Biodiesel production from microalgae through solvent mediated simultaneous lipid extraction and conversion

Abstract

Microalgae have become an important source of biodiesel due to their high lipid productivity. Downstream processes for biodiesel production include extraction and transesterification. Because extracting lipids from wet microalgae does not presently provide desirable results, the extraction step needs an additional drying process which is quite energy-intensive. Thus, developing an efficient process for lipid extraction from wet microalgae is a major issue for industrial applications. This work presents a reliable and compact process which integrates lipid extraction from wet microalgae Nannochloropsis oceanica, and its conversion to biodiesel, with a yield higher than 90 wt.%. This process enables single-step production of biodiesel from microalgae by mixing wet microalgal cells with a solvent (e.g., chloroform, toluene, or hexane), methanol and an acid catalyst; and then heating them in one pot. The effects of reaction parameters such as reaction temperature, wet cell weight, reaction time, and catalyst volume on the conversion yield are investigated. By same process, secondary co-product was successfully produced in addition to biodiesel with Nannochloropsis gadatana. This simultaneous extraction and transesterification of wet microalgae enables a dramatic reduction in energy consumption for the drying process and enables the economic production of biodiesel using microalgae.