Volume 13 Issue 2

Wood is our material of choice for sustainable and environmental friendly construction and manufacturing of products. Wood has excellent properties for reuse, realized and implemented through a cascading utilization, introducing intermittent product lives. In contrast, wood waste is still a heavily under-valued resource in North America. With current practices of sourcing virgin wood at lowest cost and few efforts to shift wood out of the single-use convenience mode of utilization, true innovation is unlikely to occur. Technical problems have been assessed and solved. What remains is collecting and combining unintelligently scattered and hidden information about wood utilization into a single place. And, if connecting a complimentary feedstock supply to our current industries remains a challenge, then innovation must happen on the product-side too.

The wet strength of paper is an important physical property, especially for household paper, e.g., paper towels, as well as for some functional paper grades. However, in the literature, various conditions of immersing the samples in water before testing have been reported, resulting in differences in their extent of saturation and inconsistency in the testing results. Also, the dryness of paper specimens before the wet-strength testing is a critical parameter for the wet strength of paper; however, this aspect has been neglected in the literature. In this editorial, the methods of examination for both the temporary and permanent wet strength are discussed. A more reasonable method is proposed, such that the wet strength is reported according to the immersion time and the initial dryness of the paper. As an option, the results may be expressed as a function of immersion time and initial dryness. In this way, the trend of temporary wet strength related to the immersion time in water can be expressed clearly and the permanent wet strength also can be evaluated comprehensively.

Lactic acid is an important organic compound that finds various applications in the chemical, pharmaceutical, food, and medical industries. Many of these applications require lactic acid with high purity. Hybrid short path evaporation (HSPE) is a separation process well studied in the petrochemical sector that is mainly used to obtain compounds with high purity. It is also a process offering small residence time, low pressure, and environmentally friendliness. The concentration process of lactic acid was studied by using HSPE in the presence of high total reducing sugar content remaining from sugarcane molasses fermentation. In this work, the influence of operational conditions, such as evaporator temperature (86.4 °C to 153.6 °C), internal condenser temperature (7.95 °C to 18 °C), and feed flow rate (8.27 to 21.7 mL/min), on lactic acid concentration and mass percentages were evaluated. The results showed that all variables influenced the process. Mathematical models were developed for the mass percentage and concentration of the total reducing sugar in the distilled stream and for the mass percentage at residue stream. Under the best operational conditions, the concentration of lactic acid (≈ 247.7 g/L) was 2.5 times higher than the initial fermentation broth (≈ 100.1 g/L).

A continuous screw extrusion steam explosion (SESE) pretreatment method was used to disrupt the structure of eucalyptus fiber. The effects of increasing numbers of SESE pretreatment cycles on the structure and composition of eucalyptus fiber were investigated. Lignin was isolated from the eucalyptus fiber via the phosphoric acid method under modest reaction conditions (50 °C), and was characterized. The SESE pretreatment led to a decrease in crystallinity and degraded the hemicellulose and cellulose. The surface of the eucalyptus fiber was damaged by SESE pretreatment, and significant surface debris were observed. The isolated lignin was typical of guaiacyl-syringyl (G-S)-enriched lignin of eucalyptus hardwood. The SESE pretreatment led to the cleavage of ether linkages and condensation of lignin, and thus a more heterogeneous structure compared with that of raw lignin. The increased molecular weight of SESE-pretreated lignin showed that condensation was more pronounced with increased numbers of SESE cycles. The thermostability of lignin increased after three SESE cycles and remained stable with further cycles. This corresponded to the trend in the molecular weight of lignin with increased SESE pretreatment. The SESE pretreatment was more efficient for pretreating eucalyptus fiber than conventional batch-type steam explosion, and thus is more suitable for industrial application.

Wood-based panels, which are often used and then abandoned, are a potential resource for energy recovery. To better understand the pyrolysis of wood-based panels, the effect of urea formaldehyde (UF) resin on the pyrolysis of the wood components (cellulose, hemicellulose, and lignin) was investigated. Thermogravimetric analysis (TGA), gas chromatography coupled with mass spectrometry (GC-MS), and an ultimate analysis were used to investigate the pyrolysis process and products of the biomass components mixed with 10% UF resin. The UF resin specifically inhibited the decomposition rate of cellulose and promoted the thermal decomposition of lignin. For xylan, the UF resin had little impact. The UF resin mainly affected the mass loss of C and O. Loss of both elements in lignin was promoted, but only C loss increased in cellulose. The nitric gases generated from the pyrolysis mixtures were HCN and NH3, and N from the UF resin tended to transform into NH3. Influence of the UF resin on the pyrolysis liquids was mainly seen on the N compounds. With the addition of the UF resin, more nitrogenous compounds were detected in the pyrolysis liquids. The relative contents of nitrogenous compounds in the pyrolysis liquids from cellulose and lignin were 12.8% and 64.3%, respectively.

Three strains of bacteria were isolated and purified from activated sludge for white water treatment in the laboratory. These strains were identified as Bacillus subtilis, Bacillus cereus, and Virgibacillus pantothenticus through a morphological analysis, the MIDI Sherlock automatic microbial identification system, and 16S rRNA methods. The results of the construction of efficient microflora for white water showed that a mass percentage ratio of B. subtilis, B. cereus, and V. pantothenticus of 50%:35%:15% achieved an optimal treatment effect. Analysis by gas chromatograph-mass spectrometer (GC-MS) established that the content of characteristic pollutants in white water decreased notably after treatment with the efficient microflora, and detected the intermediate products of short chain fatty acids, alcohols, and other compounds. Moreover, through measuring the removal rate of chemical oxygen demand (COD), electrical conductivity, and cationic demand (CD), the optimal retention time for white water treatment with the efficient microflora was 4 h to 6 h, and when the removal rate of COD reached approximately 90%, the electrical conductivity and the cationic demand were reduced to lower values.

The aim of this study was to reach the best efficiency of total polyphenols extraction from beech bark. The impacts of solvent concentration, sonication time, and temperature were investigated relative to the yield of extractives from beech (Fagus sylvatica L.) bark using ultrasound-assisted extraction at 40 kHz ultrasonic frequency. All extracts were characterized quantitatively in terms of total content in polyphenols. The extracts obtained in the optimized conditions were also evaluated qualitatively. Beech bark can be a rich raw material for obtaining bioactive polyphenols. An experimental planning method was described that optimized the process and increased the extraction yield. In the experiments, water and ethanol:water solvent solutions were used. The efficiency of the extraction process was determined based on a factorial analysis of variance. The maximum extraction yield of total polyphenols (72.716 mg gallic acid equivalents/g beech bark) was obtained using a processing time of 20 min, an extraction temperature of 65 °C, and an ethanol solvent concentration of 70%. The extracts obtained under the optimum conditions were characterized to determine potential uses of beech bark extractives. The results obtained indicated that ultrasound-assisted extraction was an efficient method for the extraction of natural compounds from beech bark; thus, this method allows for the full utilization of this abundant and low-cost industrial waste.

The thermo-hygromechanical densification process changes the chemical composition and the physical and mechanical properties of wood. The aim of this work was to study the impact of the chemical composition of Pinus radiata wood on its physical and mechanical properties following the thermo-hygromechanical densification process. The samples were initially segregated by lignin content. Density, hardness, modulus of elasticity (MOE), and modulus of rupture (MOR), in addition to lignin, α-cellulose, hemicellulose, and extractive contents, were determined before and after the densification process. The results indicated that densified wood with high initial lignin content had greater rate of increases in density and MOE than wood with lower initial lignin content. Additionally, densified wood with lower initial lignin content had greater rate of increases in hardness. The rate of increase of MOR did not show significant differences within both groups. Carbohydrates present in the control and the densified wood played an important role in the mechanical strength of the final product.

Nanocellulose is a competitive reinforcement material for use in biocomposite structures and fibrous products. In this study, adhesive mixtures of dicarboxylic acid cellulose nanofibrils (CNF) were dispersed into commercial polyvinyl acetate (PVAc) and starch adhesives, which were applied to Norway spruce (Picea abies) to assess their performance in wood joining. Single-lap joints were prepared and tested with PVAc mixtures with 0 to 0.64 wt% CNF and starch glue mixtures containing 0 to 1.07 wt% CNF. CNF suspensions having three concentrations (0.64, 0.96, and 1.28%) were compared. The results showed that the optimum amount of CNF, 0.48% suspensions, added to PVAc increased the average lap joint strength (EN 205:2003) by 74.5% when compared to control specimens with pure PVAc. Correspondingly, 0.96% CNF suspensions also enhanced the strength of starch adhesive by 34.5%. Lower and higher CNF concentrations showed clearly inferior performance.

This study examined a novel approach for converting waste water hyacinths into high-value chemicals under low temperature and low atmospheric pressure by using iron (III) chloride (FeCl3), an oxidant that has the unique properties of nontoxicity, low-cost, and abundance. The conversion process and transformation products of water hyacinths under different conditions were investigated and characterized. The results showed that the content of lignocellulose gradually decreased in the reaction solution. The chemical structure of lignocellulose in the water hyacinths was changed, and the glycosidic bonds of the water hyacinths were cleaved. The surface structure and crystalline regions of the water hyacinths were also damaged during the reaction. Furthermore, the hemicellulose and cellulose in the water hyacinths were dissolved and hydrolyzed to reducing sugars in the reaction solution, and then the reducing sugars were further dehydrated to hydroxymethylfurfural (HMF) and furfural. Lignin in the water hyacinths was depolymerized into aromatic and hydrocarbon compounds. The process presented in this study effectively alleviates environmental pollution by efficient utilization of aquatic wastes, and it produces high-value chemicals from biomass waste.