Green synthesis of biodiesel from magnetic basic biochar derived from Amazonian murici residual biomass: Optimization, kinetic, thermodynamic, and environmental studies

There is a growing need for sustainable catalysts in biodiesel production, however, efficient and low-cost alternatives derived from agro-industrial residues remain limited. This study addresses this gap by exploring murici biochar as a potential source for catalytic development. A basic magnetic catalyst, based on biochar from an Amazonian agro-industrial residue and consisting of sodium impregnated in murici biochar with cobalt ferrite as the magnetic phase, was produced for application in the transesterification reaction of soybean oil. The catalyst was synthesized by wet impregnation with different sodium concentrations to determine the optimal concentration of active phase in the synthesis process. The catalyst demonstrated the best performance and was characterized by TGA, XRD, FT-IR, SEM, EDS, and VSM. A central face-centered composite design was used in the development of a mathematical model for the prediction of ester content. The biodiesel obtained in the optimized reaction conditions of temperature of 90 °C, reaction time of 1.4 h, methanol:oil (MeOH:oil) molar ratio of 17:1, and catalyst concentration of 7 % obtained ester content of 97.11 % and presented physicochemical properties according to the limits established in the ASTM D6751. Moreover, the kinetic and thermodynamic studies revealed that the process follows the pseudo-first order. It also presents an endothermic and not spontaneous character. The green reaction parameters indicate that the reaction using the catalyst is sustainable with low waste generation. Thus, this study show the feasibility of applying the agro-industrial residue in the synthesis of environmentally friendly and low-cost magnetic basic catalysts for the production of biodiesel. [Display omitted] •Agro-industrial waste from Amazonian for synthesis of a new basic magnetic catalyst.•Optimization of transesterification reaction conditions by Response Surface Methodology using FCCD.•The ester content of biodiesel reached 97.11 % under proposed optimum conditions.•Catalyst with easy magnetic separation and ester content ≥80 % until the 4th cycle.•Biodiesel production followed a cleaner and more environmentally friendly route.