The effect of large particles on microfiltration of small particles

The effects of the presence of large latex (1 mum) particles on the microfi ltration of small gold (50 nm) colloidal suspensions have been investigated using hydrophobic 0.22 mum polyvinylidene fluoride (GVHP) micro-filtration (MF) membranes. Gold sol was filtered through the membrane with or without prefiltration of latex suspension. The characteristics of the cake formed on the membrane surface depends not only on the intrinsic properties of the particles in the feed but also depends on the nature of the mixture. The t ype of cake formation (e.g. a cake of small particles on the top of large p articles or a cake of mixed particles) affects the cake properties due to t he combination effect. This can be explained by the type of filling of the voidage between large particles with small particles. Various combinations of these particles result in cakes with different resistances. The understa nding of the combination effect and the type of cake formation has a potent ial application for fouling minimization. Fouling is surprisingly serious i n microfiltration of the feeds containing mixed particles. Separation of la rge particles prior to the microfiltration of suspension of small particles can reduce cake resistance and minimize fouling.