Investigation of Pulsed Electric Field (PEF) as an Intensification Pretreatment for Solvent Lipid Extraction from Microalgae, utilizing Ethyl Acetate as a Greener Substitute to Chloroform-based Extraction

Abstract

As a crucial alternative to petroleum liquid fuels and first generation biodiesel, microalgae represent the most promising renewable source of lipids, thought to be capable of meeting global transportation fuel needs. The most promising characteristics of this alternative energy source are its CO2 neutrality, high biomass growth, high lipid yield, and noncompetitive stance toward food supply. To date, development of economically feasible lipid solvent extraction processes of industrial scale face two significant challenges: green solvent selection with efficient extractive characteristics and requirement of cell disruption pretreatment. In this contribution, the utilization of ethyl acetate-based solvents is suggested as a green alternative. Moreover, the novel utilization of Pulsed Electric Field (PEF) as a membrane permeating technique for intensification of the lipid extraction is analyzed. When compared to inherently toxic chloroform-based solvent (Bligh & Dyer method), this work characterizes ethyl acetate as a less efficient and slower solvent in extracting lipids from Ankistrodesmus falcatus wet biomass. A possible explanation to these inefficiencies was hypothesized to be ethyl acetate's poor membrane disintegration capabilities. In regards to lipid extraction intensification, the utilization of PEF as a membrane disrupting pretreatment was investigated, focusing in the inefficiencies presented by the ethyl acetate-based system. The novel application of PEF to Ankistrodesmus falcatus wet biomass suspension resulted in mixed conclusions. Although no increase in total lipid extraction was achieved, a significant enhancement in the rate of lipid recovery was demonstrated. This crucial intensification shows the PEF application is a valid enhancement treatment that warrants further investigation.