Volume 15 Issue 4

Bamboo-based activated carbon was made using the activating agents KOH and KMnO4 at high temperature. This study examined the ability of unmilled and ball-milled bamboo activated using KOH or KMnO4 to fulfil the activated carbon standard parameters. Chemical activation was done using KOH and KMnO4 at 2.5% and 5% concentration, heated at 800 °C, and steamed for 1 hour. Sample size was reduced to 500 nm using high energy ball-milling at 500 rpm for 80, 150, or 180 min. Analysis included the yield, water content, ash content, volatile matter content, burn-off weight percentage, morphology analysis, functional groups (Fourier transform infrared spectroscopy, FTIR), crystallinity analysis (X-ray diffraction, XRD), and Brunauer, Emmett, and Teller (BET) analysis. Ball-milling treatment for 150 min produced activated carbon of 449 nm in size and a particle distribution index (PDI) score of 0.66. Ball milled activated carbon from the experiment had a pore radius ranging from 1.18 to 2.49 nm. The activated carbon that met the criteria of ANSI/AWWA B604-12 (2012) standard for moisture content, iodine number, and JIS K 1474 (1967) standard for methylene blue adsorption level and surface area were milled activated carbon with activator KMnO4 2.5%.

The surface roughness of bamboo is a factor that determines the processing quality. The effects of spindle speed, feed speed, and cutting depth on the surface roughness of bamboo were studied using the orthogonal design test method. The results were analyzed using range analysis, main effect analysis, interaction analysis, and variance analysis to determine the effect of cutting parameters on the surface roughness of bamboo. The feed speed had a greater effect on the surface roughness of the bamboo in the tangential section; the spindle speed had a greater impact on the surface roughness of the bamboo in the cross section. The cutting depth had a greater impact on the surface roughness of the bamboo in the radial section. For the surface roughness on the tangential, cross, and radial sections of the bamboo, there was a relationship with the cutting parameters. A mathematical model for the analysis of surface roughness was established by response surface method. Also, contour and surface plots based on regression models showed the correlation between surface roughness and all possible pairwise combinations of three cutting parameter variables. The cutting technology with the best surface quality was determined by optimization analysis.

The aim of the study was to determine the effect of honeybee wax impregnation on the antifungal, larvicidal, water uptake, color, and mechanical properties of wood. Wood samples (poplar, Scots pine, beech, and lime) were impregnated with melted honeybee wax under vacuum. The wax-impregnated samples were exposed to the wood-decay fungi Trametes versicolor and Neolentinus lepideus for 8 weeks. The larvicidal effect of the beeswax was tested against European old house borer (Hylotrupes bajulus L.). Water uptake, color measurements, and surface hardness were also tested. According to the obtained findings, a 34.6% mass loss was seen in the poplar control wood, and only 3.9% mass loss was found in the 100% beeswax-impregnated samples. The results showed that H. bajulus larvae could digest honeybee wax with wood when beeswax surface treatment was applied. Additionally, an average of 30% larvae mortality rate was achieved on beeswax-treated wood surfaces, compared to a 2.5% rate on the controls. However, when wood was deeply treated with beeswax, larval mortality reached 100%. In the water uptake test, beeswax-treated samples showed water repellent efficiency. The lowest water uptake (24.2%) was obtained in poplar wood treated with 100% beeswax, compared to 92.6% in the poplar control in 96 h immersion time. With the beeswax treatment, a* and b* color values increased, while the L* values decreased.

A consolidated bioprocessing (CBP) using Clostridium thermocellum DSM 1237 for bioethanol production in anaerobic bottles and a 3-L fermenter from biomass was investigated. The effects of key operational parameters including different carbon sources, temperature, and substrates on the metabolic performance of the strain were firstly evaluated. It was found that ethanol yield reached 0.60 g/L with a cell biomass of 0.80 g/g at the optimal temperature of 60 °C with 0.5% (w/v) cellobiose. Further experiments indicated that sugarcane bagasse (SCB) could be utilized to efficiently culture this strain. Ethanol yield reached 0.68 g/L (65.8% of theoretical yield) from alkali-pretreated SCB. In the subsequent 3-L fermenter trial, the maximum ethanol 0.86 g/L (83.3% of theoretical yield) was achieved, with enzymes enriched in both cellulase and xylanase. The CBP provided enzymes on-site and integrated hydrolysis and fermentation in one-step, which might be an effective approach for economic bioethanol production.

Submerged fermentation with single or mixed metal ions as inducers was used for laccase production from white rot fungi. Mixed metal ions were used for the first time as inducers for Pleurotus ostreatus and Flammulina velutipes to enhance laccase activity. The maximum laccase activity from P. ostreatus in basal media, metal ion media 1 containing copper ion, metal ion media 2 containing manganese ion, metal ion media 3 containing manganese and copper ions, metal ion media 4 containing ferrous ion, metal ion media 5 containing manganese and ferrous ions, metal ion media 6 containing ferrous and copper ions, and metal ion media 7 containing manganese, copper and ferrous ions were, respectively, approximately 21.5-fold, 4.7-fold, 14.9-fold, 16.9-fold, 4.0-fold, 11.0-fold, 12.7-fold, and 24.8-fold higher than that from F. velutipes. The combination of copper and manganese ions as inducers was superior to that of a single copper ion or manganese ion. The maximum laccase activity of P. ostreatus rose in media containing manganese and copper ions. The single copper ion as the inducer for enhancing laccase activity was more suitable for F. velutipes. These findings are helpful in selecting the appropriate single metal ion or mixed metal ions to enhance laccase activity.

A sandwich-structured natural fiber-based magnetic composite, without the use of a binder, was developed in this study. It was fabricated via in situ synthesis, densification, and magnetron sputtering processes. The chemical composition, crystal structure, microstructure, and thermal stability were characterized via X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, X-ray diffraction, scanning electron microscope, and thermogravimetric analysis. The hydrophobic, magnetic, and electromagnetic interference shielding properties were investigated by measuring the static water contact angle, the magnetic hysteresis loops, and the shielding effectiveness. The resulted composites exhibited a unique inner structure with a larger iron oxide size and content (492 nm and 26.1 wt%) on the interlayer surface in comparison to the core layer (135 nm and 18.7 wt%). The magnetic response can be controlled by the loaded iron oxide content and the copper film deposition. Sputtering copper film changed the surface free energy, and created rough micro-/nanostructures, which yielded a highly hydrophobic nature (133° in water contact angle), and approximately 99.2% of the electromagnetic energy was shielded by the 0.8 mm thick composite.

To improve the nematode-infected pinewood application value, an effective strategy was developed based on the cultivation of Flammulina velutipes to process the pinewood that was infected by the nematode Bursaphelenchus xylophilus. Different treatments were compared to determine the optimal method to obtain the highest yields of reducing sugars. The results showed that the cultivation of F. velutipes using the nematode-infected pine sawdust overcame the disadvantage of cultivation by using healthy pine sawdust, and whether fungal infection that happened in the period of pine wilt disease or during the cultivation of F. velutipes both can contribute on the degradation of the polysaccharide content. A high yield of reducing sugars can be obtained using 2% dilute sulfuric acid at 121 °C for 1 h to treat recyclable nematode-infected pine sawdust after the cultivation of F. velutipes. Additionally, the results showed that fungal infection that occurred in the period of the pine wilt disease and during the cultivation of F. velutipes in addition to acid hydrolysis effectively converted hemicellulose to reducing sugars.

Cross-laminated timber (CLT) is increasingly used in building construction worldwide. Durability of CLT against fungal attack has yet to be fully explored. Water intrusion in mass timber can yield dimensional changes and microbial growth. This study evaluated the performance of CLT coated with various water- and solvent-based stains commercially available in the United States. Twelve coatings were tested for moisture excluding effectiveness, water repellency effectiveness, volumetric swelling, and anti-swelling efficiency. Only five coatings repelled water, limiting dimensional changes. A modified version of AWPA E10-16 (2016) was performed to evaluate decay of the coated CLT samples. Weight losses were recorded after 18 weeks’ exposure to the brown-rot decay fungus Gloeophyllum trabeum. In accelerated mold testing, coated CLT samples were grown in chambers containing spores of Aspergillus sp., Rhizopus sp., and Penicillium sp. for 29 d and assessed visually for mold growth. In both tests, coating C (transparent, water-based, alkyd/acrylic resin) performed the best among the tested coatings. Mold growth was completely prevented, and weight loss caused by G. trabeum was approximately 1.33%. Although coating C prevented decay for 18 weeks, coatings are not intended to protect against decay fungi. However, they may offer short-term protection during transport, storage, and construction.

X-ray microdensitometry was performed on small wood samples after fungal exposure to assess wood density loss and its variability within a hybrid larch population. Microdensitometry was applied to thin wood slices obtained from increment cores collected from standing trees before and after 4 weeks of exposure to Coniophora puteana fungus. Density loss rates were measured and compared to mass loss percentages calculated on wood blocks following a 16-week decay test according to CEN TS 15083-1 (2005). The relationship between the standard mass loss and the density loss percentages was weak. Several explanations for the results are presented in this work, and methodological improvements are suggested to achieve a more accurate comparison. The proposed screening test has several advantages over the current standard method, as it is less invasive for the tree, less time consuming, and is therefore better suited for genetic studies and breeding. As predicted, due to extractive content variation and fungus behaviour, density loss after 4 w was more important in earlywood than in latewood and in inner heartwood than in outer heartwood. The new method also better determined the differences in decay among trees within the larch population than the standard method at 16 w.

Bentonite and polyamidoamine epichlorohydrin (PAE) resin were added sequentially as a binary system to improve the properties of the paper, especially the wet strength. The results showed that the dry tensile index, the wet tensile index, and the folding endurance of the paper could be improved with only the use of polyamide polyamine epichlorohydrin resin. However, a binary system of polyamide polyamine epichlorohydrin resin and bentonite was more effective. When 0.8% polyamide polyamine epichlorohydrin resin and 0.75% bentonite were added, the dry tensile index, the wet tensile index, and the folding endurance of the paper increased by 37.8%, 2780%, and 281%, respectively, when compared to the control sample. The measurements of the water retention value and the percent fines retention of the pulp showed higher values after being treated with the binary system than being treated by polyamide polyamine epichlorohydrin resin alone. Scanning electron microscopy analysis indicated that a binary system of polyamide polyamine epichlorohydrin resin and bentonite could increase the combination of fibers in paper.