Separation of soybean oil/n-hexane and soybean oil/n-butane mixtures using ceramic membranes

•The rejections and the oil permeate fluxes were influenced by the feed concentration.•The system oil/n-butane presented higher oil rejection compared to the oil/n-hexane.•The results indicated potential applicability of the technology in the oil industry.

This study aimed to investigate the separations of mixtures of refined soybean oil/n-hexane, crude soybean oil/n-hexane (industrial miscella) and refined soybean oil/pressurized n-butane using membrane technology. Commercial ceramic membranes with molecular weight cut-offs between 5 and 10 kDa were employed, varying the mass ratios of the oil/solvent, from 1:1 to 1:3 (w/w). Oil rejections up to 100%, total permeate fluxes (oil + solvent) up to 42.97 kg/m2 h with oil permeate fluxes up to 1.4 kg/m2 h were obtained. The industrial miscella showed the same behavior observed for the synthetic mixtures presenting an increase in the oil rejection with a decrease in total permeate flux. In the separation of the oil/n-butane mixtures, higher oil rejections were obtained when compared to the system oil/n-hexane. The results presented in this work indicate the potential applicability of membrane technology in vegetable oil processing and biodiesel industries in the solvent recovery step.