Synthesis of magnetite using petai (Parkia speciosa) peel extract with ultrasonic waves as reusable catalysts for biodiesel production from waste frying oil

Magnetite synthesis using petai (Parkia speciosa) peel extract using the sonochemical method (Fe3O4-PPE) has been successfully carried out. Fe3O4-PPE is applied as a catalyst in biodiesel production. This study aimed to determine the physical and chemical characteristics of Fe3O4-PPE and its ability as a reusable catalyst in biodiesel production using waste frying oil as the primary raw material. Characterization of Fe3O4-PPE was carried out using FTIR, XRD, and PSA instruments. Biodiesel was produced in 3 reaction cycles with the same Fe3O4-PPE catalyst. The results of the FTIR characterization showed that the Fe3O4-PPE catalyst had Fe-O bonds from Fe3O4 and -OH phenolic groups, -C-O, -C=C aromatic compounds derived from petai peel extract. The crystal size of the Fe3O4-PPE catalyst based on the results of calculations using Debye-Scherrer from the XRD chromatogram is 9.41 nm. The particle size of the Fe3O4-PPE catalyst based on analysis using PSA was divided into three groups, namely, 5.4 nm, 195 nm, and 2702.6 nm. Fe3O4-PPE was successfully used as a reusable catalyst for three cycles of biodiesel production using waste frying oil as raw material. The characteristics of Fe3O4-PPE before and after being used as a catalyst did not change. Based on GC-MS analysis, the fatty acid methyl ester (FAME) composition of biodiesel is palmitic acid and oleic acid.