Effect of electric field during gel-layer controlled ultrafiltration of synthetic and fruit juice

Electric field enhanced ultrafiltration of pectin-sucrose mixture (synthetic juice) and mosambi (Citrus sinensis (L.) Osbeck) fruit juice using 50 000 (MWCO) polyerthersulfon membrane is studied in a cross-flow cell. Pectin, completely rejected by the membrane, forms a gel type layer over the membrane surface. Under the application of an external dc electric field across the membrane, gel-layer formation is restricted leading to an enhancement of permeate flux. During ultrafiltration of synthetic juice, application of dc electric field (800 V/m) increases the permeate flux to almost threefold compared to that with zero electric field. A theoretical model based on integral method assuming suitable concentration profile in the boundary layer is developed. The proposed model is used to predict the permeate flux in gel-layer governed electric field enhanced ultrafiltration. Predictions of the model are successfully compared with the experimental results under a wide range of operating conditions. Experiments with fruit juice also demonstrated significant increase in flux with the application of a suitable electric field. (C) 2007 Elsevier B.V.. All rights reserved.