Volume 8 Issue 4

Preprocessing of biomass at or near the growing site has considerable advantages over transporting to distant fermentation refineries equipped to process cellulosic material. The alkali-cellulase (Alkcell) process converts biomass to glucose using materials and methods that can be implemented at or near a growing site. This study has shown that the Alkcell process can be configured to run continuously. The use of carriers to contain the biomass allows continuous movement along a treatment train starting with alkali pretreatment and ending with glucose release. Conditions for pretreatment with NaOH, washing, and pH adjustment have been determined. Immersion of the carriers in a cellulase bath at optimal temperature and duration follows. The carriers are then submerged in a large volume of buffer at pH and temperature that allows release of glucose. Finally, the residual solids are returned to the start of the process to be mixed with fresh biomass and the treatment cycle is repeated. The glucose solution can be concentrated locally to reduce volume and enhance transportation savings. The local operation can be done at farms or near regional centers prior to being transported to distant existing conventional fermentation facilities.

Mesoporous activated carbons were prepared from coconut shells by the method of chemical activation with H3PO4. Effects of main influence factors on the yield and adsorption properties of activated carbon were studied via orthogonal experiments. Experimental results under the optimum conditions were as follows: the yield of the activated carbon was 36.90%; methylene blue adsorption was 21.5 mL/0.1 g; and the iodine number was 889.36 mg/g. The surface area of the activated carbon prepared was 891 m2/g, as determined by the BET method. Horvath-Kawazoe equations (H-K) and density functional theory (DFT) were introduced to analyze the porous structures of the activated carbon. It was shown that the activated carbon was mesoporous, with a total pore volume of 0.7233 mL/g, a micropore volume of 37.06%, a mesopore volume of 62.85%, and a macropore volume of 0.07%. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies demonstrated the results of the pore structure analysis.

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to investigate the primary pyrolysis product distribution of the pyrolysis of wood-plastic composites (WPCs) and the mutual effects of poplar wood (PW) and high-density polyethylene (HDPE). The PW, HDPE, and WPCs were pyrolysed at 475, 550, and 625 °C. The effect of temperature on the WPC pyrolysis products was examined. The comparison of the degradation composition results for HDPE, PW, and WPCs indicated that thermal degradation of WPCs comprised individual poplar wood and HDPE pyrolytic decompositions, and the pyrolytic products of PW and HDPE did not react with each other. The experimental results demonstrate that the pyrolytic product distribution of HDPE changed apparently in the presence of PW during pyrolysis. The PW decomposed at lower temperature during pyrolysis provided radicals, enhancing the scission of polymer chains to obtain more light paraffins. Further, the proposed pathway for the evolution of the main volatile organic products was probed. This study provides insights into the fundamental mechanisms of WPC pyrolysis and a basis for developing more descriptive models of WPC pyrolysis.

This study investigated the effects of various solvents on cypress liquefaction in the range of 180 to 300 °C. The solid residues and bio-oils obtained from cypress liquefaction were characterized to investigate the mechanism of the liquefaction process. Results obtained using FT-IR, sugar analysis, and elemental analysis showed that the solvent could affect both the formation of various compounds in the bio-oil and the product distribution during the cypress liquefaction process. Considering the bio-oil yield, the solvent efficiency in cypress liquefaction was as follows: water > methanol > ethanol. The decomposition velocities of cellulose, hemicelluloses, and lignin were different in the solvents, and hemicellulose decomposition preceded cellulose and lignin in all solvents. Water had the most pronounced effect on the higher heating value (HHV) of residues among the three tested solvents; the highest HHV was 26.3 MJ/Kg. This study suggests that characterization of products provides a promising approach for investigating the mechanism of solvent effects on biomass liquefaction.

The present paper aims to determine values of the modulus of elasticity (MOE) and modulus of rupture (MOR) of particleboards made from specially prepared particles from willow (Salix viminalis L.) and black locust (Robinia pseudoacacia L.) to enable formulation of an orthotropic material model for use in computer numerical simulations (FEM; finite element method). The mean densities of the panels were 600 and 660 kg·m^-3 for the willow and black locust, respectively. The MOE was used to test entire particleboards as well as their individual layers. The willow and black locust particleboards were compared with commercially available particleboards that met the requirements of the EN 312 standard. The modulus of rupture (MOR) of the particleboards was also determined according to the requirements of the EN 312 standard. The commercial particleboards showed the effects of different manufacturing directions, which resulted in changes in properties. No influence from manufacturing direction was found for the laboratory-made experimental panels. The impact of the thickness of the face layer of the specimens on MOE was also investigated. These tests indicated that the 2.1-mm sample showed no detectable distortive impact from the core layer. The tests confirmed the impact of manufacturing direction on the MOE of the commercial panels, which moreover was higher for the face layer. The highest MOE was found for the commercial panels, although the experimental panels met the requirements of the EN 312 standard, excluding the black locust at a mean density of 600 kg·m^-3.

Aluminum oxide nanoparticles were used as nanofillers in urea-formaldehyde (UF) resin and prepared for medium density fiberboards (MDF). The nanofillers composed weight percentage of the UF resin. The thermal and viscoelastic properties were studied using differential scanning calorimetry and dynamic mechanical analysis. The DH value of the UF resin showed an increase with increasing nanoparticle concentration. The core temperature during hot pressing increased with the addition of nanofillers. The formaldehyde emissions from MDF decreased with an increase in the concentration of nanofillers. The internal bonding strength and the modulus of rupture of boards were improved significantly after nanoparticle loading.

Effects of UV-light irradiation and water spray on the mechanical strength and surface characteristics of untreated and pretreated Scots pine sapwood samples were studied. The specimens were treated with parsley seed oil, pomegranate seed oil, linseed seed oil, nigella seed oil, canola oil, sesame seed oil, and soybean oil. The compositional changes and surface properties of the weathered samples were characterized by Fourier transform infrared (FTIR-ATR) spectroscopy and color and surface roughness measurements. The results showed that all vegetable oils provided lower color changes than the control group after 600 h of exposure in a weathering test cycle. The least color change was found on the Scots pine surface pretreated with pomegranate seed oil. The vegetable oil treatment retarded the surface lignin degradation during weathering, indicating that the surface roughness values of pine wood treated with vegetable oils decreased with irradiation over time compared with those of control samples. The effect of artificial weathering on mechanical strength was determined with a compression strength test. It was observed that the compression strength values of Scots pine samples treated with vegetable oils was higher than that of untreated samples after 600 h of weathering exposure.

To improve the interfacial compatibility between bamboo powder and polypropylene (PP), the effects of maleic anhydride-grafted polypropylene (MAPP) on the physico-mechanical properties and rheological behavior of 33 wt% bamboo powder/PP foamed composites were investigated. The results showed that the mechanical properties, water resistance, and surface wettability of MAPP-treated composites improved significantly, and the optimum content of MAPP was 9%. The density of 9% MAPP-treated composite was 0.845 g/cm3 and its specific bending and tensile and notched impact strengths increased by 22.9%, 29.6%, and 49.0%, respectively, and the water absorption decreased from 8.80% to 1.92%, compared to the untreated composite. The frequency sweep results indicated that both the modulus and complex viscosity of the 9% MAPP-treated composite reached minimum values, and the slope of the lgG’-lgf curve for the treated composite increased by 15.9% compared with that of the untreated analogue. ESEM results indicated that the MAPP-treated composite had better bamboo powder dispersion and better interfacial compatibility. FTIR and XPS analyses confirmed the esterification between anhydride groups of MAPP and hydroxyl groups of bamboo powder. XRD studies showed the degree of crystallinity for the MAPP-treated composite increased to 26.52%, compared to 21.05% for the untreated composite.

treated with a nano-ZnO solution at four treatment levels (0, 10,000, 20,000, and 40,000 ppm) using a modified dip method. Also, a thermal treatment was performed at 60 and 120 °C. After conditioning the samples, water absorption, volumetric swelling, water repellency effectiveness, and anti-shrink/anti-swell efficiency were determined within 24 h of soaking time. The results indicated that the nano-ZnO used for wood modification greatly improved dimensional stability and reduced the hygroscopicity of the wood. In addition, the Fourier-transform infrared spectroscopy (FTIR) analysis suggested a strong interaction between the nano-ZnO and the chemical components of wood. The heat treatment effectively improved the effects of nano-ZnO.

Thermal properties of wood and modified wood-based materials are important parameters that influence the manufacturing process and final industrial utilization. The aim of this work was to investigate three main thermal properties (thermal conductivity, thermal diffusivity, and specific heat capacity) of ammonia-treated compressed beech wood (Lignamon material) and natural beech wood (Fagus sylvatica).These properties were measured based on the quasi-stationary method developed at the Department of Wood Science at the Technical University in Zvolen. The influence of increased density (caused by ammonium treatment and compression) of four different types of Lignamon material on the thermal properties was discovered, and the results were compared with those from untreated beech wood. The results confirmed a dependency on the density of the material. With increasing Lignamon compression extent (increasing density value), the thermal conductivity increased and the thermal diffusivity decreased. The maximum value of thermal conductivity reached (0.26 W.m^-1.K^-1 at 1070 kg.m^-3) in the case of Lignamon 6k and (0.26 W.m^-1.K^-1 at 950 kg.m^-3) in the case of Lignamon 7n.