DSpace JSPUI

The use of externally applied d.c. electric field are investigated for the reduction of concentration polarization and fouling for three industrially relevant systems e.g., clarification of fruit juice, separation and fractionation of protein solution, micellar enhanced dye separation. During clarification of fruit juice, pectin (negatively charged) forms a gel-type layer over the membrane surface leading to a decline in permeate flux. The effects of varying electric field during gel controlled ultrafiltration of synthetic juice (a mixture of pectin and sucrose) and mosambi (Citrus sinensis (L.) Osbeck) juice is investigated. The results demonstrate considerable increase in permeate flux. A theoretical model based on the integral method is developed and numerical solutions are successfully compared with experimental results. The model is used to estimate gel layer concentration, effective diffusivity and effective viscosity of the juice. Pulsed electric field is also used and it is found to be more advantageous. The gel layer thickness is measured with high-resolution video microscopy and successfully compared with results from the numerical solution of a resistance-in-series model. Use of electric field during ultrafiltration of BSA (bovine serum albumin) from aqueous solution has resulted in significant increases in permeate flux. A theoretical model including the effects of external d.c. electric field and suction is developed and solved using similarity solution method and the results are successfully compared with experiments. Electric field enhanced ultrafiltration has been also been carried out for fractionation of aqueous solutions of two proteins e.g., bovine serum albumin (BSA) and lysozyme. A detailed parametric study has investigated the effects electric field, pH, concentration ratio in the feed etc. Removal of dyes from aqueous solution using electric field assisted micellar enhanced ultrafiltration (MEUF) has been studied. Sodium dodecyl sulphate (SDS) and methylene blue (MB) have been taken as anionic surfactant and cationic dye, respectively. The effects of electric field, surfactant to dye concentration ratio, transmembrane pressure and cross flow velocity on permeate flux and retention of MB have been investigated including the development of an expression for limiting flux.