Volume 3 Issue 1
Yu, H., Du, C., Liu, H., Wei, J., Zhou, Z., Huang, Q., and Yao, X. (2017). "Preparation and characterization of bamboo strips impregnation treated by silver-loaded thermo-sensitive nanogels," BioRes. 12(4), 8390-8401.Louhelainen, J., Lehto, J., Kłosińska, T., Drożdżek, M., and Alén, R. (2017). "Characterization of pre-treatments on wood chips prior to delignification by near infrared spectroscopy," BioRes. 12(4), 8378-8389.View our current issue
- There exists a direct correlation between improvements in standard of living and the consumption of resources. To be able to maintain the standard of living of a modern developed country, society must adapt to an economy based on sustainable processes, energy, and raw materials. The sustainable economy presents itself as a disruptive technology to the traditional economy, which is based largely on non-renewable resources. The issue seems to be more about when will we switch to a sustainable economy, rather than whether we will switch.
- Researchpp 3-12Wang, H., Li, B., and Shi, B. (2008). "Preparation and surface acid-base properties of porous cellulose," BioRes. 3(1), 3-12.AbstractPDFPorous cellulose beads were prepared by solubilizing cellulose in sodium hydroxide/urea/sulfourea aqueous solution and then solidifying liquid beads in hydrochloric acid. Scanning electron microscopy (SEM) was used to characterize the morphologies of surface, cross section, and wall structures of the porous cellulose beads, which are folded and porous. The surface acid-base properties of porous cellulose beads were characterized in detail by inverse gas chromatography (IGC). The Lewis basic number Kb was found to be 0.854, which is indicative of a Lewis basic polymeric material. With the discussion of the results of SEM and IGC, a conclusion can be drawn that the porous cellulose beads showed a good ability of adsorbing the smoking tar of cigarettes.
- Researchpp 13-20Malutan, T., Nicu, R., and Popa, V. I. (2008). "Contribution to the study of hydroxymethylation reaction of alkali lignin," BioRes. 3(1), 13-20.AbstractPDFThe hydroxymethylation of alkali lignin with formaldehyde in alkaline solution was studied. The influence of reaction conditions of the hydroxymethylation of alkali lignin was followed by modifying the temperature, time, and the ratios of NaOH to lignin and CH2O to lignin. Three different types of alkali lignin were utilized. The reaction was followed by total consumption of formaldehyde, and the resulting products were characterized through FTIR-spectra, thermogravimetry analysis, ash and moisture contents, as well as by the amounts of OH groups.
- Researchpp 21-33Zoia, L., Canevali, C., Orlandi, M., Tolppa, E.-L., Sipila, J., and Morazzoni, F. (2008). "Radical formation on TMP fibers and related lignin chemical changes," BioRes. 3(1), 21-33.AbstractPDFOxidation of TMP fibers was compared at 298 K with molecular oxygen, in the presence of either [Co(salen)] in methanol or [Co(sulphosalen)] in water. Electron paramagnetic resonance (EPR) spectroscopy made it possible to reveal and quantify the formation of phenoxy cobalt radicals in the former case and of phenoxy radicals in the latter. These radicals reached the same concentration after 60 min from the onset of reaction. Fiber integrity was more preserved after oxidation in water than in methanol, as assessed by heteronuclear single quantum coherence - nuclear magnetic resonance (2D-HSQC-NMR) spectroscopy, nuclear magnetic resonance spectroscopy of carbon (13C-NMR), and Gel Permeation Chromatography (GPC). These results suggest that efficient radical formation on fibers can be achieved also with water-soluble catalysts. Thus, it is proposed that treatment with molecular oxygen in the presence of [Co(sulphosalen)] in water represents a promising way to approach an environmentally sustainable radicalization of fibers, without heavy modification of the lignin structure.
- Researchpp 34-45Kontturi, E., Mitikka-Eklund, M., and Vuorinen, T. (2008). "Strength enhancement of a fiber network by carboxymethyl cellulose during oxygen delignification of kraft pulp," BioRes. 3(1), 34-45.AbstractPDFSorption of carboxymethyl cellulose (CMC) on the fiber surface was applied during oxygen delignification to enhance the strength properties of softwood kraft pulp. Unlike many previous efforts, the focus was not set on the improvement of selectivity of oxygen delignification, i.e. retaining stable viscosity vs. decreasing kappa number. Instead, without an improved selectivity, handsheets from CMC-treated fibers exhibited a 15% improvement in tensile index and 25% improvement in tear index after a full bleaching sequence in comparison to the untreated reference pulp. Since it is demonstrated that the CMC addition can be incorporated as an integral step in the fiberline process, the method offers an effortless and viable option to produce pulp resulting in stronger paper products.
- Researchpp 46-59Nada, A.-A. M. A., Alkady, M. Y., and Fekry, H. M. (2008). "Synthesis and characterization of grafted cellulose for use in water and metal ions sorption," BioRes. 3(1), 46-59.AbstractPDFGraft copolymerization of acrylamide monomer onto cellulose, using ceric ammonium nitrate as initiator, was investigated. Water and metal ions sorption by this grafted cellulose were estimated. The conditions of grafting, e.g. grafting time, dose of initiator, ratio of monomer to cellulose, acid concentration and liquor ratio, were evaluated. The different properties as graft and graft efficiency percentage, as well as polymerization percent, have been determined. Grafted cellulose has been characterized by FTIR and swelling studies. Sorption of different metal ions in the mixture, e.g. Cu, Cr, Ni, and Pb, by grafted cellulose was investigated. The effect of hydrolysis of grafted cellulose by using sodium hydroxide on its swelling properties and metal ions sorption was also investigated. Hydrolysis increases the sorption affinity of grafted cellulose toward water and metal ions .
- Researchpp 60-70Ebringerová, A., Hromádková, Z., Košťálová, Z., and Sasinková, V. (2008). "Chemical valorization of agricultural by-products: Isolation and characterization of xylan-based antioxidants from almond shell biomass," BioRes. 3(1), 60-70.AbstractPDFThe isolation of non-cellulosic polysaccharides from almond shells (AS) and their solid residue (ASR) after autohydrolysis was investigated using a two-step alkaline extraction without and in combination with short ultrasonic treatment. The obtained polysaccharide preparations were characterized by yield, chemical composition, and structural features, and the antioxidant activity of the water-soluble preparations tested. The results showed that the use of ultrasound at a reduced extraction time of 10 min as compared to 60 min of the classical procedure, with a 5% NaOH solution, resulted in the greatest yield of hemicelluloses. The AOA of their water-soluble portion ranged between 48 and 80%, indicating the antioxidant potential of these materials. The xylan polymers isolated from both AS and ASR might serve as biopolymer sources in native form or after targeted modification for production of value-added substances and polysaccharide-based antioxidants applicable in food, cosmetics, and other areas.
- Researchpp 71-78Hromádková, Z., Malovíková, A., Mozeš, Š., Sroková, I., and Ebringerová, A. (2008). "Hydrophobically modified pectates as novel functional polymers in food and non-food applications," BioRes. 3(1), 71-78.AbstractPDFButyl and hexyl amides of pectate with various amidation degrees were prepared from citrus pectin by means of alkylamidation of methyl-esterified pectins, followed by the total alkaline pectin methyl esters hydrolysis. These water soluble derivatives were characterized chem-ically as well as by elementary analysis and FT-IR spectroscopy. All prepared pectate amides exhibited the excellent emulsifying efficiency, and pectate hexyl amide also the ability to form stable foam. As the results of the study on the effect of pectin with DE 66% on the function of small intestine in pectin fed rats, the increase of specific activity of alkaline phosphatase, maltase, and aminopeptidase and the decrease of food utilization was demonstrated. The pectin derivatives might serve as emulsifiers and foaming additives in food production and other areas as well as nutraceuticals for obesity treatment.
- Researchpp 79-90Heinze, T., Pfeifer, A., and Petzold, K. (2008). "Functionalization pattern of tert-butyldimethyl-silyl cellulose evaluated by NMR spectroscopy," BioRes. 3(1), 79-90.AbstractPDFTert-butyldimethylsilyl cellulose with a degree of substitution (DS) of up to 2 could be obtained by homogeneous conversion of the biopolymer with tert-butyldimethylchlorosilane in N,N-dimethyl acetamide/LiCl in the presence of imidazole. The cellulose derivatives were characterized in detail by means of two-dimensional NMR spectroscopic techniques including subsequent derivatization of the original polymer by consecu-tive methylation-desilyation-acetylation. The very well resolved NMR spectra indicate that, dependent on the reaction temperature, 2,6-di-O-tert-butyldimethylsilyl moieties are the main repeating units. 3,6-di-O- and 6-mono-O functionalized repeating units were identified in very small amounts if the reaction is carried out at room temperature. Additionally, 2,3,6-tri-O-silylated functions appear if reaction is carried out at temperature of 100°C. Thus, a novel path for regioselective protection of position 2 and 6 for cellulose was established.
- Researchpp 91-97Csóka, L., Lorincz, A., and Winkler, A. (2008). "Sonochemically modified wheat straw for pulp and papermaking to increase its economical performance and reduce environmental issues," BioRes. 3(1), 91-97.AbstractPDFWheat straw (an agricultural by-product) was pulped by an alkaline anthraquinone (AQ) process. Then the straw pulp was treated by high-power ultrasound under different noble-gas (argon, krypton, xenon) combinations. The pulps’ degree of beating and acid-insoluble lignin content were measured. Handsheets were made from sonicated and control pulps and tested for paper tensile strength. In this study we explore which noble-gas combination with ultrasound may be more useable to reduce the lignin content and enhance fibrillation. We also describe the most effective ultrasound-assisted, modified alkaline pulping process. Overall, we found that in two steps ultrasonification decreased the residual lignin contents more then 75 %, the pulp fibrillation increased from 12 to 70 °SR within 20 min. of ultrasound irradiation, and the tensile index of the handsheets increased by 65%. For sustainable paper production, it is required to develop alternative paper resources. Paper made from alternate fiber resources with efficient technology will improve our living standards without sacrificing the environment, our habitat. High frequency ultrasound-based pulp processing offers significant improvements, and it reduces energy and chemical consumptions for pulp and paper production.
- Researchpp 98-107Galgut, P. N. (2008). "Radiographic observations on the use of two different regeneration materials in a single subject: Case study," BioRes. 3(1), 98-107.AbstractPDFTwo infrabony defects (i.e. defects in tooth supporting bone that extend into the body of the bone) in different sites in the same individual were treated surgically. Tissue regeneration was incorporated into the surg-ical procedures using a different material in each site (oxidized cellulose mesh and bioglass). The post surgical radiographic appearance showed increasing calcification in both sites that was not complete even at 15 months after placement. The radiographic appearance of both sites was similar but calcification was observed above the crest of alveolar bone in the oxidized cellulose mesh site that was not present with bioglass site. As calcification did not appear to be complete by 15 months after place-ment and it did not resemble true bone in either site, it would appear that the regenerative process was not yet complete by this time. Bone regeneration may therefore progress slowly over a protracted period of time after placement. Some evidence is present that oxidized cellulose mesh may have enhanced regenerative capacity by comparison to other synthetic bone regeneration materials such as hydroxyapatite and bioglass. No conclusions could be drawn from this single case study and further work is necessary to confirm and investigate these observations more fully.
- Researchpp 108-122Talebnia, F., Pourbafrani, M., Lundin, M., and Taherzadeh, M. J. (2008). "Optimization study of citrus wastes saccharification by dilute-acid hydrolysis," BioRes. 3(1), 108-122.AbstractPDFThe effects of time, acid concentration, temperature and solid concentra-tion on dilute-acid hydrolysis of orange peels were investigated. A central composite rotatable experimental design (CCRD) was applied to study the individual effects of these hydrolysis factors and also their inter-dependence effects. The enzymatic hydrolysis of the peels by cellulase, β-glucosidase, and pectinase enzymes resulted in 72% dissolution of the peels, including 18.7% galacturonic acid and 53.3% of a total of glucose, fructose, galactose, and arabinose. Dilute-acid hydrolysis up to 210°C was not able to hydrolyze pectin to galacturonic acid. However, the sugar polymers were hydrolyzed at relatively low temperature. The optimum results were obtained at 116°C, 0.5% sulfuric acid concentration, 6% solid fraction, and 12.9 min retention time. Under these conditions, the total sugars obtained at 41.8% dry peels and 2.6% of total hexose sugars were further degraded to hydroxymethylfurfural (HMF). No furfural was detected through these experiments from decomposition of pentoses.
- Researchpp 123-141Montoneri, E., Boffa, V., Quagliotto, P., Mendichi, R., Chierotti, M. R., Gobetto, R., and Medana, C. (2008). "Humic acid-like matter isolated from green urban wastes. Part 1. Structure and surfactant properties," BioRes. 3(1), 123-141.AbstractPDFA humic acid-like substance (cHAL2) isolated from urban green wastes before composting was compared to a humic acid-like substance (cHAL) isolated from a mix of urban organic humid waste fraction and green residues composted for 15 days. cHAL2 was found to contain more aliphatic and O-alkyl C atoms relative to aromatic, phenol, and carboxyl C atoms, and to yield higher critical micellar concentration (cmc = 0.97 g L-1) and surface tension at the cmc (gcmc = 37.8 mN/m) in water than cHAL (cmc = 0.40 g L-1; gcmc = 36.1 mN/m). The results point out that biomass wastes may be an interesting source of biosurfactants with diversified properties that depend on the nature of waste and on its process of treatment.
- Researchpp 142-154Esteves, B. M., Domingos, I. J., and Pereira, H. M. (2008). "Pine wood modification by heat treatment in air," BioRes. 3(1), 142-154.AbstractPDFMaritime pine (Pinus pinaster) wood has low dimensional stability and durability. Heat treatment was made in an oven using hot air during 2 to 24 h and at 170-200 ºC. A comparison was made against steam heat treatment. The equilibrium moisture content and the dimensional stability (ASE) in radial and tangential directions were evaluated at 35%, 65%, and 85% relative humidity. MOE, bending strength and wettability were also determined. At the same mass loss, improvements of equilibrium moisture content and dimensional stability were higher for oven heat treatment, but the same was true for mechanical strength degradation. A 50% decrease in hemicellulose content led to a similar decrease in bending strength.
- Researchpp 155-169Foulk, J. A., Akin, D. E., and Dodd, R. B. (2008). "Influence of pectinolytic enzymes on retting effectiveness and resultant fiber properties," BioRes. 3(1), 155-169.AbstractPDFEnzymes have the potential to provide an improved method to ret flax for textile fibers. Retting is the separation or loosening of fiber bundles from the cuticularized epidermis and the woody core cells. New commercial pectinase products were evaluated both with and without ethylene-diaminetetraacetic acid (EDTA) for retting efficiency. The Fried Test identified the most efficient enzymes and best retting conditions. All enzymes retted flax stems better in the presence of 18 mM EDTA. Pectinases that also contained cellulases reduced fiber strength, whereas those without cellulases effectively retted flax without substan-tial strength loss. Viscozyme, which has been used extensively in our enzyme-retting research, and several pectinolytic enzymes were compared in pilot plant scale tests. Texazym BFE and Bioprep 3000 L retted flax as well as Viscozyme in this system, and the fibers had higher tenacity. The monocomponent nature, commercial availability and price, and ability to ret flax in combination with EDTA at high pH indicated a potential advantage for Bioprep 3000 L in these tests. Retting with different enzymes and formulations resulted in fibers with different properties, thereby leading to protocols for tailored fiber characteristics.
- Researchpp 170-177Ioelovich, M., and Leykin, A. (2008). "Structural investigations of various cotton fibers and cotton celluloses," BioRes. 3(1), 170-177.AbstractPDFMacro- and crystalline structure, as well as chemical composition of fibers related to various types and sorts of Israeli cottons, both white and naturally colored, were investigated. The differences in structural parameters and chemical compositions of the cotton fibers were eval-uated. Samples of cotton of the “Pima”-type had long, thin and strong fibers with highly ordered supermolecular structure. Fibers of middle-long and hybrid cottons had some lower-ordered structural organization in comparison to long-length cotton, while fibers of naturally colored cotton were characterized with disordered supermolecular and crystalline structure. Dependence of tensile strength on orientation of nano-fibrils towards the fiber axis was found. Conditions of cellulose isolation from the different cotton fibers were studied. Structural characteristics of isolated cotton celluloses and obtained MCC are discussed.
- Researchpp 178-191Mikkonen, K. S., Yadav, M. P., Cooke, P., Willför, S., Hicks, K. B., and Tenkanen, M. (2008). "Films from spruce galactogluccomannan blended with poly(vinyl alcohol), corn arabonoxylan, and konjac glucomannan," BioRes. 3(1), 178-191.AbstractPDFThe improvement of mechanical properties of spruce galactogluco-mannan (GGM)-based films was sought by blending GGM with each of poly(vinyl alcohol) (PVOH), corn arabinoxylan (cAX), and konjac glucomannan (KGM). The blend ratios were 3:1, 1:1, and 1:3 (w/w), and in addition films were made from each of the polymers alone. Glycerol was used as plasticizer. Adding other polymers increased the elongation at break of GGM blend films. The tensile strength of films increased with increasing amount of PVOH and KGM, but the effect of cAX was the opposite. Dynamic mechanical analysis showed two separate loss modulus peaks for blends of GGM and PVOH, but a single peak for all other films. Optical and scanning electron microscopy confirmed good miscibility of GGM with cAX and KGM. In contrast, films blended from GGM and PVOH showed phase separation when examined by microscopy.
- Researchpp 192-203Subramanian, R., Kononov, A., Kang, T., Paltakari, J., and Paulapuro, H. (2008). "Structure and properties of some natural cellulosic fibrils," BioRes. 3(1), 192-203.AbstractPDFThis study examines the properties of cellulosic fibrillar fines manufactured from different pulp raw materials, bleached softwood kraft (BSWK), thermomechanical pulp (TMP), and non-wood sisal. Chemical characterisation showed that the carbohydrate and lignin contents of sisal were between those of BSWK and TMP. Sisal was found to contain about three times more calcium than showed that the solids content after immobilization was highest for the sisal suspension, followed by TMP and BSWK. This indicates that the dewatering ability of the fines suspension increased in the order BSWK, TMP and sisal. The loss modulus (G'') was maxmium with BSWK, indicating that the greatest viscous dissipation before immobilisation took place in the BSWK suspension. The strength properties of fines sheets decreased in the order BSWK, TMP and sisal. This is due to the highly fibrillated nature of BSWK fines, as illustrated by fibre saturation point (FSP), differential scanning calorimetric (DSC), and hydrodynamic specific volume (HSV) measurements.
- Researchpp 204-216McSweeny, J. D., Rowell, R. M., Chen, G. C., Eberhardt, T. L., and Min, S.-H. (2008). "Periodate and hypobromite modification of Southern Pine wood to improve sorption of copper ion," BioRes. 3(1), 204-216.AbstractPDFMilled southern pine wood was modified with sequential treatments of sodium periodate and sodium hypobromite for the purpose of improving copper ion (Cu2+) sorption capacity of the wood when tested in 24-h equilibrium batch tests. The modified wood provided additional carboxyl groups to those in the native wood and substantially increased Cu2+ uptake over that of unmodified wood. Sorption capacity (qe) measured with an unbuffered standard solution increased to a maximum of 7.8 mg Cu2+ ion per gram of wood (treated) from 3.1 mg Cu2+ ion/g wood (untreated). Samples tested were first sodium ion exchanged to keep the pH of the standard solution from declining during the sorption test. The treatment necessary for maximum qe was 3% (w/v) periodate for 24 h and 0.8% (w/v) bromine (as hypobromite) for 24 h; both treatments were at room temperature. These conditions corresponded to the maximum periodate concentration and treatment times tested. To further evaluate the efficacy of modification treatments, weight change after each treatment was determined. Weight loss after the periodate stage for any concentration and time used was minor, indicating the selective nature of this reaction. However, most of the weight loss was incurred after hypobromite treatment. Weight loss corresponding to the greatest increase in sorption capacity was 12.6% total from the combined periodate and hypobromite stages. The increase of carboxylate functional groups in the wood was monitored using FTIR/ATR spectroscopy.
- Researchpp 217-233Montoneri, E., Savarino, P., Bottigliengo, S., Musso, G., Boffa, V., Prevot, A. B., Fabri, D., and Pramauro, E. (2008). "Humic acid-like matter isolated from green urban wastes. Part II: Performance in chemical and environmental technologies," BioRes. 3(1), 217-233.AbstractPDFMilled southern pine wood was modified with sequential treatments of sodium periodate and sodium hypobromite for the purpose of improving copper ion (Cu2+) sorption capacity of the wood when tested in 24-h equilibrium batch tests. The modified wood provided additional carboxyl groups to those in the native wood and substantially increased Cu2+ uptake over that of unmodified wood. Sorption capacity (qe) measured with an unbuffered standard solution increased to a maximum of 7.8 mg Cu2+ ion per gram of wood (treated) from 3.1 mg Cu2+ ion/g wood (untreated). Samples tested were first sodium ion exchanged to keep the pH of the standard solution from declining during the sorption test. The treatment necessary for maximum qe was 3% (w/v) periodate for 24 h and 0.8% (w/v) bromine (as hypobromite) for 24 h; both treatments were at room temperature. These conditions corresponded to the maximum periodate concentration and treatment times tested. To further evaluate the efficacy of modification treatments, weight change after each treatment was determined. Weight loss after the periodate stage for any concentration and time used was minor, indicating the selective nature of this reaction. However, most of the weight loss was incurred after hypobromite treatment. Weight loss corresponding to the greatest increase in sorption capacity was 12.6% total from the combined periodate and hypobromite stages. The increase of carboxylate functional groups in the wood was monitored using FTIR/ATR spectroscopy.
- Researchpp 234-246Soni, R., Nazir, A., Chadha, B. S., and Saini, H. S. (2008). "Novel sources of fungal cellulases for efficient deinking of composite paper waste," BioRes. 3(1), 234-246.AbstractPDFTwenty thermophilic/thermotolerant fungal strains were isolated from compositing soils and screened for production of different enzymes (Endoglucanases, β-glucosidase, Fpase and xylanases) to assess their deinking efficiency. Three isolates, Aspergillus sp. AMA, Aspergillus terreus AN1,and Myceliophthora fergusii T4I, identified on the basis of morphological and sequencing of amplified ITS1-5.8S-ITS2 rDNA region, showed significant deinking of composite waste paper (70% magazine and 30% Xerox copier/ laser print paper waste) as well as improved properties (brightness, tensile strength, tear index) of recycled paper sheets. The chosen strains Aspergillus sp. AMA, Aspergillus terreus AN1and Myceliophthora fergusii T4I, showed 53, 52.7, and 40.32% deinking with increase in brightness by 4.32, 3.56, and 3.01 % ISO, respectively. These cultures were found to produce multiple endoglucanases and were characterized to lack a cellulose binding module (CBD), which may be responsible for their better deinking efficiency.
- Researchpp 247-254Chen, Y., Liu, Y.-F., and Tan, H.-M. (2008). "Preparation of macroporous cellulose-based superabsorbent polymer through the precipitation method," BioRes. 3(1), 247-254.AbstractPDFSuperabsorbent polymer was prepared by graft polymerization of acrylic acid onto the chain of carboxymethyl cellulose. This superabsorbent polymer was further treated by the solvent precipitation method. We found that the water absorption rate of the treated polymer was greatly increased and the microstructure of the treated polymer was changed from close-grained structures to loose macropores. The swelling processes of the polymers before and after modification fit first-order dynamic processes. The amount of the residual acrylic acid was detected through high performance liquid chromatography (HPLC) with aqueous solution of MOPS of 0.02mol/L (pH=5.70) as the mobile phase. It was found that the amount of the residual acrylic acid decreased from 83.8×10-4 % to 6.7×10-4 % after treatments.
- 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 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.