Active sites engineered biomass-carbon as a catalyst for biodiesel production: Process optimization using RSM and life cycle assessment

Abstract

Herein, we aimed at the production of porous biochar by simultaneous activation-graphitization. The active sites engineered biochar catalyst was functionalized using 4-DBS, which possessed a high surface area, and sulfur content of 1196.13 m2 g−1 and 1.9 mmol g−1, respectively. We extensively analyzed the catalyst using various techniques such as XRD, FTIR, TGA, NH3-TPD, SEM-EDS, TEM, BET, and XPS. We used this catalyst to optimize Jatropha curcas oil (JCO) transesterification, achieving a 97.1 ± 0.4% yield with the RSM-CCD method. Kinetic studies showed pseudo-first-order kinetics, and thermodynamics indicated an endothermic, nonspontaneous process.. A life cycle assessment was conducted to assess the environmental impacts of producing biodiesel from JCO, using 1 kg of biodiesel as the reference unit. The findings revealed that the total abiotic depletion of fossil resources throughout the entire biodiesel production process amounted to 52.1 MJ, the global warming potential was equivalent to 3.17 kg of CO2 emissions, the acidification potential was comparable to 0.027 kg of SO2 emissions, and the eutrophication potential was 0.016 kg of PO43−, human toxicity level 1.89 kg 1,4-DP eq and freshwater ecotoxicity to kg 1,4-DP equivalent for every 1 kg of biodiesel manufactured. The estimated cost of biodiesel produced was 1.3 USD ($) per kg, which mainly attributed to the high reusability of catalyst (82.5 ± 0.4% yield in 7th cycle), indicating high commercial applicability. Finally, the study proposes future recommendations based on identified gaps in the literature through innovative bibliometric analysis.