The biodiesel yield obtained via a two stage process of oil extraction
followed by transesterification was compared with that obtained by simultaneous
oil extraction and transesterification, a single stage process as shown in Fig. 3 for Spirulina and pondwater algae. The biodiesel yield
was expressed in the terms of relative weight of biodiesel obtained to
that of oil present in algae biomass. It was observed that the single
stage process resulted in higher biodiesel yield compared to two stage
process. Comparing the effect of different solvents on the biodiesel
yield, hexane was observed to give higher yield than chloroform. Hexane
being more non-polar as compared to chloroform, lipids get more
effectively dissolved in hexane than in chloroform (‘Like dissolves like’
rule). Drastic reduction in biodiesel yield was observed when no solvent
was used indicating that solvent is necessary for biodiesel production.
Similar trends were obtained both for Spirulina and pond water algae.
The maximum yield of pond water algae biodiesel and Spirulina algae
biodiesel obtained using hexane in a single stage process was 74.60%
and 79.50% respectively