Research Articles

The objective of this study was to verify the applicability and preliminary results of an ultrasound methodology for the complete characterization of root wood. The tests utilized six species: Swietenia macrophylla, Gallesia integrifólia, Swietenia sp., Schinus molle, Handroanthus heptaphyllus, and Acrocarpus fraxinifolius. The results show expected elastic ratios between properties, indicating that although the properties can differ numerically from roots and other parts of the tree, the orthotropic wood behavior is maintained. The root densities were higher than those reported in the literature for trunk wood, but direct relationships among high density and stiffness or strength properties were not observed. The ultrasound tests allowed 12 elastic constants of root wood to be obtained and were feasible for root dimensions because only one specimen was required.

Inspired by the high adsorption efficiency of aerogels, a thiourea-modified nanocomposite aerogel consisting of nanofibrillated cellulose and chitosan was prepared via a facile method. The prepared novel aerogel was studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The adsorptions of the acidic and basic dyes (acid orange 7 and crystal violet) on the aerogel from aqueous solutions were investigated according to the adsorption kinetics and isotherms. The results indicated that a pseudo-second-order kinetic model more accurately described the adsorption process than a pseudo-first-order model, and the adsorption processes of both acid orange 7 and crystal violet on the aerogel were controlled by both inter-facial and intra-particle diffusions simultaneously. The Langmuir isotherm was a better model as compared to Freundlich model for the adsorption of dyes. The aerogel prepared by the facile approach is a promising material for practical applications in acidic and basic dye removal.

Butyric acid is a valuable chemical that has various applications in the chemical, pharmaceutical, food, and biofuel industries. Its bio-fermentation from lignocellulosic materials may be affected by some unwanted substrates that are generated during biomass pretreatment processes. In the present study, the potential inhibitory effects of two phenolic aldehydes (syringaldehyde and vanillin) on butyric acid fermentation by Clostridium tyrobutyricum were evaluated. The toxicity of syringaldehyde and vanillin on cell growth, xylose consumption, and butyric acid production was dosage-dependent. The butyric acid productivity decreased significantly with increasing concentrations of syringaldehyde and vanillin. C. tyrobutyricum demonstrated a broad tolerance to both syringaldehyde and vanillin and only moderate reductions in the maximum cell density were observed with up to 2.4 g L^-1 of syringaldehyde or vanillin in the medium. Both syringaldehyde and vanillin were assimilated by C. tyrobutyricum, and the metabolite products from vanillin caused considerable inhibition of the fermentation.

Chemical changes resulting from the thermal treatment of maple wood (Acer platanoides L.) through various steaming techniques were evaluated. Main wood components were isolated and characterized from the maple wood samples after steaming. Then, the isolated holocellulose and dioxane lignin were analyzed using ATR-FTIR spectroscopy. The effects of an increase in temperature and extension of the steaming period were seen primarily in the holocellulose and extractives contents, and less in the cellulose and lignin components. Certain steaming methods resulted in an increase in chemical composition, while others saw a decrease. The cellulose content of steamed maple wood was not considerably altered; however, the cellulose crystallinity did increase. The slight changes observed in this study can be attributed to several concurrent effects. While the lignin content in steamed maple wood showed only minimal changes, there were several changes in the structure of the lignin macromolecule. Demethoxylation, the decrease in the ratio of syringyl-propane to guaiacyl-propane units, and the formation of new alpha-C=O bonds were also observed. The hydrothermal treatment of wood also resulted in color changes of wood samples; the intensity of the change depended on the intensity of the treatment.

Conversion of lignocellulose into fermentable sugars and other chemicals usually requires multi-step unit operations, such as pretreatment, filtration/washing, and enzymatic saccharification and fermentation, which are the core steps responsible for increased operating expenses. A low-temperature NaOH/urea solution was shown to be an efficient cellulose solvent for overcoming the recalcitrance of lignocellulose by partially or fully converting rigid cellulose I crystallite into the more easily digestible cellulose II structure and by extracting a majority portion of the lignin and xylan from the lignocellulose. Higher yields of fermentable sugars were produced directly from corn stover in one vessel. This one-pot production of fermentable sugars was achieved via a combination process, including pretreatment with low-temperature NaOH/urea solution, pH adjustment, and enzymatic saccharification in a single reactor. This one-pot process liberated 86.3% of glucose and 71.3% of xylose in 24 h at an enzyme loading of 10 FPU/g and solid loading of 5%. Surfactant addition further enhanced enzymatic saccharification. The combination of low-temperature NaOH/urea pretreatment and enzymatic saccharification into a one-pot process is an efficient method for the conversion of lignocellulose into fermentable sugars suitable for conversion into fuels and other chemicals. Further studies related to lignin recovery and economical evaluation will be conducted.

Laminated bamboo with radial (LBR) and tangential (LBT) layered structures was manufactured using heat-treated moso bamboo and phenol-formaldehyde adhesive. The physical, mechanical, and fire-related properties were determined. The results showed that layer structure and heat treatment had an impact on the properties of laminated bamboo. LBR showed good mechanical properties, though heat treatment compromised its integrity somewhat. Heat treatment decreased the lightness and incre6/28ased the green-red index, blue-yellow index, saturation, and total color difference. The samples exhibited changes in two HRR peaks during the combustion process, corresponding to two main release stages for smoke production. Heat-treatment improved the heat rate release (HRR), total heat release (THR), and the effective heat of combustion (EHC) properties, but also they decreased the smoke performances, resulting in higher total suspended particulate (TSP), specific extinction area (SEA), CO, and CO₂ yield. LBR is suggested to be manufactured for possible use as a structural engineering material.

Green and biodegradable cellulose filters with controlled designer pore structures were prepared using organic solvent-based freeze casting. In this paper, the relationship between the different freeze media, including ethanol, isopropanol, and tertiary-butyl alcohol, and the microstructure of the porous filters was investigated. The results of the pore size distribution indicated that the pore channel size decreased remarkably when organic solvents were used as the freezing media. Moreover, the filters showed high filtration efficiencies, up to 99.70% and 99.66% for 0.5 µm and 0.3 µm particles, respectively, under a pressure drop of 180 Pa and at 32 L·min^-1 flow rate. The fabrication of cellulosic filters would not only make it a promising candidate for capturing fine particulate matter, but also provide a versatile approach to regulate and design a porous structure for materials applied in various fields.

Gelatin (GEL) obtained from animals is famous for its biocompatibility and biodegradability. However, its poor mechanical properties limits possible applications as bio-inks to fabricate tissue scaffolds through three-dimensional (3D) printing. In this work, a high strength hydrogel based on cellulose nanofibers and GEL (CNF/GEL) was designed for 3D printing. Scanning electron microscopy and breaking strength results indicated that a CNF filling content of 10% was the best content in the CNF/GEL hydrogels. The rheological properties of the samples with different solid contents were investigated, and the 10%-CNF/GEL-5 hydrogel was proposed for 3D printing. Then, a printing strategy with optimal conditions, including a crosslinking procedure for obtaining a 3D scaffold, was proposed. The biocompatibility of G-10%-CNF/GEL-5 was also investigated using CCK-8 and Hoechst 33342/PI double-staining assays. These results confirmed that the 10%-CNF/GEL-5 composite hydrogel has potential to be used as a 3D bio-ink for application in tissue repair.

A series of bimetal-doped beta zeolites were prepared via a simple post-synthesis strategy including dealumination and metal ion incorporation. The incorporation of ferromagnetic metals into lattice sites of Sn-beta was evidenced by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The high reduction temperature (1094 K) of cobalt in Co-Sn-beta zeolite, as determined by temperature programmed reduction (TPR), confirms that Co interacts strongly with the zeolite support, consistent with lattice tetrahedral (Td) coordination. Co-doped Sn-beta zeolite was found to be a promising Lewis acid catalyst together with a carbon solid acid for the conversion of furfural to isopropyl 4-oxovalerate (i-PL) and γ-valerolactone (GVL). The highest total yield of 92.02% was obtained after reaction for 16 h at 160 °C, including 48.3% i-PL, 37.7% GVL, and 6.0% levulinic acid (LA). The catalysts could also be applied as robust catalysts in glucose conversion to 5-hydromethylfurfural. Zeolite catalysts designed and prepared by this strategy contain multiple metals, enhancing their flexibility and adjustability of function via changing the species and ratio of metals to derive optimized catalysts for specific reactions.

This study demonstrated the strength of a theoretical model founded on the Box-Behnken experimental design method to determine the surface roughness (Ra parameter) of solid Oriental beech (Fagus orientalis Lipsky) wood. The working parameters (sanding belt grit size of 60 to 100, feeding speed of 4 m/min to 10 m/min, and sanding cutting depth of 0.1 mm to 0.3 mm) of a wide belt sanding machine were determined. The Ra of the samples was experimentally described so that the experimental results were also remodeled with the Box-Behnken method to find the optimum parameters for the lowest Ra. An adjusted correlation factor of 93.6% for the Ra confirmed the compatibility between the experimental and theoretical findings. The high correlation (strength) allowed for a more detailed discussion of the effect of the working parameters on the Ra. The theoretical approach showed that the grit size factor had the largest effect on the Ra compared with the other factors. The optimum parameters were found to be a grit size of 100, feed speed of 4 m/min, and sanding depth of 0.1 mm for a minimum Ra for Oriental beech wood. The experimental data supported these parameters.