Volume 9 Issue 1

This study evaluated the effect of microwave radiation on the fluid permeability and compression strength parallel to the grain of beech false heartwood. European beech (Fagus sylvatica L.) was selected, and samples of false heartwood with dimensions of 30×20×20 mm³ were used. The microwave treatment was carried out in a laboratory device at a frequency of 2.45 GHz. The testing samples were divided into three groups (untreated, treated at 20-s intervals, and treated at 30-s intervals). The permeability was measured in the axial direction using distilled water. The coefficient of specific permeability was calculated using Darcy’s law. The results showed that the coefficient of specific permeability increased by up to 159% in comparison with untreated samples. The compression strength parallel to the grain decreased by up to 15%.

The reinforcement potential of novel nanocellulose-based scaffolding reinforcements composed of microfibrils 5 to 50 nm in diameter and several microns in length was investigated. The cellulose nanofibril reinforcement was used to produce a three-dimensional scaffolding. A hybrid two-step approach using vacuum pressure and hot pressing was used to integrate the nanocellulose reinforcements in a liquid molding process with an epoxy resin to manufacture composites containing fiber volume contents ranging from 0.6% to 7.5%. The mechanical properties were studied using three-point bending. The Shore-D hardness test and differential scanning calorimetry (DSC) were used to investigate the curing response and its relation to the mechanical properties. Dynamic mechanical analysis (DMA) with a three-point bend setup was used to investigate the viscoelastic behavior of the nanocellulose composite samples at various temperatures and dynamic loadings. The results using the proposed liquid resin manufacturing method for processing the nanocellulose composites showed an increased modulus and a lower strain-to-failure compared to neat resin. Dynamic testing showed a trend of lower tan delta peaks and a reduction in the glass transition temperature with the addition of nanocellulose reinforcement.

The production of six regionally important cellulosic biomass feedstocks, including pine, eucalyptus, unmanaged hardwoods, forest residues, switchgrass, and sweet sorghum, was analyzed using consistent life cycle methodologies and system boundaries to identify feedstocks with the lowest cost and environmental impacts. Supply chain analysis was performed for each feedstock, calculating costs and supply requirements for the production of 453,592 dry tonnes of biomass per year. Cradle-to-gate environmental impacts from these modeled supply systems were quantified for nine mid-point indicators using SimaPro 7.2 LCA software. Conversion of grassland to managed forest for bioenergy resulted in large reductions in GHG emissions due to carbon uptake associated with direct land use change. By contrast, converting forests to cropland resulted in large increases in GHG emissions. Production of forest-based feedstocks for biofuels resulted in lower delivered cost, lower greenhouse gas (GHG) emissions, and lower overall environmental impacts than the agricultural feedstocks studied. Forest residues had the lowest environmental impact and delivered cost per dry tonne. Using forest-based biomass feedstocks instead of agricultural feedstocks would result in lower cradle-to-gate environmental impacts and delivered biomass costs for biofuel production in the southern U.S.

The main pentosan components of sugarcane bagasse, which can be subjected to alkaline hydrolysis, are xylose, arabinose, glucose, and galactose. The pentosan reaction mechanism was considered for alkali-treated bagasse with variation of temperature and time. The kinetics of pentosan degradation were studied concurrently at temperatures of 50 °C, 70 °C, and 90 °C, with a solid-liquid mass ratio of 1:15, a stirring speed of 500 revolutions/min, and different holding times for bagasse alkali pre-extraction. With respect to residual pentosan content and the losses of raw material, the hydrolysis rates of alkali pre-extraction and pentosan degradation reactions of bagasse all followed pseudo-first-order kinetic models. Finally, the main degradation activation energy was determined to be 20.86 KJ/mol, and the residual degradation activation energy was 28.75 KJ/mol according to the Arrhenius equation.

This study was conducted to enhance the physical, mechanical, and thermal properties of the inner part of the oil palm trunk (IP-OPT) impregnated with oil palm shell (OPS) nanoparticles at various concentrations (0, 1, 3, 5, and 10%) and phenol formaldehyde (PF) resin. The PF concentration was 15% (w/w basis) throughout the study. The physical, mechanical, and thermal properties of the OPS nanoparticle-impregnated IP-OPT lumber were analyzed according to various standards. It was found that IP-OPT gained a significant percentage of weight (up to 35.3%) due to the treatment, leading to a density increase from 0.42 to 0.89 g/cm³. The water absorption was reduced by up to 24%, which reduced the swelling coefficient, and thus, the anti-swelling efficiency was increased significantly. The tensile and flexural strengths increased from 9.77 to 19.64 MPa and from 14.46 to 38.55 MPa, respectively. The tensile and flexural moduli increased from 2.67 to 3.51 GPa and from 4.35 to 4.95 GPa, respectively, while the elongation at break decreased from 7.83 to 6.42%. The impact strength also increased significantly, from 6.90 to 15.85 kJ/m². In addition, the thermal stability of IP-OPT was improved by the impregnation of OPS nanoparticles. Thus, it can be concluded that the impregnation of IP-OPT with OPS nanoparticles might be a good treatment process for enhancing the properties of the IP-OPT.

Five polyamine fixing agents with different molecular weights but slightly different charge densities were used to treat a deinked pulp. Their efficacy in controlling colloidal substances (CS) in the pulp was measured using focused beam reflectance measurements (FBRM). The objective was to determine if the colloidal substances were affected by the fixing agents by a “colloidal fixation” mechanism, i.e., colloidal particles being fixed onto pulp fiber in an un-agglomerated, single-particle state, or a “colloidal agglomeration” one, i.e., colloidal particles being coagulated by fixing agents into bigger agglomerates. The results showed that colloidal fixation does take place, especially for the polyamine with the smallest molecular weight. Among the five polyamines, it was found that higher molecular weights tended to result in more extensive colloidal agglomeration, but the effect of charge density was almost insignificant. Because it is efficient in differentiating between these two fixation mechanisms, FBRM is a powerful tool in screening different fixing agents.

Seven varieties of vine prunings (Vitis vinifera L.)grown under Riyadh conditions were considered as renewable sources for fuelwood. Significant effects (P<0.01) were found for total extractives, benzene-ethanol extractives, cellulose, hemicellulose, lignin, cold water solubility, and hot water solubility among the seven vine varieties. Highly significant positive correlations (P<0.01) were observed between the higher heating value (HHV) and benzene-ethanol extractives (r=0.74) and lignin content (r=0.94). Additionally, elemental composition (C, H, N, O, and S) exhibited a significant effect on HV (P<0.01) and ash content of the seven vine varieties. There were highly significant positive correlations (P<0.01) between the HV and C (r=0.96) and H (r=0.93). Ash content showed a highly significant effect (P<0.01) on HV with a negative coefficient (r=-0.93). The heating value of vine prunings ranged from 18.74 to 19.19 MJ/kg, i.e. higher than some well-known biomass fuels. The results suggested that the vine prunings could be suitable as a source for energy production in Saudi Arabia.

Starch of moso bamboo mainly exists in the elongated parenchyma cells, and it is difficult for amylase to enter moso bamboo and dissolve the starch. Therefore, the mould resistance capability of moso bamboo’s products cannot meet the need for bamboo to resist fungal decay. In this experiment, moso bamboo blocks were first treated at six levels of pressure and for six different treatment durations. The results showed that reducing sugar content was decreased dramatically from 0.92 mg/L to 0.19 mg/L and the starch content decreased from 1.18% to 0.96% when the pressure was increased from 0 psi to 100 psi. Regression analysis showed that the effects of an individual amylase reaction and individual pressure treatment on the starch or reducing sugar content were significant with a high correlation coefficient. Three traditional types of moso bamboo moulds (Aspergillus niger, Penicillium citrinum, and Trichoderma viride) were then used for mould resistance testing. The results revealed that the mould resistance capability of moso bamboo blocks could be greatly improved by the combined effect of enzyme activity and pressure treatment. Mould resistance was enhanced by increasing the pressure or prolonging the treatment time. This research could provide a new method for the protection of bamboo from mould attack.

The effects of alkaline pretreatment with NaOH, KOH, Ca(OH)2, and NaOCl at varying temperatures and concentrations on the production of sugars, changes in the morphological structure, and the chemical composition of rice straw were evaluated. Enzymatic saccharification of 2% (w/v) KOH-treated rice straw with autoclaving at 121 °C, 15 psi, 20 min, gave a maximum yield of 59.90 g/L of reducing sugars, which was slightly higher than that of NaOH (55.48 g/L) with the same conditions. Chemical composition analysis of the rice straw showed that the cellulose content was increased to 71% and 66% after pretreatments with NaOH and KOH, respectively. Fourier Transform Infrared (FTIR) spectroscopy revealed that solubilization and removal of the lignin component also took place. The scanning electron microscope (SEM) analysis showed a marked change in the morphological structure of the treated rice straw compared to the untreated rice straw. These results suggested that pretreatment of rice straw with either 2% (w/v) NaOH or KOH at high temperature could be a promising pretreatment method for sugars production.

The main objective of this study was to evaluate the potential of sodium percarbonate and sodium perborate utilization during repulping of old news and magazine paper mixture. A series of experiments were performed to determine the effects of bleaching agents on ISO brightness and ink removal efficiency of pulp after flotation deinking. Conventionally, with other parameters are constant, the ISO brightness of pulp was increased from 45.24% to 54.10% and ink elimination ratio at 950 nm of pulp was increased to 69.12% with 1% sodium hydroxide and 1% (as active oxygen content) hydrogen peroxide usage. However, when sodium percarbonate was utilized instead of hydrogen peroxide (as 1% active oxygen content) without alkaline addition, the ISO brightness of the pulp was increased to 55.00%. Also, unlike the other bleaching agents, a favorable effect of sodium percarbonate on ink detachment was observed. The ink elimination ratio of floated pulp was increased to 74.31% with 1% (active oxygen) sodium percarbonate addition without alkaline usage. There were no additive effects of sodium perborate usage on brightness, and ERIC value of pulp could be determined. In this respect, sodium percarbonate utilization without sodium hydroxide addition was proposed for effective repulping, deinking, and prebleaching of waste papers, in a similar manner to the use of hydrogen peroxide.