Volume 15 Issue 2

An oxygen-enhanced organosolv fractionation method to produce lignin from waste biomass was investigated. In this novel biorefinery process, mild conditions, i.e., temperature at 80 to 100 °C and pressure < 0.8 MPa, were employed to alleviate energy input and to retain the original lignin structure as much as possible. The results showed that the lignin yield was increased with increasing process temperature, ethanol concentration, and ratio of liquid to solid. Although little structural changes were observed, the normalized Infrared transmittance results revealed quantitative differences. Moreover, a basic kinetic study was conducted, and the results showed that there existed two stages with fast and slow rates during the delignification processes. Analysis of the fibers’ micro-structure also demonstrated the effectiveness of oxygen-enhanced organosolv fractionation. However, a phenol-based inducer could possibly further improve the efficiency based on the delignification mechanism of reactive oxygen species, which will be studied in future research.

The inhibitory ability of Fokienia hodginsii heartwood (FHH) extracts on Trametes versicolor (TV) and Gloeophyllum trabeum (GT) as well as the toxic effect of its heartwood extracts on GT were studied. The growth inhibition ability of the samples was analyzed using the growth rate method. The results showed that in the experiment of inhibiting TV, extracts using hot water had little effect, acetone extracts had the best inhibiting effect, and the lowest value of acetone EC50 was 0.409 g/L. The parameter EC50 is the concentration of the corresponding agent that inhibits the growth of 50% fungi. In the antifungal experiment of GT, methanol extract had the best inhibition effect, and the lowest EC50 value was 0.283 g/L. The antifungal effect of five solvent extracts of FHH was good when the concentration was 10% (w/w), and at this time, the mass loss rate of the test pieces was below 11%, all of them were Class I, indicating a strong antifungal level. After observing the samples of GT with SEM, it was found that the structure of methanol extract treatment was more complete and the antiseptic effect was better than that of the hot water extract treatment.

The efficacy of chitosan oligomers and related nanoparticles as environmentally friendly wood protection agents was evaluated in this study. Commercially sourced low-molecular weight chitosan was depolymerized using sodium nitrite. Evaluation of depolymerized chitosan to the nano level by thin layer chromatography confirmed acceptable results for obtaining a degree of polymerization of four. Then, oligomers were modified to form quaternized chitosan oligomers. Both quaternized and non-quaternized oligomers were mixed with tripolyphosphate (TPP) to form nano-chitosan-TPP particles via an ionic gelation method. Southern pine wood samples were treated with different chitosan-based solutions and suspensions under a vacuum impregnation process. The mass and volume of the treated samples were calculated before and after treatments to evaluate bulking. The mass loss after leaching of the treated wood samples was calculated. The mass and volume gain results indicated that quaternized nano-chitosan-TPP treated samples had more mass and volume gain after treatment in comparison with non-quaternized nano-chitosan-TPP-treated and control samples. The mass loss results revealed that mass loss increased in quaternized nano-chitosan-TPP particles. Although quaternized nano-chitosan particles were positively charged, they could not fix to the cell walls and became leached out. Therefore, these nanoparticles can likely be used as wood preservatives in non-leaching applications.

This study was performed to acquire key market and raw material usage information for the wood pallet and container industry in 2016. Historical trends in the wood pallet market were also analyzed between 1991 and 2016 using the results of previous Virginia Tech pallet surveys sponsored by NWPCA and U.S. Forest Service. The wooden pallet and container industry produced an estimated 513 million new wood pallets in 2016, which is a 23% increase since 2011. Approximately 35% of this was 48” x 40” pallets, which continues to be the dominant standardized pallet size. Approximately 39% of new wood pallets were custom sizes, which is a significant decrease from the 60% share found in 2011. Stringer class pallets remained the dominant pallet class with 76% share, while block pallets and skids only accounted for 21% and 3% of the market, respectively. Softwoods accounted for 55% of the pallet market, while hardwood accounted for 45%. An estimated 326 million pallets were recovered and sold as recycled/ repaired or remanufactured pallets in 2016. The most common size of the recycled or remanufactured pallets was 48” x 40”, accounting for 69% of the recycled market.

Knowledge of the types of fungi inhabiting wood, their growth conditions, and level of damage is needed to design an effective and efficient preservation process. Researchers have tried to identify fungi that play a role in attacking wood products (impregnated wood), including the type and the role of these fungi in changing the quality of processed wood. Isolation was completed on fungal-attacked wood. The first isolation resulted in approximately 26 isolates, which were then grouped into 8 groups based on the macroscopic appearance of the fungus. Molecular identification of the fungi produced types of Aspergillus tamarii, Penicillium citrinum, Trichoderma longibrachiatum, Trichoderma reesei, and Fusarium solani. Chemical analysis using the Chasson Datta method was performed on attacked and non-attacked wood. A decrease was found in cellulose content and an increase in lignin content for impregnated wood attacked by fungi. It was suspected that there were cellulose-attacking fungi that consumed cellulose, which caused a decrease in cellulose content. An increasing lignin content was thought to be caused by phenols, produced by the delignification process by fungi and additional phenols from the impregnation process. Fourier transform infrared results revealed the presence of carbohydrates, showing that the degradation of cellulose by fungi produced simple carbohydrates.

Crop straw is a major agricultural residue and has been recently promoted as a main source for renewable biomass energy production in China. This study used the fuzzy analytical hierarchy process (Fuzzy AHP) model considering four major indicators to systematically evaluate the performance of four major crop straw energy utilization methods in the eastern Chinese province of Jiangsu. The utilization methods include straw power generation, straw gasification, straw liquefaction, and straw densification into briquette fuel. The results showed that environmental friendliness was the most important indicator that should be considered for straw bioenergy production in the province and that straw densification into briquette fuel was the most suitable straw energy utilization method. Under the policy goal proposed by the Chinese central government to use 20% of all crop straw waste for straw bioenergy production by 2030, the estimated results suggested that the optimal allocation towards straw energy production structure is 40.1% for straw densification into briquette fuel production, 35.3% for straw power generation, 19.6% for straw gasification, and 5% for straw liquefaction. The finding that straw densification into briquette fuel was judged to be the most favorable option could guide policy makers and investors to develop suitable straw energy technologies in Eastern China.

Oak (Quercus robur L.), iroko (Milicia excelsa (Welw.) C.C. Berg), and tauari (Couratari spp.) wood were subjected to cyclic thermo-mechanical treatment (CTMT). The densification temperature amounted to 100 °C or 150 °C. The greatest changes in the modulus of rupture (MOR) value of the iroko wood, depending on the number of thermo-mechanical modification cycles, were noted. The MOR of the iroko wood, densified at 100 °C or 150 °C, after second thermo-mechanical modification cycle was twice as high as before the modification. No significant differences were observed between the modulus of elasticity (MOE) of oak wood before and after one modification cycle. Similar dependencies were noted in iroko wood. The thermo-mechanical modification performed over two cycles led to the highest increase, by about 56%, in MOE in oak wood densified at 150 °C. It was demonstrated that modification at 150 °C had a negative impact on iroko wood, which was manifested in the lower compression ratio of iroko at 150 °C than at 100 °C.

A nano-film was developed using nano-fibrillated cellulose (NFC) obtained from banana (var. Poovan) pseudostem. The NFC was prepared by alkali treatment followed by bleaching and acidification, as described and characterized in the authors’ previous paper. The NFC was used as base material for the development of nano-film. The nano-film was prepared via solvent casting with NFC (4%), polyvinyl alcohol (5%), and polyacrylic acid (5%) at a v/v ratio of 5:8:1. The nano-film was characterized using ultraviolet-visible (UV-VIS) spectroscopy, Fourier transform infrared (FT-IR), thermal gravimetric analyzer, scanning electron microscopy (SEM), gas permeability tester (GPT), texture profile analyzer, and digital thickness gauge meter. The data showed that the developed nano-film was UV protectant, possessed strong cross-linking, had high oxygen barrier capacity, was thermally stable up to 356 °C, and had high tensile strength than conventional film. To assess the protective quality of developed nano-film, tomato fruits were covered, and the shelf life was determined using physiological and biochemical attributes. The study revealed that nano-film developed from NFC possessed tomato preserving capacity for 15 days under ambient storage condition. Overall, the data suggested that banana fibres could be a potential source of NFC to develop biodegradable nano-film.

To quickly evaluate the material properties of ancient wooden structure members on site, the larch species of northeastern China was used as the research object, and the nondestructive testing method of the stress wave and the micro-drill resistance meter were used to measure it. The variation laws of the larch wood’s cross and longitudinal property indexes were determined. According to the variation law of material property indexes, the detection divisions under the nondestructive testing technology of stress wave and micro-drill resistance instruments were divided, which provides a basis for improving the accuracy of on-site nondestructive testing. From the comparison of shade and light side data, it was found that there was little difference in material properties indexes. According to the change trend of larch wood with density, the pith, juvenile wood, mature wood, and overmature wood were divided, which provided a reference value for the study of wood growth laws.

Urea-formaldehyde (UF) resins were synthesized with different molar ratios and solid contents, and simultaneously they were cured under conditions of different pH values. The curing behaviors of cured UF resins were examined by synchronous thermal analysis (TG-DSC). The crystallinity of cured UF resin was analyzed by X-ray diffractometry. The gel time of cured UF resin was recorded by chemical methods. The results indicate that condensation reactivity leads condensation reaction and crystallization to play various roles during the curing process of UF resin. The condensation reaction and crystallization in the curing process interact to result in different structures of cured resin. A new mechanism for UF resin curing (reaction-crystallization) is thus proposed.