Volume 21 Issue 4

Hydrothermal liquefaction (HTL) uses compressed water at high temperatures (≥250 °C) to convert wet biomass into a synthetic crude oil (bio-crude). Here, sugarcane bagasse was treated in batch mode using water, ethanol, and a water+ethanol (1:1, w/w) mixture at a 1:9 biomass-to-solvent mass ratio to evaluate the effects of solvent, non-isothermal heating, temperature (180, 210, and 240 °C), and holding time at the setpoint temperature (0 to 60 min) on product distribution under pre-HTL conditions. With water at 240 °C and 60 min holding time, solid recovery was 48% and non-volatile liquor products were 16%. Under the same conditions, the water+ethanol mixture improved fractionation, yielding the highest extraction (35%) and the lowest solid recovery (36%). Ethanol addition inhibited humins formation and favored lignin and hemicellulose fractionation (solid recoveries of 27% and 1% at 240 °C and 60 min), while 56% of glucans remained in the residual solids. Under the best sugar recovery treatment (water, 180 °C, 0 min), 62% of hemicelluloses were recovered in the liquor at a 1:6 mono-to-oligosaccharide ratio. Under harsher conditions, even in the presence of ethanol, slow heating promoted depolymerization but also substantial sugar degradation, with acetic acid being identified as the main component of liquid streams.

The combined effects of grain orientation and CNC end milling parameters on wood surface quality remain poorly understood. This study investigated the surface quality of tangential oak during frontal milling and radial oak during peripheral milling using straight-flute end mill tools with diameters of 8 and 10 mm, four stepover values (30%, 50%, 70%, and 90% of the tool diameter), and two cutting depths (1 and 3 mm). Surface quality was evaluated through roughness parameters and profiles, microscopic observations, and compared with reference surfaces obtained by shaving and P150 sanding. ANOVA revealed that stepover is the primary factor governing roughness, followed by tool diameter, while cutting depth had no statistically significant impact. Increasing the stepover beyond 50% substantially degrades the surface due to severe fiber lifting and tool ridges. The 8 mm tool produced smoother surfaces than 10 mm tool, in both milling operations and at 30% stepover closely approached the ideal shaved baseline. In frontal milling, stepovers of 30% and 50% outperformed sanding, whereas in peripheral milling, only the 8 mm tool yielded superior quality. Utilizing a smaller tool diameter at a low stepover ratio guarantees a finish-ready surface directly from the CNC machine.

Bio-based polyols derived from lignocellulosic biomass have attracted considerable attention as sustainable alternatives to petroleum-based polyols in polyurethane production. In this study, spruce sawdust was liquefied using pretreated crude glycerol (PCG) and pretreated crude glycerol/polyethylene glycol (PCG/PEG) binary solvent systems under acid-catalyzed conditions to produce bio-polyols. The effects of reaction temperature, reaction time, and solvent composition on biomass conversion, hydroxyl number, acid number, and viscosity of the resulting polyols were systematically investigated using response surface methodology (RSM). Liquefaction experiments were conducted at temperatures ranging from 100 to 180 ºC for PCG and 120 to 200 ºC for PCG/PEG mixtures, with reaction times between 40 and 360 min. The results demonstrated that increasing temperature, reaction time, and PEG content significantly enhanced biomass conversion efficiency. Statistical analysis confirmed that temperature and reaction time were the most influential parameters affecting polyol properties and liquefaction performance. The incorporation of PEG improved biomass conversion and reduced viscosity compared with PCG alone. The obtained bio-polyols exhibited physicochemical characteristics within the range generally considered suitable for rigid polyurethane foam polyol formulations, demonstrating the potential of PCG and lignocellulosic waste as sustainable feedstocks for high-value polyurethane materials.

Biogenic synthesis using plant materials provides a sustainable alternative to classical nanoparticle fabrication, minimizing chemical hazards and decreasing energy input. In this study, silver nanoparticles (AgNPs) were prepared using an aqueous extract of Mercurialis annua and characterized. Physicochemical properties of the AgNPs were confirmed using ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared (FTIR) analysis, X-ray diffraction (XRD), and transmission electron microscopy coupled with energy-dispersive X-ray (TEM–EDX), which collectively indicated crystalline, spherical silver nanoparticles stabilized by extract-derived functional groups. Subsequently, the biological activities of both the nanoparticles and the extract were comparatively evaluated using antioxidant tests, including cupric ion reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolic content (TPC), and total flavonoid content (TFC), as well as enzyme inhibition tests targeting α-glucosidase and carbonic anhydrase. Liquid chromatography-mass spectrometry profiling identified 31 phenolic constituents in the extract, with ferulic, caffeic, salicylic, and 4-hydroxybenzoic acids detected in high abundance. Overall, the biosynthesized AgNPs demonstrated higher antioxidant performance and stronger inhibitory effects on both enzymes compared with the crude extract. These results indicate that M. annua-based AgNPs hold considerable promise sustainable and effective bioactive agents for future biomedical and biotechnological applications.

In the context of Kazakhstan’s strategy to achieve carbon neutrality by 2060, assessing transport-related CO₂ emissions associated with imported timber supply has become increasingly important. For Kazakhstan, this issue is particularly relevant for Kazakhstan because its woodworking industry depends heavily on imported timber transported over long distances. The objective of this study was to assess CO₂ emissions generated during the transportation of imported sawn timber to Kazakhstan, through a comparative analysis of transport-related CO₂ emissions under different logistics scenarios and a comparison of logistics scenarios. The study considers three logistics supply scenarios: rail transport, road transport, and a combined scenario (rail transport followed by a road segment). Calculations were based on a distance-oriented model using average emission factors consistent with international databases. One tonne of sawn timber is adopted as the functional unit. The results showed that rail transport provides the lowest emission level (62 kg CO₂/t), whereas road transport generated substantially higher transport-related CO₂ emissions (153 kg CO₂/t). The combined scenario demonstrates an intermediate value (148.5 kg CO₂/t), indicating the substantial influence of the road transport share on total emissions.

Subterranean termites are major biological agents causing wood deterioration in tropical regions. Laboratory bioassays commonly use susceptible reference materials as controls to ensure termite feeding activity; however, information on the long-term variability of such materials remains limited. This study evaluated the variability and repeatability of Hevea brasiliensis (rubberwood) as a control material in laboratory tests involving Coptotermes curvignathus. Data from 27 independent trials conducted between 2016 and 2025 were analysed, with five replicates per trial exposed for four weeks using a standardized Forest Research Institute Malaysia in-house method. The mean density ranged from 0.584 to 0.701 g/cm³, while mean weight loss varied from 3.97% to 17.34%. The coefficients of variation for density, weight loss, and visual rating were 6.40%, 39.73%, and 13.11%, respectively. Weak correlations were observed between density and weight loss (r = 0.108), density and visual rating (r = −0.091), and weight loss and visual rating (r = −0.281). The results indicate that variability in feeding damage was primarily influenced by biological differences among termite colonies rather than wood density. Hevea brasiliensis was confirmed as a consistent and suitable control material for laboratory termite bioassays.

Poplar wood specimens were fabricated via surface swelling pretreatment with NaOH solution combined with a hot-pressing process. The three factors NaOH concentration, hot-pressing temperature, and hot-pressing time were considered relative to shear strength. The optimal process parameters for poplar adhesive-free bonding were surface swelling with 5% NaOH solution, a hot-pressing temperature of 140 ºC, and a hot-pressing time of 60 min. Under these parameters, the shear strength of the prepared specimens’ bonding interface reached 4.87 MPa. Analysis of variance showed that hot-pressing temperature exerted a highly significant effect on shear strength and that temperature was the dominant factor influencing adhesive-free bonding performance. Scanning electron microscopy observations indicated that NaOH solution surface swelling had a notable impact on the adhesive boundary, facilitating the formation of a dense adhesive layer in this area. Furthermore, a distinct phenomenon of molten lignin encapsulating fibers was observed at the bonding interface. As a natural bonding medium, molten lignin effectively enhances the bonding between fibers, thereby improving the adhesive-free bonding strength of poplar wood. Hemicellulose underwent substantial degradation, while no significant degradation was observed in the skeletal structure of lignin. This study provides a theoretical foundation and technical reference for optimizing the poplar wood adhesive-free bonding process.

Expanded polystyrene (EPS), widely used in plastic packaging, poses recycling challenges and contributes to environmental pollution due to its persistence. As an alternative, biopackaging materials were developed using mycelium from Ganoderma lucidum and agave bagasse (Agave tequilana Weber var. azul), a common agro-industrial residue in Jalisco, Mexico. The resulting materials showed a uniform, lightweight structure. SEM analysis confirmed full colonization of agave fibers by mycelium, indicating good cohesion. FTIR spectroscopy suggested intermolecular interactions between the fungal matrix and the lignocellulosic substrate. The material also exhibited hydrophobic behavior, as evidenced by its high water contact angle, indicating a surface with low wettability. In fire tests, the biopackaging burned slowly, emitted white smoke, and exhibited self-extinguishing behavior. Mechanical testing showed that the composites reached maximum force values in the same order of magnitude as EPS. Although flexural strength was slightly lower, the material tolerated greater deformation under comparable loads, indicating improved strain accommodation and resistance to abrupt fracture. Using the LIDS (Life Cycle Design Strategy Wheel), these materials were compared to conventional plastics, demonstrating advantages such as reduced reliance on petroleum-based polymers, valorization of agave waste, and alignment with circular production strategies in the tequila sector.

The techno-economic and environmental performance was assessed for the composting of oil palm empty fruit bunches (EFB) through an aerated bunker composting (ABC) system. The process flowsheet was developed using SuperPro Designer, with process data and operating parameters sourced from prior experimental and industrial studies. Simulation results exhibited agreement with literature data, demonstrating the reliability of the model. The process is potentially able to achieve a 79% reduction in carbon dioxide equivalent (CO₂e) emissions relative to landfilling, underscoring considerable climate mitigation potential. Economic evaluation estimated capital expenditure (CAPEX) at MYR 43.8 million and OPEX at MYR 15.7 million/year, with enriched compost contributing to 73.3% of revenues. The base case yielded a net present value (NPV) of MYR 58.4 million, return on investment (ROI) of 30.5%, and payback of 3.28 years, demonstrating strong feasibility. Scenario analysis revealed that increasing the portion of enriched compost substantially improves profitability, while carbon credit and CAPEX incentives further enhance investment appeal. Sensitivity results highlighted the enriched compost price, annual operating time, and CAPEX as the main determinants of financial performance. Overall, the system provides both substantial environmental benefits and compelling economic viability, offering a scalable pathway for sustainable EFB management.

Heat treatment of Paulownia tomentosa wood was studied relative to the physical and mechanical properties, with a view to expanding the potential fields of use of this species. Several physical properties (density, water absorption after 2 and 24 h, thickness swelling) and mechanical ones (strength and modulus of elasticity in static bending, tensile strength parallel to the gran and Brinell hardness) were evaluated. Most physical and mechanical properties of Paulownia wood were superior in the radial direction, with the exception of tensile strength, regardless of whether the samples were subjected to torrefaction treatment or not. In addition, the water affinity of heat-treated wood decreased significantly, with water absorption after 2 h of immersion reduced by 21% and tangential thickness swelling after 2 h of immersion reduced by 36.6%. The static flexural modulus of elasticity decreased by 12.1% at temperature of 160 ºC treatment, by 39.9% for the 180 ºC treatment and by 52.8% for the at temperature of 20 ºC treatment.