Differential permeation of oil constituents in nonporous denser polymeric membranes

Edible oil processing has become one of the prime targets for membrane appl ications. In the present study, attempts were made for the first time to ex amine the applicability of the transport equations for oil systems. Permeab ility of the constituents of the homogeneous mixtures and rejections of ind ividual constituents were studied, Oleic acid permeated preferentially when compared with triglycerides. The total permeate flux increased from 90.6 t o 151g/(m(2) h) when the oleic acid content in the feed was increased from 1.9 to 21.2%, which is mainly due to the increase in the permeation rate of oleic acid. The synergistic effect of preferential sorption and concentrat ion dependent solubility as well as diffusivity could be responsible for th e higher relative permeability of oleic acid. In the present case of proces sing liquid mixtures (oleic acid and triglycerides) by nonporous denser mem branes, the contribution of solution-diffusion to transport is more than us ually observed in reverse osmosis (RO) membranes. Higher operating temperat ure and pressure increased the total permeate flux. Relative permeation rat e of oleic acid increased with pressure. In case of phosphatidylcholine (PC ) and triglycerides (solute-solvent) system, the rejection of PC was above 98% and it did not vary significantly either with feed concentration or wit h operating conditions. The membrane rejected chlorophyll almost completely . (C) 2001 Elsevier Science B.V. All rights reserved.