Valorization of palm oil soap stock waste toward for biodiesel production: Process optimization under zero waste concept

Palm oil soap stock (POSS) was recycled from bio-waste to bio-fuel. Firstly, POSS was converted through acidification to be acidified POSS (APOSS) coupled with solvent extraction. APOSS with a high content of free fatty acids (FFAs) (90.94%) was obtained. Subsequently, the FFAs in APOSS were converted to biodiesel via esterification, catalyzed by immobilized alginate-polyvinyl alcohol (ALG-PVA) lipase. The key factors affecting the reaction, such as the temperature (30-50 degrees C), methanol to FFA molar ratio (2:1 to 4:1), and agitation rate (150-250 rpm) were optimized by statistical response surface methodology (RSM). The highest biodiesel yield was achieved with a reaction temperature of 40 degrees C, methanol/FFA molar ratio of 3:1, and 200 rpm agitation rate, as the optimal conditions. Furthermore, the biocatalyst can be reused up to 16 cycles. Interestingly, the alter-native biodiesel production process reported herein promotes zero waste from the palm oil refinery process.

Automated summary

The study recycled palm oil soap stock waste into bio-fuel, producing biodiesel through acidification and esterification reactions, achieving a zero waste production process.