This research explores the potential of activated carbon (AC), produced from corncobs, for eliminating dissolved hexavalent chromium and divalent nickel. SEM analysis revealed a rough, textured surface on the corncob-derived activated carbon with well-defined pores and crevices, indicating the successful formation of activated carbon. We employed X-ray diffraction to confirm the presence of crystalline graphite within the carbon structure, suggesting effective alignment of carbon atoms. Utilizing Design of Experiments (DOE), we optimized adsorption conditions for enhanced removal efficiency. Our findings reveal that under optimized conditions, the activated carbon achieved a maximum removal of 99.2% for Chromium (VI) at 105 min, pH 2, temperature of 37°C, an initial chromium concentration of 37.2 ppm, and an AC dosage of 0.289 g. Similarly, Nickel (II) removal reached 98.7% at pH 12, temperature of 40°C, a starting concentration of 31 ppm, and an adsorbent amount of 0.94 g. The adsorption kinetics of both metals followed a pseudo-second-order mechanism, suggesting chemisorption as the controlling mechanism. The adsorption data was best described by the Langmuir isotherm, indicating a monolayer coverage of metal ions on the adsorbent surface. These results demonstrate the potential of corncob-derived AC as a promising waste material for removing heavy metal from wastewater.

The quality of water is significantly impacted by the presence of Cr⁶⁺ and Ni²⁺ ions. This study investigates the effectiveness of a flow-by porous graphite electrode cell in removing these contaminants from simulated industrial wastewater. We explore the impact of various factors on the removal process, demonstrating the method's potential for efficient removal. The initial concentration of nickel and chromium ions (20 to 80 mg/l and 20 to 100 mg/l, respectively), the feed flow rate (0.28 to 1.11 ml/s), current density (0.2 to 2.25 mA/cm²) and pH all influence the removal rate and efficiency. A higher feed flow rate negatively affects the removal efficiency of both Ni²⁺ and Cr⁶⁺ ions. Nickel removal efficiency decreased by 34.9% at 20 ppm and 26% at 80 ppm, representing the highest and lowest reductions in efficiency, respectively. Chromium removal efficiency decreased by 19% at 100 ppm and 6.5% at 50 ppm, indicating the highest and lowest reductions in efficiency, respectively, under the same flow rate change. Under optimal conditions, the removal efficiency for Ni²⁺ was 99.47% after 15 min of operation at a current density of 1.96 mA/cm², a flow rate of 0.28 ml/s, and a pH of 8 and the removal efficiency for Cr⁶⁺ was 99.97% after 10 min of operation at a current density of 2.25 mA/cm², a flow rate of 0.28 ml/s, and a pH of 2. The flow-through porous electrode system achieves efficient heavy metal removal with operating costs of 0.24 USD/m³ for nickel and 0.38 USD/m³ for chromium at optimal conditions.

Background: This study explores a sustainable method for biofuel production from leather tanning waste (LTW) using a novel single-step, catalyst-free supercritical methanolysis (SpCM) process. Traditional biodiesel production methods often require catalysts and involve complex purification steps, whereas this study aims to optimize process parameters to enhance biodiesel yield while reducing energy and material consumption. Methods: The research employed a Box–Behnken experimental design integrated with response surface modeling (RSM) to optimize key process variables, including alcohol-to-LTW molar ratio (r _mo), operating temperature, pressure, and reaction duration. The produced biodiesel was characterized according to EN 14214 standards. Kinetic studies of the transesterification reaction were conducted, and a robust reactor model was developed in Aspen Plus to estimate the kinetic parameters. Results: The activation energy (E _a) and pre-exponential factor (A) were determined to be 45.085 kJ/mol and 86.24 s⁻¹, respectively, with a rate constant (k) of 0.0098 s⁻¹ at an optimized temperature of 322.938 °C. The optimized conditions using RSM achieved a biodiesel yield of 89.35% at an r _mo of 32.35:1, a temperature of 322.938 °C, a pressure of 219.073 bar, and a reaction time of 14.26 min. The simulation model under the same conditions predicted a biodiesel yield of 89.49%, demonstrating excellent agreement with experimental results, with a maximum error of 0.54%. Conclusions: This study presents a comprehensive approach to biodiesel production from LTW, demonstrating an efficient and sustainable alternative to conventional methods. The optimized catalyst-free SpCM process minimizes energy input and material usage while achieving high biodiesel yields. These findings contribute to waste valorization in the leather industry and support environmental sustainability efforts. Graphical

Due to the generation of fat-rich residues from the leather industry, these fat-rich residues are considered a promising feedstock for waste valorization into biofuel applications. Limed flashing waste (LFW), collected from Badr City, Egypt, was subjected to different multi-purpose pretreatment steps, including delimiting, drying, chopping, Soxhlet extraction, and degumming to recover oil. The recovered oil was then transesterified with methanol using commercial CaO as a catalyst. Multi-variable regression modeling was applied to optimize the triglyceride conversion into biodiesel. The optimized reaction conversion yielded a conversion of 97.74% achieved under a methanol-to-oil ratio of 8.93:1, 5.74% w/w catalyst loading, 63.4°C reaction temperature, agitation speed at 300 rpm, and 3 hours of reaction time. GC-MS and FT-IR analysis both confirm the conversion of LFW into biodiesel, highlighting its suitability and feasibility as an alternative source for sustainable energy. It was demonstrated that LFW produced from the leather industry, whose handling and discarding are challenging, can be converted into biofuel. Thereby contributing to waste management and energy demands.

Thermal control represents one of the most important parameters influencing the safety and reliability of lithium-ion batteries, especially at high rates required for modern electric vehicles. The present paper investigates the thermal and electrothermal performance of a lithium iron phosphate (LiFePO₄) battery pack using a combination of experimental, statistical, and numerical methods. The 8S5P module was assembled and examined under load tests of 200, 400, and 600 W with and without active air-based cooling. The findings indicate that cooling reduced cell surface temperature by up to 10 °C and extended discharge time by 7–16% under various load conditions, emphasizing the effect of thermal management on battery performance and safety. In order to more systematically investigate the impact of ambient temperature and load, a RSM study with a central composite design (CCD; 13 runs) was performed, resulting in two very significant quadratic models (R² > 0.98) for peak temperature and discharge duration prediction. The optimum conditions are estimated at a 200 W load and an ambient temperature of 20 °C. Based on experimentally determined parameters, a finite-element simulation model was established, and its predictions agreed well with the measured results, which verified the analysis. Integrating measurements, statistical modeling, and simulation provides a tri-phase methodology to date for determining and optimizing battery performance under the electrothermal dynamics of varied environments.