Research Articles

The oxidation conditions and adsorption ability of Cu (II), Cd (II), and Pb (II) from an aqueous solution of sodium hypochlorite-oxidized fir bark powder were investigated. The optimum amount of NaClO was 9.6%, the pH was 9, and the oxidation time was 120 min. Batch adsorption experiments were carried out with various times, pH values, and initial metal ion concentrations. The adsorption isotherms and kinetics of adsorption were also studied. The maximum adsorption capacity of oxidized fir bark was 0.983, 1.223, and 0.966 mmol/g for Cu (II), Cd (II), and Pb (II), respectively, within 30 min at pH 5, higher adsorption capacity than that of unoxidized fir bark. The isothermal adsorption of heavy metal ions in aqueous solution was a good fit to the Langmuir equation, with a coefficient of determination, R2, above 0.99. The adsorption of fir bark on metal ions can be appropriately approximated by a pseudo-second order adsorption kinetics model. Results indicate that the fir bark powder modified with sodium hypochlorite can adsorb large amounts of metal ions and could be a good adsorbent for the removal of Cu(II), Cd(II), and Pb(II) from aqueous solution.

Tests were carried out to determine the bending moment capacities of L-shaped mortise and tenon furniture joints under both compression and tension loadings. The effects of wood species (Turkish beech and Scotch pine), adhesive type (polyvinylacetate and polyurethane), and tenon size (width and length) on the static bending moment capacity of joints under the same loading conditions were investigated. The results of the tests indicated that the moment capacity increased as either tenon width or length increased. The results also indicated that tenon length had a greater effect on the moment capacity than tenon width. In both compression and tension tests, Turkish beech joints were stronger than Scotch pine joints, and PU joints were stronger than PVA joints. An empirically derived expression was developed to estimate the average ultimate bending moment capacity of joints under compression and tension loads as functions of the wood species, the adhesive type, and the tenon size.

Because of a complex chemical ultra-structure of lignocellulosic biomass, pretreatment is a necessary step for its conversion into bio-ethanol. In the present study, pretreatment conditions using the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl) were optimized for a relatively new model energy crop, hybrid Pennisetum (P. americanum × P. purpureum) to maximize the yield of fermentable sugars (glucose). The design of experiment programs employed a central composite design (CCD), with variables of temperature (102 to 187 °C), retention time (0.5 to 5.5 h), and solids loading (2 to 15 wt%). These factors were further optimized using response surface methodology (RSM). The proposed quadratic model to predict the glucose recovery from hybrid Pennisetum was verified by variance analysis (ANOVA). The model displayed high F and R2 values, indicating that it could be successfully used to identify the relationship among the independent variables studied. A maximum glucose recovery of 72.2% was found with temperature conditions of 139 °C, 2.97 h retention time, and 9.1 wt% solids loading.

An environmentally-friendly wood adhesive was developed by blending konjac glucomannan (KGM), chitosan (CH), and polyvinyl alcohol (PVA) together. The viscosity of the KGM-CH-PVA (KCP) blend adhesive was determined, and the morphology of the film was observed using scanning electron microscopy (SEM). The KCP blend adhesive was applied to plywood during the manufacturing process, and the effects of the KGM, CH, and PVA contents on the bond strength was investigated. Results showed that KGM greatly increased the viscosity of the KCP blend adhesive, whereas the addition of PVA decreased the viscosity in the test range. The SEM observations showed that the KCP blend adhesive was homogeneous. The bond strength of the plywood that was treated with KCP blend adhesive increased with increasing KGM and CH concentrations, and desirable performance could be obtained with a total solids content of 4.6%. The KCP blend adhesive with 2.0% KGM, 2.0% CH, and 0.6% PVA exhibited a comparable bond strength with phenol formaldehyde. Findings suggest that the KCP blend adhesive can be used as a wood adhesive with all raw materials, having the advantage of being environmentally friendly.

The weathering performance of wood coated with a combination of rutile TiO2 hierarchical nanostructures and a sol-gel deposit of alkoxysilanes was determined by exposing three sets of specimens to UV light and water spray. The first set consisted of specimens coated with a mixture of methyltrimethoxysilane (MTMOS) and hexadecyltrimethoxysilane (HDTMOS). The second set consisted of specimens coated with nanostructural TiO2 followed by a mixture of MTMOS and HDTMOS. The third set consisted of uncoated control specimens. The wood coated with TiO2 followed by a mixture of MTDMOS and HDTMOS exhibited significantly less surface color change and weight loss as a result of UV light-induced degradation and erosion from water spray in comparison with the other groups. However, the coated surfaces were gradually transformed from hydrophobic to hydrophilic. Despite this apparent weakness, the MTMOS/HDTMOS/TiO2 coating, with superior photostabilization properties and resistance to surface erosion, may be useful for improving the weathering performance of wood coated with semi-transparent wood stains.

The influence of eccentricity ratio on the behaviour of 50 parallel bamboo strand lumber (PBSL) column specimens was studied under eccentric compression. The load-strain and load-deflection relationships were obtained from column tests, and the detailed failure modes for all specimens are reported. The eccentricity ratio is the main influencing factor on the bearing capacity of the columns, and the ultimate load values decreased with an increase of the eccentricity ratio. Both the ultimate middle deflection values and the absolute ultimate longitudinal strain values initially increased with the increase of the eccentricity ratio, and then stabilized or decreased slightly when the eccentricity ratio was bigger than approximately 0.8. The absolute ultimate lateral strain values for both face A (bracket side or compression side) and face C (tension side) performed similarly with the increasing of eccentricity ratios, increasing initially and then stabilizing or decreasing slowly. An equation for calculating the eccentricity influencing coefficient of PBSL columns is proposed. The calculation results obtained from the equations agreed well with the test results.

Wood-based materials are used to manufacture various types of panels, including particleboard, fiberboard, and plywood, and they can also be used to manufacture furniture as well as interior and exterior building materials. However, wood-based materials exhibit a number of problems, including the emission of indoor air pollutants from adhesives used during production and their inherent fire risk. To date, a number of studies have investigated the emission of indoor air pollutants, and in recent years, there has been an increasing amount of interest in the flame-retardant performance of wood-based materials. In this study, the use of carbon materials was studied to improve the flame-retardant performance of wood-based materials. A comparison was made with various methods that are currently in use. The thermal conductivity was measured by the TCi method developed by C-Therm Technologies Ltd to evaluate the energy characteristics of wood-based materials that are used as interior materials.

Rosewood furniture and handicrafts are appreciated by Chinese people on account of their rich aroma and pleasing feel. The unique characteristics of rosewood are attributed to the presence of certain organic compounds in its gum canal and parenchyma cells. However, modern wood drying is different from traditional technology with respect to protecting those valuable organic compounds in wood. In this study, to investigate the valuable organic compounds in Dalbergia bariensis, and the effect of drying treatments on their preservation rates, wood extracts, untreated and treated with conventional drying (CD), vacuum drying (VD), and vacuum freeze drying (VFD), were analyzed by gas chromatography- mass spectrometry (GC-MS). The results indicated that there were some compounds with obvious pharmaceutical functions in Dalbergia bariensis, which can be used to improve the furniture function in health care. Also, the preservation of these compounds was affected by drying treatment; VFD drying preserved the maximum amount of organic compounds in wood.

The cellulolytic and ethanologenic bacterial community is a promising candidate for the production of bioethanol from lignocellulose. In this study, by artificially changing the ratio of Clostridium thermocellum in the cellulolytic consortium H, ethanol production was increased by 72.7%. Metatranscriptomic analysis was used to elucidate the contribution of Clostridium thermocellum to ethanol production. A comprehensive analysis of genes mapped to the Clostridium thermocellum ATCC 27405 genome was performed; the identified gene expression differences related to cellulosic ethanol pathways were carefully studied. The results indicated that the majority of genes involved in lignocellulose degradation, sugar transport, cellodextrin breakdown, glycolysis, and ethanol synthesis were up-regulated in C. thermocellum when added to H (HCt). More than 18 cellulosome-related genes had 15-fold or greater increased expression. The results illustrate the role of C. thermocellum in the cellulolytic consortium H and HCt and provided useful information for identifying genes and preferred pathways. These results will aid in the metabolic and genetic engineering of bacterial strains for more efficient biofuel production.

The article deals with the influence of the tool wear of several circular saw blades, each with different numbers of teeth (24, 40, and 60), on the quality of a machined wood surface. The surface quality was evaluated based on the surface roughness, which was represented by the surface arithmetical mean deviation Ra. To achieve the conditions of manual sawing, the saw blade was shifted into the cut with a constant feed force of 15 N. The results showed that the 40-tooth saw blade obtained the most suitable results; it exhibited the longest sawn distance and reached moderately good values of tool wear. The average values of surface roughness ranged from 3.9 to 14.5 µm, and the saw blade wear increased proportionally with sawn distance. The tool wear of the saw blade had no unambiguous effect; increase in tool wear did not lead to a deterioration of surface quality.