FRACTIONATION OF BSA AND LYSOZYME USING ULTRAFILTRATION - EFFECT OF GAS SPARGING

Fractionation of proteins by ultrafiltration is an interesting challen ge. With a particular membrane, the protein-protein and protein-membra ne interactions largely decide which protein passes through and which is retained. System hydrodynamics also affects protein fractionation a s the transmission behavior of a protein is altered by concentration p olarization. Therefore, disruption of the concentration polarization l ayer would help to maintain the native selectivity of the membrane and hence aid in protein fractionation. An attempt is made to use gas spa rging, a technique proven effective in controlling concentration polar ization to enhance the selectivity of separation of BSA (MW 67,000) an d lysozyme (MW 14,100). The effects of gas flow rate, liquid flow rate and feed concentration on the selectivity of fractionation are examin ed. Gas sparging enhances protein fractionation; under suitable soluti on conditions, nearly complete separation of BSA and lysozyme was achi eved with gas sparged ultrafiltration. The permeate flux was also incr eased by gas sparing. The mechanism of enhancement is explained in ter ms of disruption of the concentration polarization layer and enhanced mass transfer due to bubble-induced secondary flow.