Kinetic studies on oil extraction and biodiesel production from underutilized Annona squamosa seeds

The present investigation involves the production of biodiesel from non-edible Annona squamosa oil. Oil extraction has been done using aqueous HCl, H2SO4, and H3PO4 solutions with hexane at various temperatures. The optimum acid concentration is 20 wt.% H2SO4 containing hexane with the maximum oil yield of 28.5%. The reaction order has been found to be first-order kinetics and the activation energy is 44.054 kJ mol−1. Solid acid catalyst prepared by impregnation with phosphoric acid has proved to be an efficient catalyst for the transesterification process. An optimum conversion of 85% has been achieved at 65 °C; methanol-oil molar ratio 18:1; 5 wt.% catalyst. The conversion of triglycerides into methyl esters obeys the first-order mechanism and Ea = 9.042 kJ mol−1. Physico-chemical characteristics have been determined as per American Oil Chemists Society (AOCS) methods and the fuel properties complied the limits prescribed in the ASTM D6751 standards.