In this study, sol-gel and zeolite-based catalysts were prepared for the conversion of glucose to lactic acid under hydrothermal conditions and their activities were investigated. SiO2-supported catalysts containing different metal structures, such as Al, Fe, Cr, Sn, and Zn representing Lewis acid structures, were synthesized by sol-gel method. Beta H zeolite and USY H zeolite, as well as Sn-USY and Zn-USY zeolites, were used as zeolite catalysts. X-ray diffraction, Brunauer-Emmett-Teller surface analysis, and scanning electron microscopy analyses were performed to characterize the highly active Zn/SiO2 and USY zeolite catalysts. The highest lactic acid yield of 34.8% was obtained with the Zn/SiO2 catalyst among the SiO2-supported sol-gel catalysts at 180 degrees C for 2 h under 3 MPa N2 pressure. Among the zeolite catalysts, the highest lactic acid yields of 48.3% and 43.8% were obtained with the USY H zeolite and the Zn-USY zeolite catalysts, respectively.
Green coconut waste was subjected to different fractionation methods to obtain integrated lignin nanoparticles and cellulosic ethanol. Pretreatment with gradual addition of dilute sulfuric acid provided a higher structural hemicellulose precursor yield (68.2%). Alkaline treatment resulted in the highest extraction and recovery of lignin from coconut waste, at 79.5% and 25.3%, respectively. Separate hydrolysis and fermentation indicated that slow acid addition followed by alkaline treatment rendered the coconut biomass more susceptible to enzymatic digestion, achieving sugar yields above 60% and an ethanol yield of 0.48 (w/w). Alkaline lignin from coconut fibers was successfully converted into nanometric structures of spherical conformation (& Oslash; = 80-600 nm) with a high degree of uniformity, homogeneous dispersion, and colloidal stability, with weight yields of 30% to 50%. Thus, utilizing coconut waste to obtain cellulosic ethanol and lignin nanoparticles is feasible and results in value-added products and an environmentally sustainable alternative to waste disposal.
Anaerobic digestion can be an alternative method for treating wastewater from second-generation biorefineries while simultaneously producing biogas. However, the feasibility of the process and key operational parameters by which wastewater produced in lignocellulosic biorefineries affects reactor performance remain poorly understood. This study evaluated the thermophilic anaerobic treatment of wastewater from the hydrothermal biomass pretreatment stream of a lignocellulosic biorefinery. Reactor performance, effects of wastewater on methanogenic activity, and microbial community composition were examined. A maximum methane production rate of 0.4 normal L CH4 L-1 per day and a yield of 175 normal L CH4 kg-1 chemical oxygen demand (COD) were obtained at an organic loading rate of 8.5 kg COD m-3 per day and 0.75 days of hydraulic retention time. The lignocellulosic wastewater exhibited low acetoclastic-specific methanogenic activity (0.37 g CH4-COD g-1 volatile solids per day), resulting in suboptimal methane reactor performance despite its relatively high soluble COD content. The wastewater imposes selective pressure with a specialized microbiota comprising bacteria from the extremophile order MSBL9, Fervidobacterium, Candidatus Caldatribacterium, Oscillospirales, and Acetomicrobium, as well as Methanosarcina thermophila and Methanothermobacter archaea. Despite the adaptation and high specialization of the microbial community, wastewater from advanced biorefineries exhibited inhibitory properties that adversely affected methanogenic activity.
The uncontrolled discharge of synthetic azo dyes into aquatic environments poses a serious threat to ecosystem integrity and public health, necessitating the development of sustainable and efficient remediation strategies. In this study, a novel bioderived hydrogel composite (PAA@LP) was synthesized by integrating waste lemon peel (LP) biomass into a polyacrylamide network using free-radical polymerization and evaluated for the adsorption of the anionic dye Sunset Yellow FCF (SY) from aqueous solutions. Structural and surface characterizations using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) spectroscopy confirmed the successful incorporation of LP into the polymer matrix and revealed a porous, functionalized architecture rich in hydroxyl, carboxyl, and amide groups. Batch adsorption experiments demonstrated that SY removal was highly pH dependent, with maximum adsorption occurring under acidic conditions (pH 2-3), consistent with the composite's point of zero charge (pHp zc = 3.87). Equilibrium data were best described by the Langmuir isotherm model (R 2 = 0.983), indicating monolayer adsorption with a maximum adsorption capacity of 89.5 mg g-1. Kinetic analysis showed that the adsorption process followed a pseudo-first-order model, suggesting surface-controlled chemisorption, and intraparticle diffusion contributed as a secondary rate-limiting step. Thermodynamic parameters revealed that the adsorption process was spontaneous Delta(G degrees = -4.58 to -11.8 kJ mol-1) and endothermic Delta(H degrees = +53 kJ mol-1), with increased randomness at the solid-liquid interface Delta(S degrees = +207 J mol-1 K-1). Regeneration studies indicated that the PAA@LP composite retained substantial adsorption performance over three adsorption-desorption cycles, achieving up to 62% desorption efficiency using 0.1 mmol dm-3 HCl. The adsorption mechanism was governed by a combination of electrostatic attraction, hydrogen bonding, pi-pi interactions, and partial chemisorption between the dye molecules and functional groups of the composite. Overall, this work demonstrates an effective waste-to-resource strategy by valorizing LP biomass into a low-cost, reusable, and environmentally benign hydrogel adsorbent. The developed PAA@LP composite shows strong potential for sustainable treatment of dye-contaminated wastewater and contributes to the advancement of circular bioeconomy-oriented water remediation technologies.
Sustainable intensification of the rice-wheat cropping system (RWCS) is essential to address increasing weed pressure, soil carbon loss, rising energy demand and declining farm profitability under long-term conventional management on the Indo-Gangetic Plain. Therefore, this study assessed the ninth year (2023-2024) impact of different crop establishment methods in a long-term field experiment initiated in 2015 in eastern Uttar Pradesh, India. The results demonstrated that, compared with conventional practice (CE1), full conservation agriculture (CA) (CE6) significantly reduced weed density and biomass in both rice and wheat, with stronger suppression at later growth stages. These gains contributed to 34.6% higher rice yield (4.78 t ha-1) and 17.9% higher wheat yield (4.81 t ha-1). Also, CA improved soil physical and chemical properties by lowering bulk density and increasing soil organic carbon, available nitrogen, phosphorus, and potassium by approximately 34, 34.5, 51.7, and 7%, respectively. Carbon stock increased to 23.36 Mg C ha-1, corresponding to 85.74 Mg CO2e ha-1 and a net sequestration of 18.40 Mg CO2e ha. Further, energy analysis showed that CE6 reduced input energy by 27.3% while increasing output energy, leading to 49% higher net energy and improved energy-use efficiency, leading to lower production costs and higher net returns and benefit-cost ratios. Partial CA systems also delivered measurable agronomic and economic benefits, indicating feasible transition pathways for farmers. Overall, the study demonstrates that long-term CA strengthens weed suppression, soil carbon sequestration, energy efficiency, and crop productivity, supporting climate-resilient and sustainable cropping systems.
