Simulation of supercritical carbon dioxide extraction of lipid from spent coffee grounds

Abstract

Lipids are an inexpensive and high-quality biodiesel raw material. They can be extracted fromspent coffee grounds. The purpose of this study is to obtain the effect of process parameters on the lipid extraction from spent coffee grounds using supercritical carbon dioxide. The hot sphere diffusion model with desorption as the limiting step of releasing solutes to the fluid phase has been used to obtain those parameter effects. The lipid yield increases with increasing pressure at the same temperature, and decreases with increasing temperature at the same pressure. An increase in the extractor height from 0.32 m to 1.5 m gives an increase in the yield from 1.52 grams to 8.32 grams at the same duration of the extraction. When the extractor height is doubled from 1,5 m, the yield reaches 12.28 grams. At the extraction with the particle size of 0.27 mm, the yield produced at 111th minute is 11.83%. The yield decreases to 8.39% when the particle size enlarges to 0.75 mm. The increase in the solvent flowrate from 0.0018 kg/min to 0.005 kg/min, then to 0.01 kg/min causes the lipid yield to increase continuously.