Sustainable extraction of rice bran Oil: Assessing renewable solvents, kinetics, and thermodynamics

Abstract

Rice bran (RB) oil extraction was performed by applying renewable solvents like ethanol and ethyl acetate. To assess the interaction of these solvents with the oil, the UNIFAC model was chosen to determine the infinite dilution activity coefficient. Soxhlet extraction was utilized to determine the maximum possible yield. The adequacy of the experimental data to mass transfer kinetic and thermodynamic models was investigated with response surface methodology. By the theoretical adjustment, statistical parameters (R²adj of 0.9398 for ethanol and 0.8525 for ethyl acetate) showed that the temperature and solvent/RB ratio have a notable influence on oil extraction. The experimental data agreed with the kinetic model based on solid-liquid mass transfer. The thermodynamic study showed that both solvents have endothermic, spontaneous, and irreversible processes. Interestingly, ethyl acetate had higher extraction yields at the beginning and reached its highest yield in a shorter time interval due to better compatibility with oily compounds present in rice bran and its lower viscosity.