Research Articles

The combustion of effluent biogas from a palm oil mill is not feasible on a large scale because of its low calorific value (LCV). Therefore, the captured biogas is usually flared because of a lack of appropriate combustion technology. However, such biogas could be an excellent source of energy for combined heat and power (CHP) generation in palm oil mills. In this paper, the feasibility of using biogas from palm oil mills in flameless combustion systems is investigated. In computational fluid dynamic (CFD) modeling, a two-step reaction scheme is employed to simulate the eddy dissipation method (EDM). In such biogas flameless combustion, the temperature inside the chamber is uniform and hot spots are eliminated. The peak of the non-luminous flame volume and the maximum temperature uniformity occur under stoichiometric conditions when the concentration of oxygen in the oxidizer is 7%. In these conditions, as the concentration of oxygen in the oxidizer increases, the efficiency of palm oil mill effluent biogas flameless combustion increases. The maximum efficiency (around 61% in the experiment) is achieved when the percentage of oxygen in the oxidizer is 7%.

The effects of hydrothermal pre-treatment on the color of silver birch veneer were determined. Spectrophotometric and chemical analyses of the veneer by means of extraction were conducted to determine the detailed chemical characteristics of the veneers. Results from spectrophotometric analysis revealed a significant increase in lightness (L*) and a decrease in yellowness (b*) in the veneer produced from a log soaked at 70 °C in short-term. Conversely, the effect of long-term storage resulted in a significant reduction in L* and an increase in b*. Chemical analyses of the veneer extract identified a moderate negative correlation between soluble proanthocyanidins content and treatment temperature. A higher amount of wood extractives, such as lipophilic extractives, free monosaccharides, and other organic substances, were obtained from wood material soaked at 70 °C than at 20 °C, which was most likely due to moderate chemical changes during treatment. Comparison of the results between dried veneers and wet veneers from the water extraction study revealed that the dried veneers had higher amounts of lipophilic matter and less water-soluble organic matter than the wet veneers. Other aspects of the loss of soluble proanthocyanidins in the birch veneer during plywood manufacturing are discussed.

A low-cost sepiolite (SEP) was used to replace wheat flour (WF) as a filler applied to melamine-urea-formaldehyde (MUF) resin. Three-ply plywood was fabricated with different SEP/WF formulations, and its wet shear strength and formaldehyde emission were tested. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to explain why the performance of the plywood improved. Results showed that the wet shear strength of the plywood increased with the addition of SEP in the filler. When using SEP to replace 80% of the WF, the wet shear strength was improved by 27.8%, which was attributed to the penetration network with hydrogen bonds formed by SEP and MUF resin. Using SEP in the filler formulation created a smoother, denser, and more regular cross-section to prevent moisture intrusion, which improved the water resistance of the adhesive and thus further increased the wet shear strength of the resultant plywood. The tunnel structure of SEP could accelerate the free formaldehyde emission of the plywood. As a result, using SEP replace 80% WF as a filler, the formaldehyde emission of the plywood was reduced by 7.8% due to the tunnel release effect.

The suitability of saturated salt solutions as a dispersive agent for preparing microfibrillated cellulose (MFC) from bamboo processing residue through ultrasonication was evaluated. The effect of pure water and KCl solution on the rheological behavior and morphologies of prepared MFC were compared. The results show that the viscosity of MFC suspension dispersed in KCl solution decreases by several orders of magnitude compared to the water counterpart. SEM images demonstrate that MFCs with comparable quality can be prepared using either pure water or KCl solution as a dispersive agent. A high concentration of bamboo processing residue (~2 wt.%) dispersed in salt solutions was found to possess comparable viscosity with a low concentration of MFC suspension (~0.5 wt.%) dispersed in water. This indicates that the application of salt solutions as dispersive agents in ultrasonication has great potential to improve the productivity of MFC prepared from plant materials.

The sawmilling sector is the backbone of the Malaysian wood-based industry. Sawn timber is used extensively for further manufacturing of secondary wood-based products. The conversion of saw-logs into sawn timber releases several gases into the atmosphere, and these may contribute to environmental burdens as well as environmental impacts. Thus, this study aims to determine the environmental performance from gate-to-gate in the sawmilling industry using the life cycle assessment technique. Data pertaining to the saw-logs and energy consumption was calculated, and the environmental performance was assessed. The study focused on two different size sawmills and two tropical hardwood species. The findings concluded that several types of gases namely, CO2, CH4, NOx, N2O, SO2, and CO were discharged to the environment as a result of sawmilling processes. The discharge of these gases impacted the environment in the form of global warming, acidification, human toxicity, eutrophication, and photo-oxidant formation potentials.

Dimensional changes in both non-densified and densified, thin, wooden components and layered materials after external pressing forces were released were evaluated in this work. Densification was carried out using a cold process on a semi-automatic hydraulic pressing machine. The specimens’ dimensional stabilities, focusing mainly on their residual plastic deformations, were monitored. The impacts of several factors, such as wood species, material thickness, densification degree, and their combinations, were analyzed. Results showed that, with increased degree of densification, the relative plastic deformations (pressing degree) usually decreased. With regard to the compositions explored, the best combination was a top poplar layer densified by 10% plus a bottom beech layer densified by 20%. The impacts of each of the factors on the pressing degree values proved to be significant; the least significant was the bottom beech layer thickness and degree of densification. The greatest practical benefits can be obtained using the recommended combinations of composite layers.

With the aim of identifying and exploiting the mycological resources available in the Mexican Sierra Madre Oriental, the lignocellulolytic and pectinolytic potential of autochthonous fungi were evaluated in the present work. A solid media selection system was established in which 74 isolated strains were tested and compared to six international reference strains. The macrofungi Xylaria sp CS121, Inonotus sp CU7, Basidiomycete CH32, Basidiomycete CH23, Xylaria poitei, and Trametes maxima CU1 showed the highest cellulolytic and pectinolytic potential. The greatest lignolytic capability was exhibited by T. maxima CU1 and Pycnoporus sanguineus CS43. Under stirred submerged culture, T. maxima CU1 (cellulases, cellobiose dehydrogenase, manganese peroxidase (MnP), and laccase, with 200, 359, 51, and 267 U/L, respectively) and Xylaria sp CS121 (198 U/L of xylanases) were the highest enzymatic producers. Under stationary conditions, the best producers were Inonotus sp CU7 for cellulases, P. sanguineus CS43 for cellobiose dehydrogenase and laccase, and T. maxima CU1 for xylanases and MnP (242, 467, 35, 165, and 31 U/L, respectively). These results demonstrate the efficiency of enzymatic profiling as a tool for enzyme discovery with Mexican native fungi.

The potential usage of Pinus wood residues in cement-wood composites and the behavior of CaCl2∙2H2O, used as an additive were assessed in this work. In order to improve the interaction between the cement-wood composites, CaCl2∙2H2O and 12 different pre-treatment types were tested. Pre-treatments involved extractions in cold and hot water, NaOH solutions, and several Ca(OH)2 concentrations for different times. An evaluation of the mechanical features (compressive strength and tensile resistances) of composites was also performed using 50 mm cylindrical samples. The interaction of the composites was analyzed using Bragg sensors in optical fibers. Pinus residues were tested having particle size of 4.8 mm and a CaCl2∙2H2O content between 0% and 8%. The highest compressive strength was observed for the production of composites with 4.5% CaCl2∙2H2O and the hot and cold water pre-treatment. Conversely, for tensile strength, the highest performance occurred when NaOH was used as a pre-treatment. The technology for determining the temperature of composites using Bragg sensors in optical fibers was judged to be efficient.

Regenerated cellulose film with better mechanical properties was successfully produced by introducing aldehyde crosslinker during the regeneration process. The cellulose source material was derived from kenaf core powder and dissolved in LiOH/urea solvent at −13 °C to form a cellulose solution. The cellulose solution was cast and coagulated in a crosslinker bath at different percentages of glutaraldehyde (GA) and glyoxal (GX) to form a regenerated cellulose film. According to Fourier transform infrared spectroscopy (FTIR) spectra, the hydroxyl group of the cellulose was reduced, reducing the percentage of swelling as the percentage of crosslinker was increased. X-ray diffraction (XRD) patterns showed that the crystallinity index of the crosslinked film was decreased. The pore size of the films decreased as the percentage of crosslinker was increased, resulting in decreased film transparency. The pore volume and percentage of swelling in water of the films also increased with decreases in the pore size as the percentage of crosslinker was increased. The tensile strengths of the GA- and GX-crosslinked films increased by 20 and 15% with the addition of 20% of each crosslinker, respectively.

Using response surface method to determine the optimal technological conditions of biomass-based precursor preparation, magnetic Fe3O4 particles were loaded on the surface and internal channel of biomass-based precursor to prepare a magnetic biomass-based solid acid catalyst using the sol-gel method. To investigate the performance of the magnetic catalyst, it was used to hydrolyze cellulose into reducing sugar, whose structure was characterized by infrared spectrum analysis. The optimum process conditions of biomass-based precursor preparation was obtained by quadratic regression model as a carbonization temperature of 549 °C, carbonization time of 13 h, sulfonating temperature of 121 °C, and sulfonating time of 6 h. Using the biomass-based solid acid catalyst to hydrolyze cellulose, a reducing sugar yield of 57.36% was obtained. Compared with the traditional solid acid catalysts, the total reducing sugar yield was increased by 65%. The infrared spectrum analysis showed that magnetic Fe3O4 particles were combined successfully with biomass-based precursor. This magnetic biomass-based solid acid catalyst has a carbon structure layer of vermicular disorder and possesses high stability.