Volume 7 Issue 4

The objective of this study was to determine the processing conditions for obtaining improved pulp properties from the kraft pulping process with an alkali pre-extraction stage. Before the kraft pulping, a pre-extraction of hemicelluloses from mixed hardwood chips was performed with two different alkali concentrations (3% and 12% as Na2O) at 150 °C for 90 minutes. The kraft pulping of the pre-extracted chips was then conducted in two ways: with either the H-factor alone controlled or with both the H-factor and the alkali charge controlled. When the chips were pre-extracted with the 3% alkali charge and with the kraft pulping controlled to an H-factor of 500, the yield and properties of the pulp were higher than those of the reference kraft pulp. The 12% alkali pre-extraction and kraft pulping resulted in a low yield of screened pulp. However, when the alkali charge and the H-factor were adjusted together, the pulp yield remained constant and the pulp properties improved in comparison to the reference pulp for both the 3 and 12% cases.

The extraction parameters of intracellular polysaccharide (IPS) from Hypsizigus marmoreus SK-01 mycelia were optimized, and the antioxidant activities of IPS were investigated. The optimum conditions of IPS extraction were predicted to be: an ultrasonic treatment time of 618.07 s, an extraction temperature of 84.53 °C, a pH of 7.57, and an IPS yield of ca. 6.84%. The in vitro inhibition effects of IPS on hydroxyl, superoxide anion, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals were 52.63 ± 3.19%, 68.21 ± 5.09%, and 63.43 ± 5.27%, respectively, and the EC50 values of IPS were 0.85 ± 0.05 g/L, 0.47 ± 0.03 g/L, and 0.62 ± 0.04 g/L, respectively. The activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) in mice blood were 2.52 ± 0.02 U/mL, 453.19 ± 38.43 U/mL, and 118.59 ± 9.64 U/mL, respectively. The results provide a reference for large-scale extraction of IPS by H. marmoreus SK-01 in industrial fermentation, suggesting that IPS can be used as a potential antioxidant that enhances adaptive immune responses.

Causticizing precipitated calcium carbonate (CPCC) as a by-product of the green liquor causticizing process can be used as paper filler to save resources and reduce costs. In this study, CPCC was prepared with green liquor and quicklime, which were obtained from an alkali recovery line of a paper mill. The factors influencing crystal morphology of CPCC, such as slaking temperature, slaking time, and causticizing time were investigated. The morphology of CPCC was observed and analyzed for optimizing reaction conditions. The following were compared: properties of CPCC obtained in this study, conventional CPCC (white mud) from a paper mill, and commercial PCC as fillers. The results showed that slaking time and causticizing time were important for morphology control. Spindle-like and rod-like CPCC obtained in this study had better drainability and retention, higher paper bulk, opacity, and physical strength compared to conventional CPCC, and had nearly the same performances as commercial PCC.

Panels were made from Arundo donax L. particles bonded with different non-modified starches as adhesive without chemical additives by hot-pressing at a low temperature (110 ºC) and pressure (2.6 N/mm2). The experimental panels were tested for their physical and mechanical properties according to the procedures defined by the European Union (EN) Standard. The microstructure of samples was observed by scanning electron microscopy (SEM). Panels manufactured with potato starch had the highest modulus of rupture and modulus of elasticity, meeting the standard for load bearing (grade P4 for indoor use in dry ambient) (EN 312: 2003). Panels made with corn starch and wheat flour, at a 10% level and three pressing cycles met the standard for general uses (grade P1). Panel bonded with rye bran flour achieved the best internal bond strentgh. The water resistance was poor and needs to be improved.

Typha capensis (TC), a highly prolific, invasive grass found in many parts of the world, is a common pest that grows in waterways, but it may be a good lignocellulosic substrate for bioethanol production. Sulfuric acid-catalyzed ethanol organosolv pretreatment was used to investigate the possibility of harnessing the benefits of both fermentable sugars and lignin by reacting at varying defined severity levels. It was observed that TC polysaccharides were particularly susceptible to hydrolysis, which was associated with the formation of a large amount of pseudo-lignin due to the degradation of sugars. Pseudo-lignin had a negative impact on enzymatic hydrolysis. At optimal conditions, the process enabled the fractionation of TC into glucan-rich solid fractions with enhanced digestibility, recovery of organosolv lignin, and easily hydrolysable hemicellulose sugars in the liquid stream of pretreatment analytes. About 68.33% of the glucan in the raw TC was recovered, and 85.23% fermentable sugars from water-soluble and enzyme-hydrolyzed pulp were attained. Up to 67% of the initial lignin in TC was extracted as ethanol organosolv lignin (EOL).

Cellular behaviors and a xylanolytic-cellulolytic enzyme system of Tepidimicrobium xylanilyticum BT14 towards xylan-rich plant biomass degradation were characterized. During the exponential growth phase, the bacterial cells were bound tightly to the growth substrate where the degradation zones appeared mostly around the cells, indicating that the xylanolytic-cellulolytic enzyme system was linked to the cell surfaces. Interestingly, several cells appeared to secrete extracellular matrix to connect to their neighbors, and the matrix disappeared when cells passed to the stationary growth phase. Cationized-ferritin staining resulted in a dense assembly of bulbs, protuberance-like structures on the growing bacterial cell surfaces. The cell-associated proteins derived by sonication contained predominated xylanase with relatively low carboxymethyl-cellulase (CMCase) activities, suggesting that the xylanolytic-cellulolytic enzyme system occurred as a cell-associated enzyme. By means of gel-filtration chromatography, a high molecular mass protein with the estimated size of 2000 kDa was retrieved from the cell-associated enzymes, and it appeared as a single protein band on non-denaturing gel. However, more bands were obtained after the protein was boiled with sodium dodecyl sulfate and β-mercaptoethanol – which contained 4 xylanases and one CMCase – suggesting that these proteins were organized as a multienzyme complex (MEC) in natural form. Additionally, the predominated xylanolytic MEC preferred binding to cellulose rather than xylan.

A heterogeneous process for the hydrolysis of bamboo into reducing sugars, a process catalyzed by biomass char sulfonic acids (BC-SO3Hs), was carried out under microwave irradiation. This transformation technology was nearly ineffective with regards to the hydrolysis of fresh bamboo because of the impeding lignin that was wrapped around the cellulose, but the hydrolysis proceeded efficiently when the hemicellulose, and especially the lignin in bamboo, were partly removed through pretreatment with an aqueous ZnCl2 solution under microwave irradiation. The BC-SO3H catalyst bearing –SO3H, OH, and COOH groups showed much higher turnover numbers (TON, 0.64 to 1.07) for the hydrolysis of the pretreated bamboo than did the dilute H2SO4 solution (TON, 0.08). This is likely due to its strong affinity for b-1,4-glycosidic bonds of cellulose. The microwave irradiation resulted in much higher hydrolytic efficiency than did conventional heating. This likely resulted from the microwave irradiation’s unique role in activating the cellulose molecules and heightening particle collisions, effects that can remarkably accelerate this process of heterogeneous catalysis.

This paper demonstrates the preparation of transparent biocomposites from chitin nanofiber using a series of simple mechanical treatments after the removal of proteins and minerals. Field emission scanning electron microscopy (FE-SEM) images show that the prepared chitin nanofibers are highly uniform with a width of less than 50 nm and a high aspect ratio. Due to the nano-size, the fibers are small enough to retain the transparency of the neat polymethylmethacrylate resin. Light transmission of the obtained chitin/PMMA biocomposite was 90.2%, in comparison to the neat resin, which was 92.6%. Mechanical property tests showed that chitin nanofibers significantly improved the tensile strengths and Young’s modulus of the neat PMMA, which increased from 43.8 MPa to 102 MPa and 1.6 GPa to 3.43 GPa, respectively. PMMA resin was found to be well dispersed in the biocomposite and had little effect on the tensile properties of the material. The properties mentioned above qualify the chitin nanofiber as a green and high-performance candidate having potential to be applied in next-generation optical electronic and building systems as a commercially available material.

Ethyl levulinate (EL) can be produced from bio-based levulinic acid (LA) and ethanol. Experimental investigations were conducted to evaluate and compare the performances and exhaust emission levels of ethyl levulinate as an additive to conventional diesel fuel, with EL percentages of 5%, 10%, 15% (with 2% n-butanol), and 20% (with 5% n-butanol), in a horizontal single-cylinder four stroke diesel engine. Brake-specific fuel consumptions of the EL-diesel blends were about 10% higher than for pure diesel because of the lower heating value of EL. NOx and CO2 emissions increased with engine power with greater fuel injections, but varied with changing EL content of the blends. CO emissions were similar for all of the fuel formulations. Smoke emissions decreased with increasing EL content.

High-pressure steam treatment (HPST) is a potential alternative method for the modification of lignocellulosic materials. The effect of HPST on oil palm mesocarp fibers (OPMF) was successfully investigated with treatment conditions of 170 ºC/ 0.82 MPa, 190 ºC/ 1.32 MPa, 210 ºC/ 2.03 MPa, and 230 ºC/ 3.00 MPa for 2 min. treatment time. Significant changes in the colour, smell, and mechanical properties of the samples were observed after the treatment. Scanning electron microscope (SEM) images revealed changes in the surface morphology of the OPMF after the pretreatment. The degradation of hemicelluloses and changes in the functional groups of the lignocellulosic components were identified using Fourier Transform Infrared (FTIR) and Thermogravimetric (TG) analysis. These results suggest that HPST is a promising method for the pretreatment of OPMF.