Volume 20 Issue 3

Hydrothermal carbonization (HTC) of corn straw causes hydrolysis and pyrolytic reorganization of the carbon skeleton, leading to the formation of polycyclic aromatic hydrocarbons (PAHs). When used as a soil amendment, hydrothermal carbon can lead to soil contamination, increased biotoxicity, and potential harm to ecosystem health. To systematically evaluate PAHs formation mechanisms, single-factor experiments were carried out by treating corn straw under varying temperatures (180 to 300 °C) and durations (2 to 6 h) in a closed batch reactor. PAHs were quantified via gas chromatography-mass spectrometry (GC-MS) with deuterated internal standards. Results revealed that total PAHs concentrations increased by 409%, 66.5%, and 68.3% at 180 °C, 210 °C, and 240 °C (4 h and 2 h), respectively, attributed to intensified dehydration and aromatization reactions under subcritical conditions. Conversely, PAHs levels decreased by 80.4% and 78.1% at 270 °C and 300 °C (4 h and 2 h), likely due to thermal cracking of PAHs macromolecules into low-molecular-weight fragments. Prolonged treatment (6 h and 4 h) reduced PAHs by 62.9 to 70.8% at ≤240 °C, suggesting oxidative degradation pathways dominate over pyrolysis under extended residence time. Mechanistic analysis indicated that optimizing HTC at 270 °C for 4 h achieves a critical balance between carbonization efficiency and PAHs suppression, providing a feasible strategy to mitigate ecotoxicological risks of hydrothermal carbon in soil remediation.

Plastic waste is increasing year by year, and its non-degradable nature is causing great damage to the environment. Bamboo is an environmentally friendly and sustainable material. Flattened bamboo green slices offer an alternative solution to plastic hangers due to their excellent bending-mechanical properties. This study elaborates a production technology for flattened bamboo green hangers (FBGH), as well as the status changes of bamboo and related quality issues during the production process. To reveal patterns of bamboo performance variation throughout the bamboo hanger processing, this study analyzes the temperature, moisture content, and thickness changes of bamboo during production. Additionally, key quality issues in the process include cracking, thickness uniformity, and paint film performance. The results indicate that the main quality issues were cracking and thickness uniformity of bamboo green slice. The splitting process significantly affected the thickness uniformity of the bamboo green slice. The cracking of flattened bamboo green slices was most occurred in the splitting, cold pressing, and drying processes. Optimizing the management of the process, improving slicing equipment, minimizing the time between slicing and cold pressing, and adjusting lacquer film process parameters can enhance bamboo processing performance.

Furfurylation expands the value of wood and wood-based products in construction and engineering applications by improving its dimensional stability and lowering its moisture absorption. However, the traditional liquid phase vacuum and pressure impregnation (VPI) process faces some problems and shortcomings in industrial application, such as excessive consumption of modifiers, and inducing wood drying defects. To avoid these inherent shortcomings, a novel furfurylation method based on solution quantitative adsorption (SQA) was first applied in this study to improve the properties of wood. The results showed that the SQA furfurylation could achieve the precise modification of cell wall and avoid the deposition of furfuryl alcohol (FA) resin in the cell cavities. The scanning electron microscopy and nanoindentation results showed the preparation of ultra-stable wood materials (ASE > 70%) with low FA resin load (weight percent gain of about 20%) and high FA utilization. In addition, the SQA furfurylation could lead to the distribution of FA resin in the interior of wood, thus improving the physical properties of wood without altering the overall mechanical properties.

The cellulase RuCel224, derived from the rumen metagenome, was successfully expressed in Escherichia coli BL21(DE3), with a molecular weight of ~43 kDa, as confirmed by sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. Substrate specificity assays revealed the highest activity against sodium carboxymethyl cellulose (CMC-Na) (0.861 ± 0.011 U/mg), followed by wheat straw xylan (0.150 ± 0.050 U/mg). RuCel224 exhibited optimal activity at pH 5.0 and 35 °C, retaining over 70% activity between pH 5.0 and 7.0 and 80% activity within the temperature range of 20 to 40 °C. Thermal stability tests showed that RuCel224 retained 80% activity after 30 min at 50 °C. Metal ion analysis demonstrated that Mn²⁺ significantly enhanced RuCel224 activity by 68.5% and 83.1% at 1 mM and 5 mM concentrations, respectively. Hydrolysis efficiency on lignocellulosic substrates revealed the highest reducing sugar release from corn stalk (206.21 ± 19.11 μg/mL), followed by wheat bran (106.63 ± 20.08 μg/mL) and rapeseed straw (93.83 ± 3.57 μg/mL). Overall, RuCel224 is a highly versatile cellulase under mild conditions, demonstrating strong adaptability to agricultural residues. Its superior performance on corn stalk highlights its potential for bioethanol production and other biomass valorization processes.

The preparation of biodegradable wood plastic composites using polylactic acid (PLA) as the matrix and plant flours as the reinforcing phase aligns with the principles of sustainable development. However, there is a large polarity difference and poor compatibility between PLA and plant flours. To improve the performance of PLA/bamboo flour (BF) composites and simplify the process, this study modified PLA using glycidyl methacrylate (GMA), methacrylic acid (MAA), and maleic anhydride (MAH) as reactive compatibilizers. Composites were prepared from the modified PLA and BF using the hot-pressing method. The results indicated that all three reactive compatibilizers increased the polarity and surface free energy of PLA. GMA, MAA, and MAH were successfully grafted onto the PLA molecular chain, resulting in the formation of PLA-g-GMA, PLA-g-MAA, and PLA-g-MAH graft copolymers. In addition, the interfacial compatibility between PLA-g-GMA and BF was the best, and the PLA-g-GMA/BF composite had the lowest 24 h water absorption (2.17%). Furthermore, the PLA-g-GMA/BF composite showed the highest bending, tensile and impact strengths of 33.3 MPa, 14.7 MPa, and 1.33 kJ/m², respectively, which were 63.8%, 104.9% and 4.7% higher than those of untreated PLA/BF composites, respectively.

Discarded apple tree branches from Yantai, China, were pyrolyzed at 300 to 700 °C with holding times (0 to 120 min) to optimize biochar production parameters. Results showed that compared to 300 °C, increasing pyrolysis temperature from 400 to 700 °C (0 min holding) enhanced fixed carbon content 1.39 to 8.30%, carbon content by 16.31 to 28.84%, while reducing C/H ratios 18.29 to 66.33%. When holding time extended from 60 to 120 min across temperatures, fixed carbon content increased 0.31 to 2.56% below 600 °C but showed minimal gains at higher temperatures. Carbon content changes became negligible (≤ 0.69%) above 500 °C with extended holding. Considering both quality and yield, 600 °C pyrolysis temperature with 60 min holding time was identified as the optimal condition for producing biochar with enhanced carbon stability and resource utilization efficiency. This study provided scientific support for converting fruit tree waste into functional carbon materials through controlled pyrolysis processes.

Through field investigations and field experiments under different modes, the local cost composition and sources of income of agricultural straw carbonization and returning to the field in Xiangfen County, China, were analyzed, and an economic evaluation was carried out. The results showed that the preparation cost of biochar at the county scale was ¥ 1107/t, and it could be reduced to ¥ 507/t after excluding the straw cost. When considering only the income from yield increase, it is difficult to achieve profitability in both the mode of returning the field in batches with equal amounts and the mode of returning the field with a large dose at one time. However, when considering the combined income from yield increase, carbon sequestration, and emission reduction, the annual profit could reach up to ¥ 269/ha. If the straw is owned by farmers (the straw cost is not included), the highest annual income can reach ¥ 1241/ha. Although the upfront cost of agricultural straw carbonization and returning to the field is relatively high, in the long run, it has significant environmental benefits and economic potential in terms of increasing yields, sequestering carbon and reducing the use of chemical fertilizers.

This study evaluated the individual and combined effects of four additives—nano-silica, cationic polyacrylamide, cationic starch, and long fibers—on paper production from recycled white pulp. Various combinations were tested with long fiber pulp (0%, 5%, 10%, and 15%) and different percentages of additives (nano-silica at 3% and 6%; cationic starch at 0.75% and 1.5%; cationic polyacrylamide at 0.07% and 0.15%). Fourteen different groups with a basis weight of 127 gsm were prepared and analyzed for their physical, mechanical, and microstructural properties. Results showed that the additives significantly impacted the properties of the paper. The highest smoothness was achieved with the combination of nano-silica and polyacrylamide, enhancing surface printability. However, the introduction of long fibers increased air resistance and decreased water absorbency, which could pose challenges in printing and machine operation. Maximum tensile and tear strength were observed in sheets with 15% long fiber pulp. Additionally, independent applications of 0.75% and 1.5% cationic starch also improved these properties. Electron microscopy revealed fewer defects in papers treated with nano-silica, though this may negatively affect water absorbency.

To keep consumers from the hazard of exposure to mycotoxins and meet the allowed limits, numerous physical and chemical approaches for eliminating Ochratoxin A (OTA) and Zearalenone (ZEN) have been studied. Enzymes technology, including carboxypeptidase and amidohydrolase, were evaluated on their ability to degrade OTA and ZEN. Two fungi, namely Aspergillus ochraceus and Fusarium graminearum, were isolated with their mycotoxins OTA and ZEN from contaminated yellow corn grains. Carboxypeptidase at 0.50 and 0.75 U/mL caused 33.3 and 57.7% degradation of OTA, and 27.1 and 57.2% degradation of ZEN, respectively. Amidohydrolase at 0.50 and 0.75 U/mL caused 68.0 and 76.9% degradation of OTA, and 26.7 and 53.7% degradation of ZEN, respectively. This study investigated the molecular docking interactions of carboxypeptidase (PDB ID: 3CPA) and amidohydrolase (PDB ID: 1QRE) with OTA and ZEN. Docking scores (S) and energy terms (E_conf, E_place, E_score1, E_refine, E_score2) were calculated to evaluate binding affinities. The OTA exhibited stronger docking scores (-6.00058 to -5.0568) compared to ZEN (-5.37388 to -4.4574), indicating higher thermodynamic stability. Key interactions, such as hydrogen bonds (H-donor/acceptor) and π-based interactions (H-pi/pi-H), were identified between ligands and active-site residues (e.g., ASN 185, LYS 51, and GLU 196).

While public reports exist about hardwood log and lumber prices, sawmills’ operating costs are proprietary, and few records are publicly available. Operating costs make up a considerable share of a sawmill’s cost structure and are, therefore, crucial for understanding the fiscal health of a given operation. Using the assumption that today’s depressed lumber and residue markets result in sawmills, on average, making no profit and incurring no loss, this study estimated operation costs of a hypothetical 4, 8, and 12 MMBF production hardwood sawmill in the eastern United States producing red oak lumber. Using this knowledge and the Log Recovery Analysis Tool (LORCAT), this study found that a sawmill’s financial well-being is highly dependent on hardwood log and operating costs as well as lumber prices. A 0.1% change in any of these factors will lead to a statistically significant change in profit for a sawmill. For example, with a 12 MMBF/year production sawmill, a 0.1% increase in operating cost would reduce profit by $4,510 but would increase profit $4,536 with an operating cost decrease of 0.1%. Similar observations can be made for log cost while lumber prices contribute even more to the volatility of the financial well-being of a sawmill.