Separation of n-butane from soybean oil mixtures using membrane processes

Separation of refined soybean oil/n-butane mixtures was studied in this work using different commercial ultra- and nanofiltration membranes, with cut-offs ranging from 1 to 5 kDa. Refined soybean oil/n-butane mixtures at 1:3 (w/w) and 1:1 (w/w) mass ratios were continuously fed to a tangential flow module. The effects of the feed pressure (10–25 bar) and the transmembrane pressure difference (1–10 bar) on oil flux and retention were investigated. Oil retention results ranged from 52.8 to 99.1% and n-butane flux up to 2730 g/m2 h were obtained. Membrane fouling was observed in all experimental conditions studied. The membrane separation process has proven to be a promising alternative to the recovery of the pressurized solvent.