The Advancement of Selectivity in FFAs and TAGs

Algae biofuels are being explored as a potential renewable fuel source due to their cost-effectiveness and environmental advantages. Certain algae species can produce triglycerides (TAGs) under nutrient-limited growth conditions. In biofuel production, TAGs are the primary form of lipids that can be converted into biodiesel through transesterification into fatty acid methyl esters (FAMEs). During the cultivation and extraction of lipids from algae for biofuel production, certain conditions, including acidic, basic, thermal, and oxidative environments, can lead to the breakdown of TAGs into free fatty acids (FFAs), which are not ideal for biofuel production. Understanding and controlling these factors is important for optimizing algae biofuel production during the harvesting and processing steps. This research aimed to investigate the transesterification of TAGs and esterification of FFAs into FAMEs, with a focus on developing a method to selectively convert FFAs over TAGs. FAME production from TAG and FFA standards was achieved using different acid-catalyzed reaction conditions by varying the sulfuric acid content (in methanol), the reaction temperature, and the reaction time. Gas chromatography-mass spectrometry (GCMS) was used to identify and quantify the TAGs and FFAs converted to FAMEs. FFAs were rapidly converted to FAMEs during all reaction conditions tested, followed by unsaturated TAGs and then saturated TAGs. To further support the quantification of FFAs conversion, acid/base titrations were conducted. For future experiments aimed at improving FFA selectivity, alternative catalyst options, such as phosphoric acid or hydrochloric acid, and the use of ethanol or isopropanol as solvents will be explored.