Biodiesel is a type of renewable, biodegradable, non-toxic, and eco-friendly fuel which has been considered one of the best alternative resources to fossil fuels. Nowadays, one of the most promising substitute sources of biodiesel is considered to be microalgae. It offers several advantages over traditional crops, such as a high lipid content, rapid growth rate, greater photosynthetic efficiency, bio-remediation potential, and versatile growing conditions. This research focuses on the integration of ionic liquids into the process of biodiesel production from microalgae, which holds the promise of overcoming some of the limitations associated with the conventional methods.

This work focuses on the production of biodiesel from Nannochloropsis sp. microalgae. This study compares the effectiveness of conventional methods such as Soxhlet extraction and the Bligh and Dyer method for lipid extraction. The Bligh and Dyer method exhibited a higher lipid yield compared with that from Soxhlet extraction. Sonication parameters (sample volume, time, and power rate) were optimized to maximize the lipid yield. It further investigates the use of ionic liquids for lipid extraction from microalgae. Two ionic liquids, 1-(4 sulphonic acid) butyl-3-Methyl imidazolium hydrogen sulphate and 1-(4 sulphonic acid) butyl pyridinium hydrogen sulphate, were synthesized and characterized using FTIR, NMR, and TGA. As compared to the conventional methods, extraction using ionic liquids showed greater lipid efficiency. Biodiesel was produced through the transesterification of algal oil. FTIR was used to analyze the presence of lipids and esters in biodiesel. The produced biodiesel, with significant properties, meets the terms of the ASTM specifications (pH, density, acid value, free fatty acid, iodine value, and calorific value), indicating its suitability as biofuel.