Efficient biodiesel production assisted by electrolysis using a magnetic lignin-based heterogeneous acid catalyst Fe3O4-LS/100-Al

Conventional biodiesel production relies on external heating, requiring high temperatures and strict control over system water content. This work prepared a magnetic lignin-based heterogeneous acid catalyst Fe 3 O 4 -LS/100-Al using sodium lignosulfonate as support via co-precipitation and impregnation, with Lewis acid sites, and applied it in electrolysis-assisted esterification for biodiesel. The catalyst showed a specific surface area of 115.63 m 2 /g and saturation magnetization of 29.98 emu/g, enabling efficient acid loading and rapid magnetic separation. Under RSM-optimized conditions (catalyst of 6.8 wt%, MOAMR of 12.5:1, voltage of 45.4 V, water content of 4.7 wt%), oleic acid conversion reached 95.25%. Low activation energy (36.04 kJ/mol) confirmed high catalytic activity, and 71.38% conversion was retained after seven cycles. Results prove electrolysis assistance enables efficient, ambient-temperature biodiesel synthesis.