FRACTIONATION OF BSA AND LYSOZYME USING GAS-SPARGED ULTRAFILTRATION IN HOLLOW-FIBER MEMBRANE MODULES

Ultrafiltration experiments were performed on mixtures of BSA and lyso zyme with the aim of fractionating the two proteins. Pilot-plant scale polysulphone hollow fiber membrane modules with molecular weight cuto ffs of 150 000 and 200 000 were used. The membrane process was enhance d via the injection of gas slugs into the hollow fiber membrane module s. The gas slugs served to disrupt concentration polarization near the membrane surface with the subsequent aim of improving membrane select ivity. It was found that hollow fiber membranes were effective at frac tionating BSA and lysozyme, with the membrane selectivity being greate r than 20 across a range of operating conditions. The introduction of gas slugs further improved membrane selectivity by a factor of 3-5. Th e sieving mechanism of the membrane and electrostatic interactions bet ween proteins and the membrane were discussed and used to explain expe rimental observations.