Valorization of oleochemical waste as feedstock for biodiesel production using industrial ash waste magnetic-based catalyst

Biodiesel was synthesized directly from waste oils in a single-step process, eliminating the need for pre-treatment. A solid base catalyst was successfully synthesized using Spent Bleaching Earth (SBE) as the primary support material through a wet impregnation method. The synthesis process involved the incorporation of potassium hydroxide (KOH) and ammonium ferrous sulfate hexahydrate (NH4)2Fe(SO4)2.6 h2O) to enhance catalytic performance. The mixture was magnetized under an air atmosphere in a furnace. Under optimized conditions, a transesterification process employing 0.15 g of the synthesized magnetic K2SO4/Fe2O3-SBE700 catalyst resulted in a 78.47% biodiesel yield from bleached oil. The process utilized a 1:22 ratio of oil to methanol and was conducted at 80 degrees C for 2 hours. The catalyst demonstrated excellent catalytic activity and could be easily recovered through magnetic separation using K2SO4/Fe2O3-SBE700. Physicochemical properties of the catalyst, bleached oil, and biodiesel were analyzed using techniques such as BET, FESEM-EDX, TGA, and XRD. XRD analysis revealed sharp and well-defined peaks indicating the presence of crystalline structures characteristic of K2SO4 (arcanite) and Fe2O3 (hematite). This study effectively utilized the inorganic components within Spent Bleaching Earth (SBE) and its associated oil for direct biodiesel production, thus minimizing waste generation.