, Volume 88, Issue 1, pp 91-99
Date: 19 Aug 2010

Simplifying the Process of Microalgal Biodiesel Production Through In Situ Transesterification Technology

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Abstract

Crop-based biofuels, including biodiesel, has sparked international concerns during recent years. Microalgae have been strongly advocated as the most promising substitute for oil crops. However, the commercialization of microalgal biodiesel is hindered by the high costs of feedstock and conventional production processes. This paper elucidates a simplified, scalable production process under conditions of least energetic demand, which integrates oil extraction and conversion into one step through in situ transesterification. Introducing a co-solvent is the key to success. Criteria for co-solvents applicable to the microalgal biodiesel industry are proposed. The overall biodiesel yield (OBY) of Spirulina was determined for benchmarking purposes, using the Bligh and Dyer protocol for oil extraction, and transesterification with potassium hydroxide. The performance in in situ transesterification of the selected co-solvents toluene, dichloromethane and diethyl ether, as well as the solvent combinations petroleum ether/toluene, toluene/methanol and dichloromethane/methanol, was evaluated by OBY. Among all the co-solvents tested, the toluene/methanol system, 2:1 by volume ratio, demonstrated the highest efficiency, achieving a biodiesel yield of 76% of the OBY for the first in situ transesterification cycle and 10% for the second in situ transesterification cycle.