Volume 18 Issue 2

Effects of high temperature pretreatment and inoculation of Bacillus coagulans were determined relative to the physicochemical properties and bacterial community of aerobic composting of chicken manure. Chicken manure was pretreated with high temperature for 0 h (CJ), 0.5 h (T-0.5h), 1.0 h (T-1.0h), 1.5 h (T-1.5h), and 2.0 h (T-2.0h) and then inoculated with B. coagulans. Chicken manure without high temperature pretreatment was included as control (CK). The results showed that the temperature of manure in CJ, T-0.5h, T-1.0h, T-1.5h, and T-2.0h groups was 2.2 to 8.4 °C higher than the chicken manure in CK within 1 day. On day 3, the chicken manure temperature reached a peak, which was 1.5 to 7.7 °C higher than that in the CK (56.8 °C). Both inoculation of B. coagulans and high temperature pretreatment increased the abundance and diversity of the bacterial community. The abundance of Firmicutes in T-1.5h was significantly higher than that in CJ. In the temperature decreasing period, the abundance of Bacillus in T-1.5h group was significantly higher than that in the CK and CJ. Overall, it was concluded that high temperature pretreatment and B. coagulans inoculation can accelerate the temperature elevation, increase the temperature of compost, and regulate the structure of bacterial community.

Seed health testing, using the blotter method, revealed some fungal growth on the seed surface of one accession of Indian trumpet flower/Broken bones tree (Oroxylum indicum (L.) Kurz) collected from Kokrajhar, Assam, India. The fungus was identified as Diaporthe phaseolorum (Cooke & Ellis) Sacc. based on morphological characters. Later, the identity was re-confirmed by DNA sequencing using ITS gene sequencing (NCBI Sequence Id: MT154253.1) and a large subunit of rRNA (NCBI Sequence Id: OL798081.1). Literature reveals that D. phaseolorum is a destructive pathogen causing severe yield losses in various host crops. However, detection of D. phaseolorum in Indian trumpet flower seed followed by pathogenicity on its seedlings confirms that O. indicum is a new host record. Being a destructive pathogen of several other crops, such as seed decay and stem canker in soybean, it may pose a serious threat to future cultivation of this herbal plant.

Leaf and stem fibers of Sorghum halepense L. (SH) were investigated as fillers for recycled polypropylene (RPP) at 10, 20, and 30 wt%. The effects of SH in RPP on the thermal and mechanical properties of composites were investigated by tensile and bending tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). It was found that mechanical properties of the RPP composites decreased but their elasticity modulus increased. The addition of SH fibers to the polymer matrix changed the thermal properties of RPP. A slight decrease in DSC crystallinity was observed with the addition of 10% SH leaf and stem fiber to the polymer matrix and then the percentages of crystallinity increased with the addition of 20% and 30% SH leaf and stem fiber. The SEM images showed that the SH fibers mixed well with the polymer matrix without agglomeration, and the fracture sections of the composites were less rough than that of the RPP by itself.

To eliminate toxic formaldehyde from wood-based panels, a new formaldehyde-free wood adhesive (named OL/PEI adhesive) was synthesized by a reaction of oxidized lignin (OL) and polyethylenimine (PEI) reaction in the presence of sodium periodate. The curing mechanism of the OL/PEI adhesive was clarified by Fourier transform infrared spectroscopy (FTIR) and solid-state cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS¹³C-NMR) spectroscopy. The results showed that the sodium periodate could selectively oxidize wheat straw lignin to produce the ortho-quinone, and then the ortho-quinone in OL could further react with amino groups in PEI to form the OL/PEI adhesive. The as-prepared poplar particleboard was investigated with regard to hot-pressing temperature, the hot-pressing time, the OL/PEI weight ratio, and the dosage of OL/PEI adhesive. Under the optimum conditions, e.g., hot pressing temperature of 180 °C, hot pressing time of 13 min, the OL/PEI weight ratio of 1:1, and the dosage of 10%, OL/PEI adhesive was found to disperse evenly into the voids among the shavings of poplar particleboard, followed by the curing of OL/PEI adhesive using hot-pressing to form tightly bonds between the shavings. The resulting particleboard reached the requirement of mechanical properties (GB/T 4897.3-2003), higher water resistance properties, and better heating resistivity. This study demonstrated a new way to produce a formaldehyde-free wood adhesive with unique properties. This material could replace formaldehyde wood adhesive in wood bonding.

The pyrolysis of medlar seeds was performed at 350, 450, 550, and 650 °C with and without K₂CO₃, MgO, and expanded perlite (10 wt%). The maximum dichloromethane extract yield (6.70 wt%) was obtained at 450 °C in the pyrolysis experiments without catalyst, while the maximum bio-oil yield (50.3 wt%) was obtained at 650 °C in the presence of perlite. The dichloromethane extract and bio-oil yields decreased noticeably with the use of MgO and K₂CO₃. The bio-oils obtained from the non-catalytic runs mainly consisted of phenolic compounds. The use of catalysts had a noticeable effect on the composition and higher heating values of the bio-oils. The use of K₂CO₃ increased the relative content of 2-methoxyphenol at all tested temperatures and the relative content of 2,6-dimethoxyphenol and 2,6-dimethoxy-4-methylphenol increased with the use of expanded perlite at above 550 °C, while the use of MgO led to an increase in the relative content of 2,6-dimethoxy-4-methylphenol at above 550 °C. The bio-oil with the maximum higher heating value (30.4 MJ/kg) was obtained at 450 °C with the use of perlite. This study showed that medlar seeds are a good alternative source of waste biomass in the production of bio-oil that can be used as a biofuel.

Statistical design and mathematical modeling were used to investigate the fed-batch enzymatic hydrolysis of steam-exploded sugarcane bagasse (195 °C, 7.5 min). First, a Box-Behnken experimental design was used to evaluate the effect of enzyme loading (8, 24, and 40 FPU g^-1 glucans of Cellic CTec3^®), stirring speed (100, 150, and 200 rpm), and substrate total solids (5, 12.5, and 20 wt%) on the release of glucose equivalents (GlcEq, mostly glucose) after hydrolysis for 48 h in batch mode. A simplified kinetic model was used to fit the experimental data, in which specific activities in Cellic CTec3 were not differentiated, enzyme adsorption was ignored, and end-product inhibition was only attributed to glucose accumulation. The adjusted kinetic model was used to predict the effects of substrate and enzyme intermittent feedings in fed-batch hydrolysis experiments. Compared with batch experiments at 20 wt%, the proposed fed-batch procedure was able to increase GlcEq productivity by nearly 68% using the same enzyme loading, producing substrate hydrolysates containing 91.8 g L^-1 GlcEq.

Bacterial nanocellulose (BNC) can be produced using a variety of substrates as fermentation medium for use in various biomaterial applications. This study aimed to optimize the production of and characterize the BNC derived from lemongrass leaves (L-BNC) obtained by symbiotic culture of bacteria and yeast (SCOBY) kombucha. The lemongrass leaves (10, 15, and 20 g/L) and sugar (30, 50, and 70 g/L) were incubated for 14 d at 30 °C. The optimal treatment was used to ferment kombucha for 21 days at 30 °C, with initial SCOBY inoculum of 3% w/v and kombucha of 10% v/v for the resulting L-BNC. The L-BNC was characterized using scanning electron microscopy-energy dispersive X-ray (SEM-EDX) spectroscopy, Fourier-transform Infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD). The optimal parameters of the lemongrass kombucha fermentation production process were lemongrass content 10 g/L and sugar content 30 g/L with the incubation period of two weeks for 56.8 g/L of SCOBY production. The SEM analysis of L-BNC revealed a three-dimensional fibrous extremely fine network of randomly arranged nanofibrils with diameter of 163 ± 34 nm and hydrogen bonds present in L-BNC fibril units. Meanwhile, XRD results showed a crystallinity of 67.2%.

The demand for high-grammage paper, 150 g/m² or more, is increasing for product protection and aesthetic value. Fold cracking, resulting from high mechanical pressure during folding, considerably decreases the economic feasibility of such products for papermaking companies. Fold cracking can be reduced through creasing, but defects possibly occur as fiber bonds are broken. In this study, the fold cracking of high-grammage paper that was not treated through creasing was explored. The mechanical and folding properties of six types of pulp fibers were evaluated based on their beating degree. The fines content of the fiber differed according to the beating condition. Using pulp with low fines content improved the folding properties. The mechanical properties of hardwood pulp were enhanced with increased beating degree. The mechanical properties of softwood pulp were considerably increased, and fold cracking occurred with increasing beating degree. Therefore, to improve the fold cracking, beating should be applied appropriately, following the type and mixing ratio of pulp fibers. Finally, softwood pulp mixing is proposed as a strategy to control fold cracking while maintaining the unique characteristics of high-grammage paper.

The primary purpose of this study was to delineate the most significant factors in the wood impregnation process. For this, the authors prepared larch (Larix kaempferi) and Korean pine (Pinus koraiensis) wood and used alkaline copper quaternary as an impregnation solution. The chamber temperature was adjusted to 25, 50, and 80 °C, and the pressure was adjusted to 100, 200, and 300 psi. The impregnation process was maintained for up to 90 min. Multiple regression analysis was used to investigate the effects of temperature, time, and pressure in terms of amount of solution impregnated during the process. Factors affecting the amount of solution impregnated were as follows: the effect of pressure was greater than that of time, which was greater than that of temperature. Therefore, pressure was the most critical factor in the wood impregnation process.

Fold cracking, which reduces the economic feasibility of paper-making, is a localized surface deformation caused by extreme bending stress. Most paper products, such as base paper and coated paper, generate fold cracking during folding processing. To control fold cracking, the mechanical properties of the base paper can be strengthened, and the flexibility of the structure can be increased by controlling the modification in pulp fibers and stock preparation conditions. This study analyzed the changes in the mechanical properties of high-grammage paper in response to the addition of precipitated calcium carbonate (PCC) and cationic starch (C-starch). The application of inorganic filler (PCC) drastically reduced the internal bond strength and tensile strength, causing fold cracking, whereas C-starch increased the bond strength between fibers, which improved the tensile strength, internal bond strength, and elongation. However, when applied independently, fold cracking occurred because of extreme increase or decrease in strength. Therefore, the combined application of C-starch and PCC made it possible to form a paper-based structure with high fold cracking resistance. Moreover, when the fold cracking resistance was excellent, the mechanical properties were balanced without being biased in one direction even under conditions of relatively low mechanical properties.