Surfactant-assisted direct biodiesel production from wet Nannochloropsis occulata by in situ transesterification/reactive extraction

Abstract

This article reports an in situ transesterification/reactive extraction of Nannochloropsis occulata for fatty acid methyl ester (FAME) production using H2SO4, sodium dodecyl sulphate (SDS) plus H2SO4 and zirconium dodecyl sulphate (ZDS). A maximum 67 % FAME yield was produced by ZDS. Effect of inclusion of sodium dodecyl sulphate (SDS) in H2SO4 for FAME enhancement and water tolerance was also studied by hydrating the algae with 10 % - 30 % distilled water (w/w) dry algae. Treatment with SDS in H2SO4 increases the FAME production rate and water tolerance of the process. Inclusion of SDS in H2SO4 produced a maximum 98.3 % FAME yield at 20 % moisture in the algae. The FAME concentration began to diminish only at 30 % moisture in the algae. Furthermore, the presence of a small amount of water in the biomass or methanol increased the lipid extraction efficiency, improving the FAME yield, rather than inhibiting the reaction.

Keywords

• Wet microalgae
• reactive extraction
• biodiesel (Fatty acid methyl ester)
• surfactant
• surfactant catalyst