Wirote Yourvaong, Alistair Steven Grandison and Michael John Lewis

pp. 929 - 939

Abstract

The effects of physical and physicochemical changes by modifying pH, increasing ionic strength and
adding CaCl₂
 or citrate of skimmed milk on the critical flux and fouling reversibility during ultrafiltration
were studied. The critical flux of skimmed milk was decreased as skimmed milk was modified by these
methods. In general, decreases in critical flux were explained well by the surface charge of the particles
such as whey proteins, casein micelles, and particle size distribution. The critical flux appeared to decrease
as the surface charge of these proteins decreased. The results also indicated that small particles e.g. whey
proteins and casein molecules played a major role in determination of critical flux. The fouling reversibility
appeared to be dependent on physicochemical properties of skimmed milk. Fouling reversibility decreased
(irreversible fouling increased) when lowering the pH, increasing ionic strength and adding CaCl₂
 and
increased when increasing pH and adding citrate.

Keywords

• critical flux
• ultrafiltration
• particle size
• fouling