Wood Science and Technology最新文献

Cellulose nanofibers (CNFs) were isolated and prepared from six different plant sources (Nordic pine, poplar, cotton, flax, bamboo, and pineapple leaf fibers) through a carboxymethylation-homogenization treatment. The surface morphologies, size distributions, and chemical structures of the CNFs and their microfibers were investigated in detail. Atomic force microscopy (AFM) analysis showed that all kinds of CNFs had uniform diameters of less than 10 nm. However, the length and aspect ratio of CNFs exhibited significant differences due to the differences of anatomical characteristics from pulp species. Among these six nanofibers, the pineapple leaf-based nanofibers had the highest length of ca. 2.21 μm and aspect ratio of ca. 1263. Meanwhile, the resulting pineapple leaf-based nanocellulose film possessed the strongest tensile strength (229.0 ± 9.8 MPa) and toughness (33.9 ± 2.9 MJ/m³). Interestingly, the aspect ratio of cotton nanofibers was only 556, lower than that of bamboo, Nordic pine, and flax nanofibers, but the tensile strength (210.6 ± 4.8 MPa) and toughness (22.4 ± 0.6 MJ/m³) of cotton-based nanocellulose film were second only to the pineapple leaf-based nanocellulose film. The critical reason is that the cotton-based nanocellulose exhibited the highest crystallinity index (76.6%), superior to the other source-based nanocellulose. These results suggested that the high aspect ratio or high crystallinity are responsible for the excellent mechanical strengths of the nanocellulose film. This work sheds light on the preparation and selection of highly spindly or crystalline nonwood nanofibrils, suggesting that the pineapple leaf or cotton nanofibers have great potential as strength additives for nanocomposites.

Condensed tannins (CTs) characterized by a low degree of polymerization (DP) are recognized to have substantial value for applications across diverse industrial sectors, including food production, pharmaceuticals, and wood adhesive manufacturing. To acquire CTs with a low DP, the depolymerization of bayberry tannins (BTs) through a novel approach utilizing UV light-driven photocatalytic degradation, facilitated by the ultrasonic dispersion of TiO₂ nanoparticles was investigated. Under the optimal degradation conditions (a tannin concentration of 6%, a TiO₂ nanoparticles loading amount of 0.20%, and a degradation time of 4 h), the study delineated a discernible linear relationship correlating both the degradation time with the formaldehyde reactivity of the photocatalytic degradation products, and the formaldehyde reactivity with the mean degree of polymerization (mDP) of these photocatalytic degradation products. With the establishment of these correlative relationships, it is feasible to systematically control the degradation process of BTs. The photocatalytic degradation process adhered to the following mechanism: The degradation process of BTs is initiated by the cleavage of the C4-C8 bond which, at the incipient stage of degradation, results in the elimination of one gallocatechin gallate unit and one gallocatechin unit, or alternatively, the removal of a gallocatechin dimer. During the advanced stages of degradation, the opening of the C ring gives rise to different derivatives. Upon establishing optimal degradation parameters, it was observed that the primary constituents of the photocatalytic degradation products were dimers. The utilization of photocatalytic degradation exhibited an ability to break down condensed tannins in a manner that is both controllable and in an environmentally friendly way.

The exploitation of low-cost, non-fossil membrane materials with flourishing pore structure is essential to complete an organic dye wastewater treatment in Fenton-like catalytic technology. The accessible and scalable veneer functionalized Fenton-like catalysis has been manufactured to decolorize the effluents by a hydrogen peroxide-Mn-based oxides system. The nanocatalyst of Mn-based oxides has been loaded on the veneer surface by the hydrothermal in-situ growth, which could accomplish the coupling of Fenton-like catalyst and membrane technology. Fir and poplar veneers with unique three-dimensional porous structure have been investigated in detail to manifest the respective performance of decolorization during the dye wastewater treatment. This work not only has invented a promising membrane material coupling with Fenton-like catalysis to dispose dye wastewater, but also provides a reference in high-performance membrane design of biomimetic membrane.

Turning lignin from black liquor waste into value-added bioactive agents is one of the possible routes for improving the sustainability and profitability of lignocellulosic industry. However, due to chemical and structural variability of lignin, it is necessary to isolate specific lignin fractions from black liquor with the purpose to achieve samples with unique chemical and structural characteristics and therefore, specific biological activities. In this study, poplar lignin fractions isolated from Kraft black liquor by sequential acid precipitation at pH´s 7.5, 5 and 2.5 (denoted as P-7.5, P-5 and P-2.5) were characterized according to their physicochemical, antioxidant and antibacterial properties. In general, lignin fractions displayed a wide elimination of lateral chains (aryl-β ether and C–C) and, therefore a high phenolic content and low molecular weight, as the pH sequential precipitation was decreased from 7.5 to 2.5. Moreover, thermal analysis revealed that the P-7.5 lignin fraction showed higher thermal stability than P-2.5 and P-5. In terms of antioxidant activity, the P-7.5 lignin fraction, with a higher S/G ratio and a less oxidized structure compared to P-5 and P-2.5, exhibited higher antioxidant activity. In addition, lower antibacterial effect was observed for all lignin fractions against Escherichia coli compared to that obtained against Staphylococcus aureus. Among them, the P-2.5 and P-5 fractions, with higher phenolic content and lower molecular weight values than P-7.5, showed a greater antibacterial effect against S. aureus.

Dye wastewater produced from industry production is difficult to degrade naturally. Natural wood possesses a hierarchical and three-dimensional (3D) interconnected microstructure, making it a desirable material for water treatment. However, limited water transport pathways can reduce the efficiency of removing high-concentration organic dyes. To address this, we present a low-cost, scalable, and efficient cross-flow Ag/wood composite filter by combing the structural design and hydrothermal treatment using a silver-ammonia solution. Silver ions (Ag⁺) are effectively reduced to silver nanoparticles (Ag NPs) by wood lignin and then anchored by hydroxyl groups in the cellulose and hemicellulose of the wood. Importantly, the incorporation of Ag NPs does not compromise the 3D porous structure of the wood. Diagonal grooves and exposed channels on both sides of the filter guide pollutants, ensuring extensive interaction with Ag NPs along elongated reaction pathways and through microstructural vessel disturbances. An 8 mm-thick cross-flow Ag/wood composite filter, featuring grooves with a diameter of 15 mm and a depth of 4 mm, achieves a remarkable 99% degradation efficiency of methylene blue (MB) at a water flux of up to 1775 L/(m²∙h). The performance in water flux and decolorization efficiency hinges significantly on groove diameter, groove depth, and filter thickness. This cross-flow Ag/wood composite filter represents a promising advancement for rapid and effective removal of various organic pollutants in a single-step process, showcasing extensive potential for applications in water treatment. This work aims to enhance clarity and readability while maintaining the technical details and impact of the research.

This paper investigates the impregnation of Japanese cedar (Cryptomeria japonica D. Don) with water using ultrasound irradiation, followed by immersion in water containing bulk nanobubbles (NBs). Cavitation bubbles generated during ultrasound irradiation mechanically remove extractives from the wood surface, enhancing the mass transfer of water into the wood. Water containing bulk NBs has a lower surface tension compared to pure water, enabling superior permeability into narrow spaces. However, the application of water containing NBs for wood impregnation post-sonication remains underexplored. In this study, wood was subjected to ultrasound irradiation at 38 kHz, followed by immersion in water containing bulk NBs, to determine the optimal sonication time and NB concentration for efficient impregnation. The results indicate that water uptake by the wood initially increases and then decreases with increasing NB concentration and sonication time. Optimal sonication time and NB concentration resulted in highly efficient impregnation.

A reed (Arundo donax) was acetylated to prevent serious cheilitis (reed allergy) in woodwind musicians in contact with the vibrating plate made of the reed. The reed was acetylated almost completely at 120 °C for 8 to 24 h. The maximum weight% gain (WPG) of the reed was lower than that of wood, reflecting a lower number of active reaction sites. The WPG of the inner part of the reed was slightly higher than that of the outer part, probably because the reactivity of the parenchyma cells is higher than that of the bundle sheaths. The acetylated reeds were tested by eleven skilled musicians suffering from the reed allergy. Eight musicians reported no allergic reactions. Three musicians reacted with the acetylated reed, but the reactions were much weaker than those induced by the unmodified reed. Thus, acetylation has been proven effective in preventing reed allergy. The patch test was not sufficient to detect allergies because although some musicians tested negative in the patch test, their mouths reacted seriously.

This study presents the development of a wood sponge (WS) modified with MnO₂ nanorods (MnO₂/WS) derived from balsa natural wood, an abundant and environmentally friendly raw material, for the adsorption of organic solvents, oils, and heavy metal ions from water. The MnO₂/WS composite exhibits an exceptionally low density of 0.014 g cm^− 3 and a high porosity of approximately 97%. It demonstrates consistent sorption-desorption performance over 20 cycles. Zeta potential analysis reveals that MnO₂ nanorods carry a negative charge (-22.31 mV) at pH 4.68, indicating their affinity for adsorbing positively charged heavy metal ions, which are commonly found in industrial effluents. Moreover, WS shows remarkable mechanical robustness, enduring 1000 stress-strain cycles with high shape recovery, ensuring its durability under operational conditions. The data highlight several strengths of MnO₂/WS, including cost-effective production process, high reusability, remarkable sorption capacities for carbon tetrachloride and soybean oil (29.56 and 17.65 times its mass, respectively), and efficient performance. Its capability to produce potable water from real industrial effluents positions MnO₂/WS as an ideal solution for addressing water crises.

This study investigated the effects of high-intensity microwave (HIMW) treatment on the mechanical properties of radiata pine wood. The treatment, conducted on sapwood and heartwood with 60% initial moisture content, involved varied microwave energy densities: 60, 80, and 100 kWh/m³. Tests evaluated tensile and compressive properties in three directions, alongside shear strength and bending properties. Acoustic emission (AE) and digital image correlation (DIC) techniques probed damage evolution under bending loads before and after HIMW treatment. As microwave energy density increased, compressive, tensile, and shear strength decreased, with heartwood being the most susceptible. Substantial reductions occurred in longitudinal compressive properties and tensile properties perpendicular to the grain. After HIMW treatment (80 kWh/m³ and 100 kWh/m³ for sapwood and heartwood, respectively), although there was a slight decrease in the modulus of elasticity and bending strength, there was a significant increase in bending plasticity. HIMW-treated specimens exhibited more high-frequency AE signals during elastic–plastic deformation, indicating more frequent fractures in the treated wood during three-point bending. Changes in the microscopic structure of the wood specimens caused by HIMW treatment increased the damage growth rate and stress redistribution efficiency during loading, augmenting the bending plasticity of wood.

In view of developing upcycling strategies for hardwood Kraft lignin, hydroxy-methylation of Eucalyptus Kraft lignin under alkaline conditions (pH 9 and 11) at different temperatures (50 °C and 70 °C) was studied in the present effort with the double objective of optimizing the reaction conditions and understanding the functionalization mechanism of C₅ in either terminal or internal guaiacyl units during hydroxy-methylation. Formaldehyde consumption was estimated via titration of the oximated free formaldehyde; the hydroxy-methylation degree under the reaction was estimated by calculating the ratio in Condensed hydroxyl/Guaiacyl (Condensed OH/G-OH) via a new difference UV-spectroscopy. The reliability of the difference UV-method results for the analyses of the hydroxy-methylated lignins was statistically analysed and compared with that of vacuum-dried and sonicated samples. Hydroxy-methylated samples were then fully characterised by NMR (³¹P and HSQC) and GPC. The reaction temperature of 50 °C, pH 11, and period time of one hour resulted as the optimal conditions for the hydroxy-methylation, preventing the side-reactions leading to the formation of dimethylene-glycol addition products. The ³¹P and ¹H–¹³C HSQC NMR revealed the absence of undesirable formaldehyde Cannizzaro by-products and the lack of hydroxymethyl groups in the aliphatic side chain under the studied conditions. GPC analyses, comparing two methodologies, revealed increases in molar mass of the hydroxy-methylated samples upon the formaldehyde addition. The selective hydroxy-methylation at the C5 guaiacyl site demonstrates that Eucalyptus Kraft lignin is as a promising candidate for resol production.