Efficient bifunctional catalyst lipase/organophosphonic acid-functionalized silica for biodiesel synthesis by esterification of oleic acid with ethanol

- A novel bifunctional catalyst SG-T-P-LS was successfully developed.
- Esterification of FFA oleic acid on the bifunctional catalyst was investigated.
- Biodiesel synthesis process by esterification of oleic acid was optimized by RSM.
- Optimum parameters were 14.9 wt.% SG-T-P-LS at 28.6 °C and 1.05:1 (molar) ethanol:oleic acid.
- A maximum FFA conversion of 89.94% could be obtained under the optimized conditions.