ULTRAFILTRATION OF HIGH-VISCOSITY SOLUTIONS - THEORETICAL DEVELOPMENTS AND EXPERIMENTAL FINDINGS

The theory of the existence of limiting fluxes and concentrations in t he ultrafiltration of macromolecules is reviewed and extended to non-N ewtonian power-law fluids. Recent work by Pritchard el al. (1995, J. M embrane Sci. 102, 223-235) has shown the existence of situations where the ultrafiltration flux can increase with concentration. The criteri on for this occurring has been developed and evaluated using rheologic al data as a Function of concentration for a variety of fluids includi ng xanthan gum, dextran, pectin and reconstituted whey. These were the n concentrated to high concentrations by ultrafiltration to verify the validity of the criterion. Higher fluxes with increased concentration were only found for xanthan gum.