Research Articles

The aim of this work was to investigate the influence of sample preparation including variation in moisture content and particle size on the accuracy of near infrared (NIR) spectroscopy models developed to predict Klason lignin, total lignin, and holocellulose in wood. Seventy-five samples of sawdust obtained from a eucalyptus plantation were divided into aliquots and submitted to three different treatments: traditional (TRAD), large particle dried at room temperature (LPRT), and large particle oven-dried (LPOD). The influence of sample preparation method on models’ accuracy was compared by statistical analysis. Overall, grinding to a larger particle size and drying at room temperature (treatment LPRT) did not decrease the accuracy of the prediction models when compared to the TRAD sample preparation method. These findings were more evident for Klason lignin and holocellulose. This is relevant because resources used for sample preparation (i.e. grinding and drying) can be minimized, which is expected to reduce the costs associated with analysis of wood properties by NIR.

In the authors’ previous studies, a bleaching process based on continuous chemical supplementation (CCS) was proposed to improve the effectiveness of peroxide bleaching of chemi-thermomechanical pulp (CTMP). In this study, the kinetic model of the CCS process of peroxide bleaching was applied to poplar CTMP to explore how the bleaching rate was affected. The model was based on the rate of chromophore elimination characterized by the brightness gains of bleached pulp. The reaction rate of chromophore destruction proceeded via a rapid initial phase followed by a slow phase. The equation of reaction rate was confirmed. The value of reaction order was -3.62, and the activation energy was 288.8 kJ/mol. The developed kinetic model was a good fit for the experimental results.

Furniture must be designed to suit the intended use. Producers need to guarantee its quality and stiffness. During external loading, there are internal forces that can be transmitted and may result in a failure. This article examines the dowel joint, which is one of the most popular furniture joints. It discusses the effects of selected parameters, such as type of loading (tension and pressure), the size of the dowel (one-half or one-third of the joined parts), wood species [beech (Fagus sylvatica L.) and spruce (Picea abies L.)], and the adhesives type (polyvinyl acetate and polyurethane), on the joint stiffness. The effect of the annual rings was also monitored; however it was not determined as significant. Based on the results, the dowel joint is recommended with greater diameters and while using PVAc gluing. Article also deals with test simulation in virtual environment using the programme Solidworks.

Biogas projects are rapidly expanding in China, but there is insufficient cropland to degrade these biogas residues. Mushroom cultivation has been used to degrade various agricultural wastes. In this study, to screen the feasibility of utilizing biogas residues as potential substrates for the cultivation of Pleurotus ostreatus, seven different concentrations (0 to 60%) of biogas residue mixed with cottonseed hull, wheat bran, and lime were used to cultivate P. ostreatus. The mycelial growth rate, mycelial colonization time, yield, biological efficiency, chemical compositions, and content of four heavy metals, Cd (cadmium), Pb (lead), Hg (mercury), and As (arsenic), were analyzed. The results showed that 10 to 30% of biogas residue mixed in the substrates induced the growth of P. ostreatus mycelia faster than the others. A lower percentage (10 to 20%) of biogas residue added to the substrates is beneficial to the production and nutrient components of P. ostreatus, and the fruiting bodies produced on biogas residue-containing substrates conform to the safety standards for edible mushrooms. Although the total harvest is not significantly increased when biogas residue is added, the utilization of cheap biogas residues can conceivably reduce the practical cost and benefit the environment.

Biomass chars (bio-chars) prepared under two pyrolysis modes and with four particle size ranges were investigated. The pyrolysis modes included isothermal pyrolysis and non-isothermal pyrolysis with three heating rates (5 °C/min, 10 °C/min, and 15 °C/min). The particle size ranges were 58-75 μm, 75-106 μm, 106-150 μm, and 150-270 μm. The pyrolysis characteristics, pore structures, surface morphologies, and functional groups of the bio-chars were characterized by TGA, specific surface area and porosity analyses, SEM, and FTIR. The mercury adsorption was further explored by the adsorption kinetics. The results established the optimum pyrolysis conditions for mercury adsorption: pyrolysis temperature of 600 °C, heating rate of 10 °C/min, and particle size of 58-75 μm. In addition, the mercury adsorption processes were affected by both physical adsorption and chemical adsorption. Furthermore, the rate constants of the pseudo-first-order and pseudo-second-order models gradually increased with decreasing particle size.

An in-situ observation on the morphological behavior of bamboo’s fiber-foam composite structure under flexural stress was conducted, and the respective contribution of parenchymatous tissues and sclerenchyma fibers to the flexural ductility of bamboo was evaluated. Fibers or parenchymatous cells at the bottom suffered tensile stress during bending process, where initial microcracks occurred. The results suggested that the bottom parenchymatous tissues experienced a perforative tear along the loading direction, while fibers continued to stretch until several fibrous tensile failure cracks were observed. The subsequent crack growth mode was similar to that of the horizontal crack transmission that began when it reached fibers or somewhere between fibers, until another weak load-bearing point appeared, and then it expanded up through parenchymatous tissues. As a whole, the crack acted ladder-like in its growth, and the propagation paths were not restricted to a coherent one. Images of the morphological changes of the upper parenchymatous tissues and sclerenchyma fibers, which suffered compressive stress during bending process, indicated that parenchymatous tissues and sclerenchyma fibers made different contributions to the flexural ductility of bamboo. Sclerenchyma fibers supplied deformation resistance for bamboo’s macroscopic deformation, while parenchymatous tissues offered deformation space due to the variation of cellular morphology and location.

The catalytic microwave-assisted pyrolysis of pine sawdust using SiC and Ni modified HZSM-5 as microwave absorbent and catalyst for high quality bio-oil production was investigated. The Ni modified HZSM-5 catalyst was successfully prepared through the co-precipitation method and further characterized by X-ray diffraction (XRD) and surface area and pore size analyses. The product yield results showed that Ni modified HZSM-5 catalyst decreased the bio-oil yield and increased the gas yield. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the bio-oil mainly contained alcohols, aldehydes, ketones, carboxylic acids, furans, and phenolics. The Ni modified HZSM-5 catalyst dramatically decreased the carboxylic acids and ketones content, while it remarkably increased phenolics, especially the phenol content. The physical property analysis showed that the bio-oil with the Ni modified HZSM-5 catalyst had a higher calorific value. Therefore, under microwave-assisted pyrolysis conditions, Ni modified HZSM-5 catalyst had a remarkable effect for improving the quality of bio-oil.

Proper valorization of the sawing wastes in industrial sawmills is a permanent issue with strong economic and environmental stakes. Most industrial sawmills are equipped with chipper-canter heads reducing the outer part of the logs into chips used in the pulp and paper industry. Optimization in canter use would increase the acceptable proportion of exploitable chips for this industry. With chipper-canters, the cutting direction varies along the cut. This study investigates the impact of the angle formed between the cutting direction and the grain direction on the required cutting force and the chips’ geometry. Orthogonal cutting is conducted to simulate the chipper-canter machining operation on green beech. To lower the cutting forces when machining, aiming for a cutting direction as parallel as possible to the wood fiber is necessary. However, if this angle is too low, the chips’ generated geometries prevent them from a proper valorization of this resource. A compromise with grain direction between 50° to 70° both limits the cutting forces and improves the steadiness of the chip fragmentation.

The use of heat treatment to modify wood using different treatment heat transfer media, such as nitrogen, vegetable oil, steam, and vacuum, is preferable in many respects to other methods that use chemical treatments. However, the results of the heat treatment differ based on the heat transfer media that are used. In this study, the thermal modification of black pine wood in vacuum, nitrogen, and air atmospheres was studied. The heat treatments were conducted at temperatures of 180 °C, 200 °C, and 220 °C. After the heat treatments, the density, mass loss, modulus of rupture, modulus of elasticity, and impact of bending of heat-treated black pine wood were determined. The results indicated that the density, modulus of rupture, and impact of bending decreased as the temperature increased. In addition, the greatest decrease in the mechanical properties of the wood occurred in the test samples that were treated in air. The vacuum atmosphere was least harmful to the mechanical properties of the wood, and the differences in the mechanical properties of the wood that were heat treated in vacuum and nitrogen were unnoticeable.

A polyol-based ester was synthesized from biomass-derived bio-oil for application as a biolubricant. The bio-ester is biodegradable, non-toxic, and does not require mineral oil usage. Levulinic acid (LA), a major component obtained from bio-oil, was used for the catalytic esterification with two types of polyols, i.e., trimethylolpropane (TMP) and pentaerythritol (PE), in the presence of alumina-supported Cu(II), Co(II), and Fe(II) complexes as catalysts. Alumina-supported Cu(II), Co(II), and Fe(II) complexes [Cu(Tyr)(GA)]Cl-alumina, [Co(Tyr)(Amp)]Cl-alumina, and [Fe(Tyr)(Amp)]Cl-alumina were synthesized by the reaction of ligands [L-tyrosine (Tyr), Gallic acid (GA), and 2-aminopyridine (Amp)] with metal chloride salts. The catalysts were characterized by elemental analyses (CHN), magnetic susceptibility, Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis/differential thermal analysis (TGA/DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) techniques. Catalytic performances of the synthesized complexes were investigated via esterification of levulinic acid with trimethylolpropane and pentaerythritol. In addition, the two best catalysts, [Cu(Tyr)(GA)]Cl and [Co(Tyr)(Amp)]Cl-alumina, were further employed for the in situ hydrogenation of levulinate esters at 120 °C to 130 °C and 7 bar to 8 bar H2 pressure for upgrading in a specially designed reactor. The alumina-supported catalysts were active, reusable, and exhibited their efficiency as heterogeneous catalysts for esterification and hydrogenation reactions for synthesizing ester-based oils.