Research Articles

Different bleaching reagents have different efficiencies of removing chromophore groups from chemical pulps. The objective of this work was to evaluate the effect of different bleaching sequences on the removal of chromophore groups, especially carbonyls, which are suspected to cause brightness reversion. The bleaching sequences analyzed comprise the stages: chlorine dioxide, acid hydrolysis at high temperature, alkaline extraction with hydrogen peroxide, pressurized hydrogen peroxide, and hydrogen peroxide. After bleaching an oxygen-delignified eucalypt kraft pulp with these sequences, the pulps were analyzed for their final brightness, brightness reversion, and pulp viscosity; the bleached pulps were also analyzed using ultraviolet resonance Raman spectroscopy in the infrared region. The infrared analysis indicated that bleaching stages that used hydrogen peroxide, such as pressurized hydrogen peroxide or hydrogen peroxide, in the terminal position reduced the amount of carbonyl groups in the bleached pulp as measured by the absorption band intensity. This study observed that the inclusion of a hot acid hydrolysis stage in the bleach sequence improved the final brightness and brightness stability of the bleached eucalyptus pulp. The replacement of a chlorine dioxide brightening stage by a hydrogen peroxide stage at the end of a bleach sequence yielded higher pulp brightness, and less brightness reversion. The use of pressurized hydrogen peroxide with oxygen resulted in less brightness reversion.

Recently the accessibility of sago biomass has drawn considerable interest in research regarding the production of renewable energy. In this study, sago-derived biochar was evaluated and characterized as a solid fuel. Sago biochar was produced in an electric fluidized bed reactor at temperatures between 300 °C to 600 °C, with nitrogen flow rates of 50 mL/min to 100 mL/min for 10 to 30 min of process. The optimum condition to ensure the maximum biochar yield (47%) were obtained at 400 °C, 20 min of process and of 75 mL/min of nitrogen flow. The physicochemical properties of the final product were determined through thermogravimetric analysis (TGA), scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), and elemental analysis techniques. The higher heating value (HHV) of the material was remarkably improved by almost 13% via pyrolysis. The experimental results showed that sago biomass can be considered a suitable source of solid fuel, especially in the industrial and domestic sectors in Sarawak, Malaysia.

This paper explores the impact of daylit wooden environments on human perception and well-being. Several studies have shown that the use of wood in furniture, interior surfaces, and decoration helps create warm, bright, and pleasant ambiences, enhancing psychological well-being and comfort when compared to other materials. The main objective of this research was to assess the effects of different colors, finish, and ratio of wooden surfaces combinations on human perception. More specifically, participants compared simultaneously five different interior wooden scale models of room environments under the natural light of the northern hemisphere in terms of their appreciation, visual comfort, and well-being. The survey involved 80 participants with an exploratory questionnaire in order to compare and classify the different models. Conclusions showed a preference for clear, bright, and warm models for cognitive and small-scale tasks. Darker models in terms of reflectance and lighting ambiences were the least preferred, especially for women.

The effects of TiO2 (titanium dioxide) loading were evaluated relative to mechanical, thermal, and surface properties of the wood-plastic nanocomposites (WPNs). Pine wood flour, mixed with maleic anhydride polypropylene (MAPP), TiO2 nanoparticles (0 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%), and polypropylene, was compounded in a twin screw co-rotating extruder. The mass ratio of the wood flour to polypropylene (PP) was 50/50 (w/w) in all compounds. Test specimens were produced using injection molding machine from the pellets. Flexural and tensile properties, thermogravimetric analysis, surface roughness, wettability, and morphology of the manufactured nanocomposites were evaluated. Flexural and tensile properties of the wood-plastic nanocomposites increased with the increasing content of the TiO2. The surface roughness of the wood-plastic nanocomposites was reduced by increasing the content of TiO2. Increasing the loading of TiO2 increased the amount of residual ash and thermal stability.

To enhance effective wood utilization, knowledge of the anatomical features that impact its service behavior is indispensable. The anatomical features of branchwood and stemwood of Betula costata Trautv. from natural secondary forests in central (Muzhaling mountain) and northeast (Maoershan mountain) China were studied to provide adequate information to enhance their efficient utilization, especially branchwood, whose use could widen the raw material base of the timber industry. Microtomed sections were employed to determine the tissue dimensions and proportions. Analyses of variance were used to test the anatomical feature differences between the two different sites, between the stemwood and branchwood, and between the heartwood and sapwood. The results showed that B. costata wood is diffuse-porous with more but narrower vessels located in the branch than in the stem. The branchwood also had a significantly higher fiber proportion than the stemwood. The sapwood exhibited significantly longer fibers than the heartwood. B. costata from Maoershan had significantly longer fibers, lower fiber proportions, larger fiber lumen diameter, and higher vessel density than that from Muzhaling. The results suggested that B. costata branchwood from Maoershan is suitable for papermaking and glued plates, while stemwood can be used for light construction purposes.

Symbiotic bacteria in the termite gut system may play an important role in lignin degradation that can assist the subsequent saccharification process. Pseudocitrobacter anthropi MP-4, which is capable of degrading lignin components and rapidly growing on various lignin analogue dyes, was successfully screened from the gut of a wood-feeding termite Microtermes pakistanicus. Further decolorization tests with this strain showed that the strain MP-4 potentially produced some relevant extracellular enzymes to participate in lignin degradation. The removal rate of chemical oxygen demand by this strain was recorded as high as 52.1% when it was incubated in a mineral-salt medium with lignin as the sole carbon source. For the degrading process of MP-4 on lignin, it was proposed through a series of evaluations by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and pyrolysis gas chromatography/mass spectroscopy, that the lignin degradation mechanism of the strain MP-4 would primarily include the cleavage of various chemical linkages and the demethylation reactions. This resulted in a change in the S/G ratio and the disappearance of the biphenyl structure in the lignin components. Thus, these findings suggested that the strain MP-4 uniquely presented an attractive capability to deconstruct lignin components from biomass, which may be potentially valuable for a future industrial exploration.

The synergistic effect of hierarchically porous zeolites on the fire retardancy and fire toxicity of ammonium polyphosphate (APP) treated wood composites was studied in this work. Hierarchically porous 4A (H4A) zeolite and 4A zeolite were hydrothermally synthesized and characterized. Several groups of wood composites containing APP as fire retardant and H4A/4A zeolites as synergists were fabricated. Thermogravimetric (TG) results showed that H4A zeolite increased the char formation and enhanced the thermal stability of APP treated wood at higher temperature. Cone calorimetry test results suggested that H4A zeolite reduced the heat release rate (HRR) and decreased CO produce rate (COPR) of APP treated wood composites. Moreover, H4A also exhibited better smoke suppression than 4A zeolite when the APP content was small. These results demonstrated that H4A zeolites may be a promising synergistic component for improving the fire retardancy and reducing the fire toxicity of APP treated wood composites.

The goal of this study was to develop a lumber grade yield prediction model with a probability-based technique known as the Monte Carlo simulation. The data to develop the prediction model was taken from an existing lumber grade yield database developed from red oak logs sawn at the Appalachian region of the United States. Statistical input analysis techniques were used to fit the lumber grade yields to hypothesized probability distributions. Inverse cumulative probability function distributions were developed from the fitted probability distributions to simulate and predict lumber grade yields. The predicted gross revenue was compared with the actual gross revenue and against the gross revenue predicted by a multiple linear regression (MLR) model. The predicted gross revenue using the Monte Carlo simulation had a 0.88% absolute error compared with the actual gross revenue, while the predicted gross revenue from the MLR model had an absolute error of 3.31%. The higher prediction power of the Monte Carlo method was more effective when predicting lumber grade yields from individual log groups. The Monte Carlo model developed in this research can be easily implemented to quickly predict lumber grade yields or gross revenue to support procurement, log inventory management, production, planning, and marketing operations.

The wood sanding process entails a small reduction in the dimensions of the workpiece in the course of modifying its surface morphology, which affects the aesthetics and the subsequent application of a coating. However, sanding is costly, partly because it is performed empirically without standardization. Therefore, this study analyzed the influence of sandpaper factors on the behavior of wood surface roughness for Pinus elliottii. A complete factorial experiment was performed, varying two types of abrasives, aluminum oxide and silicon carbide, in three grit sizes (80, 100, and 120), and three sandpaper conditions (new, semi-new, and worn). The tests were performed using a flat sander with a pneumatic circuit and monitoring system for data acquisition, which were analyzed through multiple Tukey tests. The results were organized in a consultation table that compared the combination of factors analyzed, informing whether they produced roughness of the wood equal to or distinct from each other. The results showed that new aluminum oxide sandpapers with grit sizes of 80, 100, and 120 produced roughness of the wood different from each other, while the carbide did not. Therefore, there is no need to trade or buy silicon carbide sandpaper in these grit sizes.

The strengthening effect of basalt fiber-reinforced epoxy coatings was investigated with regard to their areal weight and position on the compression or tension side of plywood. Beach plywood was coated on one side with a basalt fiber-reinforced epoxy matrix. Two biaxial and one twilled fabric with areal weights of 170 g/m2, 210 g/m2, and 340 g/m2 respectively were used. The thickness of the plywood was 21 mm. The results showed the best reinforcing effect was obtained with the highest weight when mounted on the tension side of the parallel specimens. The bending strength of these specimens was improved by 15.7%. The perpendicular specimens were positively reinforced by the fiber-reinforced polymers on both the compression and tension sides. The tension reinforcement provided a higher deflection, which was further analyzed using digital image correlation. The evaluated data indicated significant displacement of the neutral axis. The impact strength of the parallel specimens was not improved by the reinforcement, but all of the reinforced perpendicular specimens were significantly strengthened.