PULSED-ELECTRIC-FIELD CROSS-FLOW ULTRAFILTRATION OF BOVINE SERUM-ALBUMIN

A conventional crossflow ultrafiltration (CUF) apparatus was modified by the inclusion of electrodes which permitted a pulsed electric field to be produced across the ultrafiltration membrane (PEF-UF process). Using this apparatus, a discontinuous electrophoretic velocity was imp osed upon the proteins being concentrated, opposing their convective m ovement toward the CUF membrane. This resulted in a lower concentratio n of rejected solute protein in the fluid boundary layer adjacent to t he high-pressure side of the membrane and, hence, in a lower solute-re lated filtration resistance than in the case of conventional ultrafilt ration (zero electric field). Studies of the PEF-UF process with bovin e serum albumin (BSA) in the range of 0.5-5% w/v demonstrated a 25-40% decrease in the solute-related resistance to the permeate flux compar ed to the case of a zero electric field. Accordingly, higher permeate fluxes and, therefore, higher rates of concentration of the protein so lution were obtained than for conventional crossflow ultrafiltration. When the electric field was reimposed following a period of operation under conventional CUF conditions, the permeate flux could be restored to nearly the same higher value observed initially for the PEF-UF pro cess.