EFFECT OF ETHANOL ON ULTRAFILTRATION OF BOVINE ALBUMIN SOLUTIONS WITHORGANIC MEMBRANES

This paper investigates the ultrafiltration of albumin-ethanol solutio ns on polysulfone hollow fiber membranes with 30 kDa cut-off. The aim is to identify the mechanisms responsible for the observed permeate fl ux reduction in presence of ethanol. The variations of permeate flux w ith transmembrane pressure and wall shear rate fit the usual pattern o f flux limitation by concentration polarization. Thus, although ethano l significantly increases the permeate viscosity, the data show that t he flux decrease is not a direct consequence of the viscosity increase but rather due to reduced albumin diffusivity which decreases the bac k transport to the bulk solution. The specific resistance of the album in layer on the membrane was found to be unaffected by the presence of ethanol. However the fouling potential of our solutions was found to be significantly increased by the addition of ethanol. Thus the observ ed flux reduction due to ethanol seems to be explained by a combinatio n of a thicker polarization layer caused by reduced back transport and increased membrane fouling. A 10% increase in filtrated volume can be obtained by imposing periodic retrofiltrations which decrease fouling .