Research Articles

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.

The anatomical characteristics of the culms and culm bases of ssanggol- and min-bamboo, which are mutated species of Phyllostachys bambusoides, were investigated using optical microscopy to understand the material properties. The vascular bundles in the culms and culm bases of both species were type I. There were a few abnormal vascular bundles in the culm base of ssanggol-bamboo, and more developed fiber bundles in the inner part of min-bamboo. A wavy surface was observed in the pith cavity of the ssanggol-bamboo culms. In the inner part, the vascular bundles of min-bamboo culms showed a regular diagonal arrangement, whereas those of ssanggol-bamboo were distributed randomly. In the culm base, ssanggol-bamboo had a significantly higher proportion of parenchyma and vessels, whereas min-bamboo had a higher fiber proportion. Both species had comparable proportions of cells in their culms. The vascular bundle density of min-bamboo was significantly higher than that of ssanggol-bamboo, whereas ssanggol-bamboo showed a significantly larger vessel diameter than min-bamboo. Ssanggol-bamboo had a shorter parenchyma cell length and larger parenchyma cell width than min-bamboo, whereas the min-bamboo culm showed a longer fiber length than that of ssanggol-bamboo. Furthermore, in the culm base, the fibers of ssanggol-bamboo were longer.

The voluminous generation of distilled spirits lees (DSL) in China presents a challenge for proper disposal and potential environmental pollution. In an effort to address this issue, this study aimed to find a resourceful solution for DSL utilization. The application of incinerated rice husk ash as a mortar supplementary material in cement provides an innovative solution for the disposal of DSL. Five samples of distilled spirits lees ash (DSLA) were produced using both muffle furnace (MF) and fluidized bed (FB) combustion at different temperatures. The properties of DSLA were characterized through measurements of specific surface area and observations using scanning electron microscopy (SEM). Mortar specimens were prepared by replacing 10% of cement with DSLA, and strength tests were conducted. The SEM results revealed the crisscross mesh structures in the DSLA samples. Additionally, the findings indicated a strong connection between the specific surface areas and the micromorphology. In this work, all DSLA samples, except for the one produced in FB at 800 °C, could improve compressive and flexural strengths in the prepared mortar specimens and were suitable for employment as cement additives.

The influence of hydrothermal treatment (HTT) on the hemicellulose, i.e. glucomannan/galactoglucomannan (GM/GGM) and arabinoglucurono-xylan (AGX) in Japanese cedar was examined using mild temperatures (95 °C and 120 °C) for its kiln drying. Based on infrared spectra, only a slight change due to HTT was observed in the hemicellulose chemical structure. The quantitative changes of the major chemical components including lignin, cellulose, and hemicellulose also exhibited slight differences among samples. However, the molecular chain-length composition of GM/GGM and AGX in the cell walls decreased clearly with HTT, as well as with an increase in temperature. Also, it was found that the strength of the interaction between cellulose and hemicellulose molecules such as GM/GGM and AGX in cell walls decreased depending on the increase in HTT temperature. These results showed that the polymeric structure of GM/GGM and AGX was degraded by hydrolysis at 95 °C of HTT and proceeded further at 120 °C of HTT.

Urea-formaldehyde is one of the commonly used resin types in the particleboard industry. In this study, the effect of nanofibrillated cellulose (NFC) and titanium dioxide (TiO₂) addition in the formulation of the urea formaldehyde resin on the physical, mechanical, and morphological properties of particleboard samples was investigated. The NFC (0.5% and 1%) and TiO₂ (0.5%, 1%, and 2%) were added to the 10% adhesive formulation. Two different pressure times, 4 and 8 min, were applied during the production of samples. Subsequently, the water absorption (WA), thickness swelling (TS), internal bonding strength (IB), modulus of rupture (MOR), modulus of elasticity (MOE), scanning electron microscopy (SEM), and statistical analysis of test samples were determined. The thickness swelling values ranged from 19.9% to 34.9% and WA values were from 74.50% to 110.6%. However, the maximum MOR, MOE, and IB values were 22.2 MPa, 2570 MPa, and 1.1 MPa, respectively.