Volume 10 Issue 4

To avoid undesired polymerization and maximize the selectivity of alkyl levulinate from the acid-catalyzed conversion of biomass-derived furfuryl alcohol, the effects of catalyst and reaction parameters on the formations of humin and alkyl levulinate were investigated. The results show that Amberlyst 15, of moderate acidic strength, was more favorable for the selective conversion of furfuryl alcohol to alkyl levulinate, and heteropolyacids of strong acidic strength tended to promote furfuryl alcohol polymerization. Compared with water as a reaction medium, alcohol significantly lowered humin formation and enhanced the yield of the resulting products. The formations of humin and alkyl levulinate were both favored at high catalyst loadings and reaction temperatures. An augmentation in initial furfuryl alcohol concentration caused an increase in humin formation and a decrease in alkyl levulinate yield. A high alkyl levulinate yield of up to 94% (100% furfuryl alcohol conversion) was achieved at 110 °C for 4 h with 5 g/L Amberlyst 15 catalyst and an initial furfuryl alcohol concentration of 0.1 mol/L. At this point, about 5% furfuryl alcohol was polymerized to form the humin, and its polymerization occurred mainly during the initial reaction stage.

In the present study, three ionic liquids, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), 1-allyl-3-methylimidazolium ([AMIM]Cl), and 1-ethyl-3-methylimidazolium chloride dimethyphosphate ([EMIM]DMP), were used to eliminate the brittleness of recycled fibers. The results showed that the pretreatments with ionic liquids were able to modify and improve the properties of recycled fibers even at high moisture contents. [EMIM]DMP gave better performance compared to [BMIM]Cl and [AMIM]Cl, which can tolerate higher moisture contents. The optimal conditions of EMIM]DMP pretreatment were moisture content of 65%, [EMIM]DMP dosage of 20 wt-%, 80 °C, and 60 min, for which a higher brittleness removal was obtained. The tensile index, bursting index, and tearing index of handsheets were increased by 32.4%, 57.0%, and 46.5%, respectively. Fiber quality was improved as demonstrated by fiber length, lowered fines content, and increased swellability. Such results imply that ionic liquids pretreatment can promote the swelling of recycled fibers and remove their brittleness.

A pellet mill is currently the most frequently used method for producing pellets using either a ring die or a flat die. In the densification process, a great amount of energy is required to avoid spring-back and to overcome the friction between the material and the channel surface of the die. However, extra energy is unnecessarily consumed because of friction between the roller and densified material and the pressure between the roller and die, where there are no opening channels. The aim of this work was to attempt to eliminate a portion of the frictional and compaction energy consumption based on an improved method of densification using a ring die. An upgraded pellet mill was designed and manufactured with rams on its roller. When the die and the roller rotate in a fixed transmission ratio, the rams precisely press raw material into opening channels on the die. Experimental tests on its feasibility were carried out. The results showed that the pellet mill, with this improvement, worked without wear on the surface of either the ring die or the roller; furthermore, the density and mechanical durability of pellets were the same as those produced using the traditional method.

Deinked pulp was pretreated using the 4-acetamido-2,2,6,6,- tetramethyl-pipelidine-1-oxyl radical (TEMPO)/NaBr/NaClO system and then bleached using hydrogen peroxide to achieve a medium pulp consistency. The effect of the amount of oxidant NaClO addition on the peroxide bleaching of deinked pulp was studied. The treated pulp was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The characterization of XRD and SEM showed that the treated pulp had a higher degree of crystallinity and more fibrillation than untreated pulp. Fiber quality analysis also revealed that the treated pulps had more fines and shorter fiber length than the untreated pulp. A handsheet test showed that the deinked pulps pretreated with the TEMPO system exhibited high tensile index values. The tensile index of the TEMPO pretreated pulp was 17% higher than that of the pulp bleached by hydrogen peroxide alone.

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.