Converting waste cooking oil into biodiesel using phosphomolybdic acid/clinoptilolite as an innovative green catalyst via electrolysis procedure; optimization by response surface methodology (RSM)

Abstract The present study aims to convert waste cooking oil (WCO) into biodiesel via phosphomolybdic acid (H3PMo12O40, PMA) supported on Clinoptilolite as a novel green acid catalyst through an electrolysis procedure. The prepared catalysts were characterized by XRD, FTIR, FESEM, EDS, Elemental map, and TEM analyses. The effect of four independent variables on biodiesel yield including methanol to oil molar ratio (6:1–14:1), catalyst weight (2–5 wt%), time (3–5 h), and voltage (15–35 V) was optimized and evaluated by the response surface methodology (RSM) employing central composite design (CCD). The maximum value of biodiesel yield was 96% under the optimal conditions, including the methanol to oil molar ratio of 9:1, catalyst weight of 3 wt%, time of 4 h, and voltage of 21 V at room temperature. The catalyst was reused five times with an average yield of ~83.4%. The biodiesel production was confirmed by FTIR and H-NMR analyses, with its chemical and physical characterizations being in agreement with the ASTM standard. In conclusion, the fabricated biodiesel from WCO is an economical and environmentally friendly procedure thanks to cheap primary feedstock and catalyst.