Optimized recovery of transesterifiable oil from industrial fats, oil, and grease (FOG) esterified with H2SO4 catalyst extracted from discarded lead-acid batteries

The increasing demand for energy and the growing concerns over environmental issues have prompted researchers to explore alternative energy sources, such as biodiesel. Biodiesel is a renewable, non-toxic, and biodegradable fuel derived from vegetable oils, animal fats, and waste oils, making it a sustainable energy source. This study aimed to optimize the recovery of transesterifiable oil from industrial fats, oil, and grease (FOG) esterified with an H 2 SO 4 catalyst extracted from discarded lead-acid batteries. In recovering the oil, a thermal process was employed to extract it from the raw FOG, followed by esterification with sulfuric acid derived from lead-acid batteries. Central composite design (CCD) of the response surface methodology (RSM) was used to optimize the operating variables, including methanol-to-oil ratio, catalyst loading, temperature, and reaction time. The optimized conditions resulted in a 96.47 ± 0.68% transesterifiable oil recovery using an 8:1 methanol-to-oil molar ratio, 8 v% of H 2 SO 4 catalyst, and 4 h of reaction time at 50 °C. The recovered oil was characterized for various parameters: density, pH, free fatty acid (FFA) level, fatty acid profile, and functional groups. The results indicated that the recovered oil could be a suitable raw material for biodiesel production, as it possessed desirable properties such as low FFA content and a high percentage of unsaturated fatty acids.