond development between cellulosic fibers include capillary action, three-dimensional mixing of macromolecules on facing surfaces, conformability of the materials, and hydrogen bonding. Dry-strength additives need to adsorb efficiently onto fibers, have a hydrophilic character, and have a sufficiently high molecular mass. Though it is possible to achieve significant strength gains by optimal usage of individual polyelectrolytes, greater strength gains can be achieved by sequential addition of oppositely charged polyelectrolytes. Superior strength can be achieved by in-situ formation of polyelectrolyte com-plexes, followed by deposition of those complexes onto fiber surfaces. Polyampholytes also hold promise as efficient dry-strength additives. Opportunities for further increases in performance of dry-strength agents may involve fiber surface modification, self-assembled layers, and optimization of the dry film characteristics of dry-strength polymers or systems of polymers.
- Reviewpp 270-280Hoenich, N. (2006). "Cellulose for medical applications: Past, present, and future," BioRes. 1 (2), 270-280.AbstractPDF
Films and tubes manufactured from cellulose have historically been used in the treatment of renal failure, but their use for this purpose has declined in recent years in favour of films manufactured from synthetic material blends. As the clinical application of cellulose for dialysis declines, new applications for its use are emerging, of which the most promising appears to be the use of microbial cellulose synthesized by Acetobacter xylinum as a novel wound healing system and as a scaffold for tissue regeneration.
- Reviewpp 150-171Lee, S. Y., Hubbe, M. A., and Saka, H. (2006). "Prospects for biodiesel as a byproduct of wood pulping - A review," BioRes. 1(1), 150-171AbstractPDF
Effective utilization of byproducts can affect the profitability of kraft pulping to produce cellulosic fibers from wood. This review considers opportunities to use tall oil components, obtained from kraft pulping, as a source of raw material for biodiesel fuel, or as a source of additives for petrodiesel. Considerable progress has been achieved with respect to converting vegetable oils to diesel fuel, and some of what has been learned appears to have potential application for processing of wood-derived fatty acids and related compounds. Alkaline – catalyzed trans esterification strategies, while seemingly well adapted for relatively pure vegetable oil source materials, may not be the best fit for the processing of tall oil fractions. The promising strategies to consider include acid – catalyzed esterification, enzymatic processes, hydrogenation, and the use of supercritical methanol.
- Reviewpp 93-115Moghtaderi, B., Sheng, C., and Wall, T. F. (2006). "An overview of the Australian biomass resources and utilization technologies," BioRes. 1(1), 93-115.AbstractPDF
Information on Australian biomass resources including bagasse, black liquor from paper pulp production, wood waste and forestry residues, energy crops, crop wastes, food and agricultural wet waste, and municipal solid wastes is provided in the review. The characteristics of the Australian biomass are typical of those of other countries, i.e. high moisture and volatile matter, low heating value and density, and low sulfur and nitrogen content, but high Ca and Mg for woody biomass. The characteristics influence biomass utilization. Biomass is used extensively at present within Australia , primarily for domestic heating, as bagasse in the sugar industry, and for electricity generation. Biomass usage for electricity generation is increasing and is expected to reach 5.2 Mt/year by 2019-20. Exports, as wood chips, are approximately 10 Mt/year in 2000-01. Forestry residues have been estimated to be 23 Mt/year. Current technologies that utilize biomass in Australia include those for electricity and heat by direct combustion, cofiring with coal and fluidized bed combustion), for biogas generation (from landfills, and aerobic digestion, and as bio-liquids. Related to bio-liquid fuels, ethanol production from molasses and wheat is making progress. The resultant ethanol is used as a petrol extender, and a bio-diesel process is under development.
- Reviewpp 116-149Hubbe, M. A. (2006). "Sensing the electrokinetic potential of cellulosic fiber surfaces," BioRes. 1(1), 116-149.AbstractPDF
The charged nature of a cellulosic fiber surface is expected to play major roles in such phenomena as fiber dispersion, flocculation, adhesion, and adsorption of polyelectrolytes. This review focuses on the evaluation of such charges by means of electrokinetic measurements, with emphasis on the fiber-pad streaming potential technique. Results of recent experiments suggest that a continuous network or networks of pores below the outer surface of a kraft fiber can significantly contribute to observed streaming potential data. At present it is not clear whether the main subsurface contributions to the observed electrokinetic effects come from fibrillar layers on the fiber surfaces or from systems of nanopores within the cell walls of fibers. Based on the literature it is possible to suggest two conceptual models to account for the fact that the streaming potential of polymer-treated fibers can change in sign, dependent on the concentration of salt. Additional research is needed to clarify various theoretical and practical points. There may be oppor-tunities to make more effective use of streaming potential tests in the future by carrying out such tests at reduced salt levels.