Microalgal Lipid Extraction and Evaluation of Single-Step Biodiesel Production

Abstract

This work examined solvent extraction of lipid from microalgae for production of renewable biofuels, thereby allowing appropriate selection of solvent and extraction methods. The results of this study revealed that the mixture of chloroform and methanol (C/M) at the ratio of 2:1 (v/v) could extract the highest amount of total lipid from algae, while hexane was found to be a good solvent, concerning the selectivity for nonpolar targeted lipids such as mono-, di- and tri-glycerides. As far as the extraction methods are concerned, applying ultrasound could accelerate the rate of lipid extraction from algae with tough cell walls such as Chlorella vulgaris. On the other hand, ultrasound and microwave assisted extraction techniques added no benefits to the extraction of lipid from powder of Haematococcus pluvialis whose cell wall was previously damaged. Other than lipid extraction, this paper concerns with the development of transesterification process for algal lipid using C. vulgaris as a model system. Here, the effects of the amount of catalyst, alcohol to biomass ratio and reaction time on biodiesel yield were investigated. We also studied a single-step biodiesel production where extraction and transesterification simultaneously take place, and made comparison between this method and the conventional two-step biodiesel production process.