Levulinic acid-based deep eutectic solvent and n-heptane for efficient oil extraction process from rubber seed

Abstract

Deep eutectic solvents (DESs) have attracted significant interest in chemical separation, particularly in the field of extraction processes. This study investigated the process of sono-energy-assisted oil extraction from rubber seeds using DESs as co-solvents in the presence of n-heptane and diethyl ether. Three DESs co-solvents were prepared from choline chloride (ChCl) as the hydrogen bond acceptor and glycerol (Gly), levulinic (LevA), and diethylene glycol (DEG) as the hydrogen bond donors. The kinetics and optimization of the operating parameters, including temperature, the mass ratio of seeds to organic solvent to DES, as well as extraction time, were examined. The highest yield of oil of 31.3 % was achieved using ChCl:LevA(1:2) and n-heptane at a temperature of 50°C, and a contact time of 60 min. The extraction temperature can be reduced using ChCl:LevA(1:2) in the presence of n-heptane compared to pure n-heptane, while the oil yield was enhanced by 3.3 %. Furthermore, a conductor-like screening model for a real solvent (COSMO-RS) was employed to elucidate the extraction mechanism where DESs could facilitate the disruption of the protective protein membranes surrounding the oil droplets. This is the first study for application of ChCl:LevA(1:2) as natural co-solvent for oil from rubber seeds and this co-solvent can contribute in energy saving required for oil extraction.