Volume 9 Issue 4

The dynamic wettability of adhesive on sanded and aged wood surfaces was measured using the sessile drop method. Four different models were used to evaluate and compare the wetting process. It was shown that the wettability of freshly sanded wood and aged wood both decreased compared to the control wood. There was no evidence of change in wettability with increasing grit number. Aging reduced the wettability of the wood surface. The coefficients of determination (R2) for all four models were over 90%, and that of the Modified model was 99%. The models can be used to accurately describe the adhesive wetting process. The wettability of water and adhesive on the fresh surface were different, and the wettability of the adhesive increased as grit number increased. On the contrary, the wettability of water decreased as grit number increased, and the same trend was found for the water and the adhesive on the aged wood surface. Advantages and disadvantages were found for each model, but the Modified model needs to be verified by additional experiments.

Pulp and paper mills are a major source of pollution, generating huge amounts of intensely colored effluent that goes to the receiving end of a wastewater treatment plant. The biochemical oxygen demand test (BOD5) relies heavily on the microorganism metabolic capability added to the test as seeding material. The seeding material in the testing is obtained from sewage sampling or from commercial sources. Specific organic pollutants that are present in paper and pulp mill effluent can only be degraded by specific microbes; therefore, common sewage or synthetic seed may lead to erroneous BOD5 estimations. In this study, specific microbial species were selected to evaluate their degradation efficiency, both individually and in combination. The microorganisms selected in the formulated seed exhibit BOD5 in a reproducible and synergistic manner. The formulation of this specific microbial consortium can be used to develop bioremediation strategies.

Studies concerning the production of medium-density fiberboard (MDF) with kenaf as an alternative fibrous material were carried out as an attempt to provide a sustainable and viable source for this lignocellulosic product. This work sought to evaluate the influence of fiber properties (including fiber length, width, wall thickness, and lumen diameter that affect aspect and flexibility ratios) on specific gas permeability in medium-density fiberboard (MDF) made from kenaf bast and core fibers, respectively. Results showed that MDF panels produced from kenaf core had significantly lower permeability than those produced from kenaf bast. This lower permeability was primarily related to the higher flexibility ratio of kenaf core fibers, which provided more surface connection area between fibers, resulting in higher integration among fibers. Lower ash and extractive contents of the core section also improved the efficiency of resin and the connection of fibers to each other; eventually lower permeability was observed in panels made from kenaf core. A high correlation was found between gas permeability and water absorption.

Prosopis juliflora is a drought-resistant evergreen spiny tree that grows in semi-arid and arid tracts of tropical and sub-tropical regions of the world. Dry pods of P. juliflora are a rich source of carbon (40% total sugar) and nitrogen (15% of total nitrogen) and so can be considered as a good substrate for the microbial growth. The present study was mainly focused on the utilization of these pods for the production and statistical optimization of oxytetracycline (OTC) from Streptomyces rimosus NCIM 2213 under SSF. The spectral characterization and chemical color reactions of purified OTC by UV, FTIR, 1H NMR, 13C NMR, and HPLC revealed that the structure was homologous to a standard sample. A central composite design with 26 trails yielded the following critical values of supplements to be added to the dry pods: maltose (0.125 g/gds), Inoculum size (0.617 mL/gds), CaCO3 (0.0026 g/gds), and moisture content (74.87%) with the maximum OTC yield 5.02 mg/gds.

As the main raw material for fiberboard, the hygroscopicity of wood fibers is of great concern. In this study, three alkoxysilanes with different chain lengths—methyl trimethoxy silane (MTMS), octyl trimethoxy silane (OTMS), and dodecyl trimethoxysilane (DTMS)—were used respectively to treat wood fibers to reduce their hygroscopicity and surface hydrophilicity. After alkoyxilane properties were evaluated, the chemical structures, surface groups, and morphology and distribution of alkoxysilanes within modified wood fibers were characterized using scanning electron microscopy (SEM) coupled with energy-dispersed X-ray analyzer (EDXA), Fourier Transform Infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The study found that after modification, the moisture adsorption rate of wood fibers had decreased and the surface hydrophobicity of the fibers had been promoted. The fibers modified with MTMS adsorbed the least amount of moisture. The study also found that while hydrolyzed silane penetrated into wood fibers and reacted with their chemical components, long chains of the silane hindered the degree of that penetration.

Changing wood color with physical treatment is an alternative method to avoid the use of chemicals harmful to the environment. However, despite this advantage, there are few studies on the chemistry and colorimetry of pre-hydrolyzed wood. The objective this research was to evaluate the content of extractives, lignin and holocellulose, lightness (L), red matrix (a*), yellow matrix (b*), saturation (C), and tonality angle (H) on strand board particles of pre-hydrolyzed pine and eucalyptus. Strand board particles measuring 23 x 90 x 0.30 mm in width, length, and thickness, respectively, were pre-hydrolyzed at 130, 150, and 170 °C during 7 or 21 minutes. The temperature had a significant effect on the chemical composition of wood. The pre-hydrolysis temperature of 170 °C resulted in higher chemical modifications. The pre-hydrolysis reduced the equilibrium moisture content of pine and eucalyptus particles, especially at 170 °C. Color modification due to pre-hydrolysis varied according to treatment conditions. Pine particles were more resistant color changing than the eucalyptus particles.

Solvent extracts of Rhus verniciflua Stokes wood were made using decompressing inner ebullition, and a Box-Behnken design was used to optimize extraction conditions to produce an extract that inhibited tyrosinase activity. The chemical compositions and inhibition rates were determined in extracts made with petroleum ether, ethyl acetate, n-butanol, and an aqueous fractionation. The ethyl acetate fraction had the highest total phenolic content and inhibition rates. The main flavonoids in this fraction were 0.531% fisetin, 7.582% fustin, 0.848% sulfuretin, and 0.272% butein. The effects of the extract on the monophenolase and diphenolase activity of mushroom tyrosinase were studied using the Lineweaver-Burk equation to determine the effect of the extract on inhibition of tyrosinase activity. The results showed that the extract inhibited both the monophenolase and diphenolase activity of the enzyme. The IC50 of the ethyl acetate extract was 308 μg/mL, with the lag period of the enzyme being obviously lengthened; it was estimated to be 2.45 min in the absence of the inhibitor and extended to 9.63 min in the presence of 500 μg/mL of extract. The ethyl acetate extract acted as a mixed type inhibitor. The KI was less than the KIS, which demonstrates that the [ESI] is less stable than [EI], suggesting that the extract could easily combine with free enzyme in the enzyme catalysis system, thus affecting enzyme catalysis on the substrate.

To provide an in-depth understanding of preventing occupational diseases and improving working conditions, characteristics of inhalable dust were studied. The results showed that total dust concentration (TDC) from mechanical sanding, portable planning and sanding, putty sanding, and painting sanding with inadequate exhaust ventilation were higher than occupational exposure limits (OELs). The more the furniture material was sanded and the worse the dust exhaust apparatus, the higher the TDC was. The TDC from portable planer sanding and dry sanding and putty sanding was in the range from 8.4 mg/m3 to 8.7 mg/m3 and from 5.3 mg/m3 to 8.4 mg/m3, respectively. The TDC from mechanical sanding and painting sanding was in the range from 4.4 to 6.4 mg/m3 and from 3.4 mg/m3 to 4.9 mg/m3, respectively. More than 90% suspended particulate matter in their TDC had a PM10 in all aforementioned results. The sanding procedure produced 6.7% to 8.2% free silica in the total particulate matter, in addition to wood dust, putty dust, or painting dust. Heavy metals in dust from putty sanding and painting exceeding the OELs were lead (Pb; > 0.3 mg/m3) and cadmium (Cd; > 0.01 mg/m3). There was a large amount of granular grinding material, cluster putty, planar painting dust, and a small amount fibroid wood dust in the dust from putty sanding and painting sanding.

Corncob, an underutilized agricultural byproduct, was used as the raw material to make a dry-strength additive for paper. Corncob was ground into 80, 100, 150, and 200 mesh powder. The powder was treated with sodium chlorite to remove lignin, and the resulting holocellulose was modified with hydrogen peroxide. The influences of oxidation time, concentration of hydrogen peroxide, dosage of paper strength agent, and the dosage of aluminum sulfate on the paper properties were studied. The results indicate that the oxidized corncobs holocellulose can improve the tensile index, burst index, and folding endurance of paper. Compared with control paper, when the concentration of hydrogen peroxide was 0.9%, the tensile index, burst index, and folding endurance were increased by 24.2%, 14.1%, and 463.8%, respectively. The particle size of raw material, dosage of strengthening agent or aluminum sulfate greatly influences paper properties. Scanning electron microscopy (SEM) analysis showed that the combination between the fibers was improved after adding the strengthening agent, thus improving the strength of the paper. The results can provide a new method for value-added use of corncob.

Waste clay recovered from palm oil mill effluent (POME) was characterized and used as an enzyme-supporting material for the cassava saccharification process. The clay was treated by the Soxhlet extraction method to remove the residual oil and then characterized using a BET surface area analyser, XRF, XRD, FTIR, TGA, and FESEM. The chemical analysis showed that the sample had a high amount of CaO (93%) with a minor content of SiO2 (1.378%) and Al2O3 (0.707%), with a surface area of 1.15 m2/g. The XRD analysis revealed the major mineral presence to be calcite, as confirmed by FESEM analysis. The FTIR results also attested to the presence of a calcite phase and carbonate groups. To study the performance of the waste clay for enzyme immobilization application, the recovered waste clay was further used as an enzyme supporting material for enzyme immobilization in the cassava saccharification process. Results showed that the enzymes were successfully encapsulated and gave the highest immobilization yield of 70% with 2% clay concentration. In addition, the encapsulated enzymes also enhanced the reusability, where the enzyme retained 32% of its activity after seven cycles of saccharification processing.