Extraction of lipids from post-hydrolysis copra cake with hexane as solvent: Kinetic and equilibrium data

Copra cake (CC), an agro-industrial residue produced in the manufacture of coconut oil, still has a considerable amount of lipids (∼15 %w/w). In order to valorize the residue, CC was subjected to dilute acid hydrolysis to produce a solid residue with higher lipid content of ∼25 %w/w. Considering the substantial amount of lipids available in the post-hydrolysis copra cake (PHCC), it is necessary to gather lipid extraction kinetics and equilibrium data for process and equipment design. The effects of solvent-to-solid ratio (4, 8, and 12 mL/g) and temperature (30, 40, and 50 °C) on the kinetics and equilibrium of lipid extraction from PHCC using n-hexane as solvent was investigated. Regardless of extraction temperature and SSR, equilibrium is reached in less than 10 min. To appropriately describe the lipid extraction system, various kinetic models were fitted, with the Modified-Peleg’s model best representing the extraction process (R2 ≥ 0.95). Extraction of lipids from PHCC required less amount of solvent to extract and recover the same amount of lipids present in CC. The fatty acids in the extracted lipids are primarily lauric acid. Fuel properties based on the fatty acid profile, as estimated using empirical models, were found to be suitable as biodiesel.