ULTRAFILTRATION OF NON-NEWTONIAN FLUIDS

The current study reports on a series of ultrafiltration experiments u sing newtonian and non-newtonian fluids (pectine, xanthan and polyacry lamide solutions). For non-newtonian pseudoplastic fluids, the shape o f the plot of flux versus log(bulk concentration) is different to the linear decline in flux which would occur throughout. Moreover, we obse rved that the axial velocity exponent decreases with increasing bulk c oncentration. An empirical equation for the laminar mass transfer coef ficient of a pseudoplastic fluid has been proposed which includes a Si eder and Tate type correction factor. The equation is a tool for under standing the decrease in axial velocity exponent with increasing bulk concentration. However, a comprehensive numerical model is necessary t o get better agreement between observed and predicted axial velocity e xponent and permeate flux.