Effects of proteins on electrokinetic properties of inorganic membranes during ultra- and micro-filtration

The streaming potential is measured across inorganic ultra-filtration and micro-filtration membranes to characterize them. Concurrently, electrophoretic mobility measurements are carried out to study the membrane material. The influence of whey proteins on the streaming potential and electrophoretic mobility is also studied. Results show that the membrane interface after adsorption has a surface property behavior similar to that of the proteins from a charge point of view. Moreover, the streaming potential considers two aspects of filtration which must take into account the steric and electric effects. In an electrolyte solution without proteins, the streaming potential depends only on charge repartition, determined by pH value. With whey proteins, the streaming potential depends on both charge repartition and permeate flux. If there is no inner fouling, the charge repartition is not affected and the streaming potential depends exclusively on flux; when there is an inner fouling by protein adsorption, the pore surface is modified and the streaming potential depends on both permeate flux and on electric charge of the oxide-solution interface.