Volume 15 Issue 2

Lignocellulose is considered to be a good resource for producing renewable energy. This paper reports on the effect of three surfactants [polyoxyethylene (80) sorbitan monooleate (POE80), rhamnolipid, and tea saponin] on cellulase (CBH/EG/BG) expression of Saccharomyces cerevisiae in simultaneous saccharification and fermentation (SSF) of corncob. In this work, the optimal surfactant concentrations for yeast growth were 0.1% POE80, 0.05% rhamnolipid, and 0.002% tea saponin. In the process of SSF, the reducing sugar content with 0.1% POE80 was 13.5% higher than the control at 24 h. The reducing sugar content with 0.05% rhamnolipid was higher than the control at 120 h, and reached the maximum difference of 18.2% in 120 h. The addition of 0.002% tea saponin exhibited the lowest promotion effect on the reducing sugar content in SSF compared with POE80 and rhamnolipid. However it reached the maximum difference of 8% in 120 h. Compared with the control, 0.1% POE80, 0.05% rhamnolipid, and 0.002% tea saponin presented different degrees of increase in reducing sugar content and viable count in the SSF. The results showed that the addition of the surfactants in SSF increased the growth rate of strains and promoted the saccharification efficiency of the substrate. This study lays a foundation for the application of surfactants in bio-energy research.

A high-performance hydrogel was successfully fabricated using xylan-rich concentrated steam explosion liquid (CSEL). The method used was a free-radical graft copolymerization of acrylic acid (AA) and acrylamide (AM) onto a primarily xylan backbone in CSEL, with a redox system of ammonium persulfate/anhydrous sodium sulfite as the indicator and N,N`-methylenebisacrylamide (MBA) as the cross-linker. The effects of independent parameters (the dosages of the indicator, AM, AA, and the cross-linker) on the swelling ratio of the as-prepared hydrogel were studied via an optimal design of the response surface methodology (RSM). Under the optimal conditions (80.9 mg of initiator, 349.6 mg of AM, 988.7 mg of AA, and 9.39 mg of cross-linker), the swelling ratio of the prepared hydrogel (Xyl-AM-co-AA) was 276.6 g/g, which was close to the predicted value (255.7 g). The swelling behaviors of Xyl-AM-co-AA at different temperatures and pH values were also analyzed. The results showed that the swelling ratios varied at different temperatures and pH values, implying their potential use as smart materials. Analysis by Fourier transform infrared spectroscopy and scanning electron microscopy confirmed the cross-linked and hygroscopic behavior of Xyl-AM-co-AA.

In order to improve the processing quality of wood parts, an orthogonal experimental design of five factors and four levels was adopted, and a water-jet assisted laser cutting experiment on Korean pine (Pinus koraiensis) was conducted. Moreover, by using range analysis, the influences of the defocusing amount, cutting speed, laser power, water pressure, and water jet angle on the processing quality of Korean pine parts were evaluated, and the optimum process parameters were determined. The test results show that when the defocusing amount was -1 mm, water jet angle was 30°, laser power was 48 W, water pressure was 1.0 MPa, and cutting speed was 25 mm/s, the best processing quality of Korean pine parts was obtained.

Changes in maple wood’s pH and color (Acer pseudoplatanus) were evaluated before and after thermal treatment process with saturated water steam. Maple wood was thermally treated at temperatures: tI = 105 ± 2.5 °C, tII = 125 ± 2.5 °C, and tIII = 135 ± 2.5 °C for τ ≤ 12 hours. Direct pH measurement of maple wood with a moisture content above the fiber saturation point (FSP) was performed using a pH-meter SI 600 with a Lance FET + H puncture probe. The polynomial dependence of pH and total color difference ∆E* on temperature t time τ was calculated by statistical processing of measured results. The correlation between the total color difference ∆E* of maple wood in the process of thermal color modification and the pH value is expressed y the equation: ∆E* = 4.5516∙(pH)2 – 48.405∙(pH) + 134.35. This dependence is a suitable tool for assessing the achieved color change based on the change of wood pH in the technological process.

Phosphate-solubilizing microorganisms have been considered as a novel alternative approach to provide phosphate fertilizers that promote plant growth. In this study, three strains were isolated and identified as Penicillium oxalicum FJG21, Penicillium oxalicum FJQ5, and Bacillus subtilis BPM12, with a relatively high phosphate-solubilizing activity. Various phosphate sources were investigated, and Ca3(PO4)2 was identified as the effective phosphate source. Factors governing the phosphate-solubilizing activity of the strains included carbon and nitrogen sources, initial pH, and fermentation time. A high soluble phosphorus content was achieved with 529.0 μg·mL-1, 514.0 μg·mL-1, and 330.7 μg·mL-1 for Penicillium oxalicum FJG21, Penicillium oxalicum FJQ5, and Bacillus subtilis BPM12, respectively. An inverse correlation of the quantity of soluble phosphorus content and the pH value of the medium was observed. In addition, Bacillus subtilis BPM12 displayed a prominent capability of producing indole acetic acid. Penicillium oxalicum FJG21 and Penicillium oxalicum FJQ5 exhibited high cellulase activities. These phosphate-solubilizing microorganisms with good phosphate-solubilizing capability and growth-promoting ability are the promising strains for agricultural utilization.

Elementary fibres isolated from mechanically processed technical hemp were axially sectioned and imaged with transmission electron microscopy (TEM) to reveal details of the axial morphology of dislocations in the fibre. The overall aim was to investigate the detailed axial structural changes that the fibres undergo during processing, to help better understand the alterations in the deformation behaviour the fibres undergo following processing. The images showed the structure and morphology of dislocations as well as the different forms of damage that processing produced in the fibre structure, such as misalignment of the microfibrils, delamination, and buckled cellulose microfibrils. Furthermore, the results of this work show the ability that axial sectioning of the fibre has to reveal new details of the cell wall structure of hemp to offer new insights in the study of the fibre structure. In turn, the results of this work may help explain the mechanical behaviour of the fibres when they are loaded, as well as help explain the greater chemical accessibility of dislocations, for example, when the fibre is acid hydrolysed.

Utilizing four kinds of straw fibers (sorghum, rice, corn, and soybean) as filling fibers, polylactic acid (PLA) and poly (adipic acid)/polybutylene terephthalate (PBAT) in a mixture (7:3) were used as matrix to prepare composite materials by a hot pressing molding process. The mechanical properties, and thermal stability of the four fiber-filled composites were evaluated. The composites had high interfacial quality and no obvious voids. The soybean straw/PLA/PBAT composite had the best interfacial quality. PLA/PBAT-based composite materials were examined. The experimental results show that the soybean straw/PLA/PBAT composite had the best tensile strength, bending strength, and impact strength (14.3 MPa, 19.5 MPa and 3.23 KJ·m-2, respectively), which was 25.3%, 14.6%, and 27.8% higher than that of the corn straw/PLA/PBAT composite. The thermal stability of the corn straw/PLA/PBAT composite was the best, with an initial decomposition temperature of 286 °C, and the residual amount was 7.3%.

The concentrates of coking effluents are toxic and technically challenging to treat. Environmental protection demands an efficient and cost-effective technique for coking wastewater treatment. The intertidal marine macro alga Ulva prolifera has a high tolerance to various environmental stresses. In this study, U. prolifera was collected from an intertidal field and tested in a laboratory-scale photobioreactor for potential bioremediation of coking effluent concentrate. Algal physiology and water quality were measured. During treatment, the quantum yield Fv/Fm and effective quantum yield Y(II) values showed 12% and 15% decreases in 24 h, respectively, and a complete recovery in 168 h. The algal physiological characteristics indicated that light irradiance provided in a sine pattern of enhanced algal growth by 53% in the coking concentrate. The removal efficiency for total nitrogen and total phosphorus was up to 26.1% and 68.5% in 24 h, respectively. It also showed high removal efficiencies for some heavy metals, chemical oxygen demand, biological oxygen demand, and nutrients within 24 h. The feasibility of using U. prolifera for coking concentrate treatment was also considered. This study provided a possible bioremediation technique for wastewater treatment, especially for concentrates of coking effluent, in the coking industry.

Rose dregs were used for laccase production by the strain Pycnoporus sp. W-9 under liquid fermentation, and the obtained laccase was used for phenol degradation. The conditions for laccase production were optimized by Box-Behnken design, and the phenol degradation conditions using the crude laccase were optimized by central composite design. The optimal conditions for laccase production by the strain W-9 were as follows: rose dregs (40 g/L), KCl (0.144 g/L), KH2PO4 (1 g/L), K2HPO4 (0.699 g/L), NaCl (0.2 g/L), MgSO4·7H2O (0.3 g/L), CuSO4·5H2O (0.306 g/L), Tween 80 (0.2 g/L), and CaCO3 (1 g/L), at a pH of 6.0, incubated at 30 °C and 200 rpm for 7 d. The corresponding laccase yield reached 17.4 U/mL, which was approximately 1.8 times the original production. The optimal conditions for phenol removal by the crude laccase were as follows: laccase (12.2 U/mL), 0.1 mol/L citric acid-disodium hydrogen phosphate buffer (pH 3.5), phenol (100 μg/mL), and Triton X-100 (284 μg/mL), incubated at 45 °C for 2 h. The corresponding phenol degradation rate reached 86.6%. These results should be useful for utilization of rose dregs and bioremediation of soil and wastewater.

In order to optimize the sulfonated chemi-mechanical pulping of palm oil empty fruit bunch, the response surface methodology was employed. It was intended to determine the optimum level of sodium sulfite dosage, sodium hydroxide dosage, maximum cooking temperature, and cooking time at the sulfonation stage, and their influences on paper sheets properties were analyzed. An optimum compromise was obtained, and the sodium sulfite dosage, sodium hydroxide dosage, maximum temperature, and cooking time were 18%, 4%, 155 °C, and 100 min, respectively. The density, bursting strength index, tensile strength index, and tearing strength index were 0.5622 g/cm3, 2.60 kPa·m2/g, 45.01 N·m/g, and 7.53 mN·m2/g, respectively.