Biodiesel fuel production from algal lipids using supercritical methyl acetate (glycerin-free) technology

Supercritical methyl acetate (SCMA) technology was demonstrated for converting total lipids from Nannochloropsis salina into fatty acid methyl esters (FAMEs) and triacetin (TA). In this non-catalytic process, triacetin is produced instead of glycerin as a side-product during transesterification which is miscible with FAME and can be readily used as biodiesel fuel (BDF). Supercritical carbon-dioxide (SC-CO₂)_,clean and green technology was employed to extract total lipids from algal biomass. The process parameters such as lipid to methyl acetate molar ratio, reaction temperature and reaction time were studied to evaluate their effects on the FAME yield and algal biodiesel fuel yield. Algal lipid characterization and algal biodiesel fuel analysis were carried out using analytical instruments such as FTIR and GC–MS. Thermogravimetric analysis under nitrogen and oxygen environments was performed to examine the thermal and oxidative stability of the algal biodiesel fuel. A micro-elemental analysis (CHNOS) of total algal lipid and biodiesel fuel was performed according to ASTM methods. The fuel properties of algal biodiesel fuel produced were compared with those of the regular diesel and biodiesel American Society for Testing and Materials (ASTM) standards.