Soybean oil extraction with ethanol from multiple-batch assays to reproduce a continuous, countercurrent, and multistage equipment

Abstract

The replacement of toxic organic solvents from fossil sources by nontoxic ones from biorenewable origin in large-scale processes has been a frequent search. Although ethanol has been currently investigated as a hexane-substitute for vegetable oils extraction, most studies are conducted on laboratorial scale and in batch assays. Initial parameters of a continuous and countercurrent extractor that indicates the technical possibility of a large-scale operation are still scarce. Here, a continuous extractor composed of fixed bed columns connected in series (resembling the so-called simulated moving bed extractor) for soybean oil extraction with anhydrous ethanol was experimentally reproduced by a multiple-batch solid-liquid extraction system. After a 5-stage extraction, the residual oil in the solid phase was 0.17% with 99.2% extraction yield, confirming that ethanol was capable to exhaust the solid matrix with a reasonable extraction yield. Although the minimum solvent-to-feed ratio (S/F) for ethanol (S/F = 2.62/1) was higher than that for hexane (S/F = 0.36/1), benefits in relation to food safety, reduction in handling danger, and less environmental impact reinforce ethanol as a safe and promising solvent for the extraction of vegetable oils in a continuous equipment.