Biodiesel production from wet marine microalgae via a one-step direct process in the presence of an adsorbent

To decrease the cost of biodiesel production from microalgae, biodiesel was produced from wet marine microalgae by a one-step direct process. In this process, simultaneous lipid extraction from the wet microalgae and transesterification of the lipid with methanol was conducted. Among the combinations of catalysts and organic extraction solvents that were evaluated, sulfuric acid and chloroform represented the optimum combination. The degree of water content for wet microalgae significantly influenced biodiesel production: in the presence of 348.4% water content in intact wet microalgae, lipid extraction efficiency (LEE) was 73.2% and biodiesel conversion (BC) was 50.5%, but at a lower water content of 185.7%, LEE increased to 84.7% and BC to 69.9%. Increasing the amount of chloroform by 50% relative to the standard amount increased LEE and BC to 81.2 and 56.1%, respectively. Of the adsorbents evaluated, zeolite noticeably increased LEE to 98.7%. Increasing the amount of chloroform by 50% in the presence of zeolite caused a further significant increase in LEE and BC to 98.3 and 75.3%, respectively. These results indicated that biodiesel production from wet microalgae could be enhanced markedly by the addition of adsorbents with increased amounts of organic extraction solvents.