Volume 14 Issue 2

Wood sanding is one of the most expensive processes in the woodworking industry, and little is known about the factors that influence the final quality of wooden parts. For this reason, studies involving different wood treatments, such as thermal treatment, have been developed to produce better surface qualities. The objective of this work was to verify the influence of thermal treatment of the wood species Corymbia citriodora before the sanding process on the surface quality of the wood pieces. The surface finishes of the sanded natural and heat-treated wood were compared. Sanding was performed using two sandpaper grades, 80 mesh and 120 mesh, with abrasive grains of aluminum oxide. The sanding process was performed by flat horizontal sanding parallel to the fibers. Six specimens were used for each sandpaper grade. Initially the specimens were heat-treated at 120 °C, 160 °C, and 200 °C for 2 h, and then they were subjected to sanding. For the analysis of the surface quality of the wood pieces, the average roughness was used. From the obtained results, it was concluded that the heat treatment considerably reduced the roughness of the wood for both sandpaper grit sizes, and it facilitated the final finishing of the wood pieces.

As an important sustainable source of biomass, lignocellulosic materials are highly recalcitrant to biotransformation, which limits their use and prevents economically viable conversion into value-added products. Ionic liquids (ILs) have emerged as attractive solvents for lignocellulosic biomass pretreatment in the production of biochemical feedstocks. In this work, a mixture of wood powder and waste paper was dissolved in the ionic liquid 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). Composite films were made from the regenerated lignocellulosic materials in [AMIM]Cl by adjusting the ratio of the raw materials. The physical and mechanical properties of biomass composite films were determined by optical microscopy (OM), Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD), and tensile strength tests. The results indicated that lignocellulosic materials were dissolved in [AMIM]Cl by destroying inter- and intramolecular hydrogen bonds between lignocelluloses. With increasing waste paper cellulose content, the dissolution of the fir powder in [AMIM]Cl was accelerated, and the tensile strength and elongation at break of the composite films increased. The rate of dissolution initially rose rapidly with increasing content of waste paper cellulose content, but the rate leveled off when the content was above 40%. This research highlights new opportunities for biodegradable composite films made from waste biomass.

Agricultural wastes are potential sources for the commercial production of biofuels because of their availability and low market price. In the present study, the viability of producing bioethanol from three varieties of cassava pulp and peel (CPP) was studied. Acid hydrolysis was performed by dispersing 20% w/v CPP in 100 mL of hydrochloric acid. Biological hydrolysis was performed by inoculating gelatinized CPP paste with Aspergillus niger. A set of un-gelatinized control samples was used to investigate the effect of heat pretreatment on the reducing sugar yield. The hydrolyzed samples were fermented with Saccharomyces cerevisiae, and the ethanol yield was determined. The reducing sugar yield was 110.7 g/L, 100.4 g/L, and 96.7 g/L from acid hydrolysis of three cassava varieties, while a yield of 98.9 g/L was obtained from cassava peel at 0.7 M and 50 min. The gelatinized pulp from the samples hydrolyzed with A. niger consistently produced more reducing sugar than the control samples. The highest ethanol yields were 54.8% and 33.1% obtained, respectively, from a heat-pretreated variety and cassava peel. Results from the conversion of cassava peel readily bring to light a more useful way of managing cassava wastes in the environment.

The influence of alkaline copper quaternary (ACQ) preservative was studied relative to the bonding strength of Masson pine joints and the penetration of the adhesive into wood. Masson pine specimens treated with ACQ of three concentrations (0.1%, 0.5%, 1.0%) were bonded with aqueous polymer isocyanate (API) adhesive, and the shear strength, wood failure percentage, bondline thickness, average penetration depth (AP), and effective penetration depth (EP) of the wood joints were evaluated. The shear strength (6.34 to 6.85 MPa) and the wood failure percentage (87.0% to 87.8%) of the three series of treated joints were significantly lower than that of the untreated samples, while the treated specimens showed significantly larger bondline thickness (43.3 to 47.2 μm), smaller AP (30.6 to 35.8 μm), and smaller EP (24.7 to 25.7 μm) than the untreated specimens. The increase of ACQ concentration from 0.1% to 1.0% had no significant impact on the bonding strength and adhesive penetration parameters. The correlation between shear strength and penetration depths of treated joints was significant at the 0.01 level based on Pearson correlation analysis, while the coefficient of determination (R2) of the shear strength resulted from least squares regression analysis was 0.250 and 0.143 for AP and EP, respectively.

Batch experiments were conducted to evaluate the removal of Pb(II) ions from aqueous solutions using chemically and thermally activated cow dung (CTAC) ash and non-chemically but thermally activated cow dung (NTAC) ash under various experimental conditions. The optimum pH for the adsorption process using CTAC and NTAC was 5, while the optimum times using CTAC and NTAC were 240 and 180 min, respectively. Freundlich, Temkin, and Langmuir isotherm models were used to analyze the generated adsorption data. The Freundlich model had the highest coefficient of determination (R2) values that ranged from 0.989 to 0.999. The values of separation factor (RL) deduced from Langmuir isotherm were between 0 and 1 for both CTAC and NTAC ashes for the whole temperature range, which indicated favourable adsorption. Adsorption of the Pb(II) ions followed the pseudo-second-order kinetic model based on the R2 values that approached unity. Thermodynamic analyses revealed that the ΔH° values for CTAC and NTAC ashes were -8.69 and -11.39 kJ/mol, respectively, which indicated that ion adsorption was exothermic. Negative ∆S° values for the two adsorbents showed that the level of entropy was low at the solid/solvent interface during the adsorption process.

Mercury intrusion porosimetry (MIP) is an inexpensive and common technique to characterize porous structures like paper. One major limitation of MIP is the lack of information about the arrangement of pores in the structure, information that is particularly relevant for multilayer structures such as thickness-structured paper. In this article, results from Synchrotron X-ray 3D microtomography are combined with MIP data to provide in-depth and improved information about the structures.

Six different species of dry forest trees were collected, and their chemical compositions and thermal properties were determined. Three of the six species (Senegalia gaumeri, Havardia albicans, and Lysiloma latisiliquum) were chosen due to their high preference as firewood in local communities, while the remaining three species (Croton glabellus, Lonchocarpus yucatanensis, and Neomillspaughia emarginata) were chosen because of their abundance at the sampling site. The chemical compositions were consistent with the composition of tropical woods reported in previous literature, with an ash content of 4.8% to 6.8% and total extractible content in the range of 15.4% to 28.5%. The lignin content was in the range of 17.6% to 24.0%, while the range of holocellulose was 53.9% to 63.0%. The calculation of the calorific values was performed using the elemental analyses, and values ranging between 16.2 and 18.5 MJ/kg were obtained. The fuel value index (FVI) values for the samples indicated that S. gaumeri and L. yucatanensis were the best species for fuelwood given their high densities and relatively high calorific values. The kinetics of pyrolysis showed a higher level of reactivity for H. albicans and L. yucatanensis compared to the other species studied.

This paper studied the effect of thermal treatment (160 °C, 180 °C, and 210 °C), based on ThermoWood® principle, on the color and chemical properties of teak (Tectona grandis L. f.) and meranti (Shorea spp.) wood. The color of the wood was determined using the CIE L*a*b* system before and after the thermal treatment and was evaluated according to the total color change. The chemical changes were evaluated by wet chemical methods. The lightness of the wood was most affected during treatment. Meranti wood became darker (46.1%) compared with the teak wood (41.8%). The red-green and yellow-blue coordinates were higher in the teak wood, and their values decreased as the thermal treatment temperature increased in both wood species compared with untreated wood. The color change was higher in the meranti wood, and it increased steadily with increasing temperature. The extractives, cellulose, and lignin percentage contents increased in both wood species; however, the highest treatment temperature of 210 °C decreased the lignin in the meranti wood. The least stable component in both wood species was the hemicellulose. The hemicellulose content in the teak wood decreased by 67.7%, while it decreased by up to 80.5% in the meranti wood.

Biomass liquefaction is a major process used to obtain fuel additives, valuable chemicals, and high-quality activated carbon. In this work, three major biomass components (cellulose, hemicellulose, and lignin) and corn stalk were liquefied, and the corresponding liquefaction residue yields were 0.62%, 14.56%, 1.98%, and 1.29%, respectively, using polyhydric alcohols and acid catalysis under atmospheric pressure. The liquefaction residues from the corn stalk and biomass components were analyzed by thermogravimetric analysis, pyrolysis-gas chromatography/mass spectrometry, X-ray diffraction, and scanning electron microscopy. It was found that the corn stalk residues were mainly large molecules produced by interactions of some small molecules and incompletely degraded cellulose; condensation polymers generated from the reaction of degraded substances derived from lignin or hemicellulose; and insoluble components containing reactants from the degraded substances of the three major components and the insoluble substances generated by the liquefaction agents during the process.

Cellulosic henequen fibers were subjected to steam explosion and impregnated with polyethylene glycol (PEG) to improve fiber-matrix compatibility in polylactic acid (PLA) composites. Through Fourier-transform infrared spectroscopy (FTIR) it was shown that the hydroxyl, methyl, and ether functional groups were increased after the steam explosion treatment. Changes in the cellulose morphology caused by the steam explosion and impregnation with PEG were observed via scanning electron microscopy (SEM). Good adhesion of the treated cellulose and the PLA matrix was observed through improvement of the tensile strength and Young’s modulus of the PLA composite. The PEG impregnated into the fiber plasticized the PLA matrix and reduced the Tg from 59 °C to 52 °C. The increase in crystallinity confirmed the cellulose fibers induced nucleation of the PLA, which resulted in greater rigidity of the PLA composites.