A power-law model of electrostatic interactions of colloidal particles in cake layer on membrane surface

The permeability of cake on membrane surface is a crucial factor affecting the efficiency of low pressure membrane process. In this study, a power-law model was suggested for better understanding of the effect of solution chemistry on cake permeability. The model equation was derived from the classical Derjaguin–Landau–Verwey–Overbeek (DLVO) theory and the dimensional analysis of parameters affecting the chemical interactions of colloidal particles. Experimental results from unstirred filtration of submicron latex particles at various ionic strengths were used for model application. The permeate flux as well as specific cake resistance and cake porosity was sensitive to ionic strengths. Different behaviors of cake permeability were observed for non-aggregated and aggregated particles. The proposed model aids to interpret complicated relations of cake permeability in terms of the characteristic ratio, which is defined as the ratio of electrostatic repulsion to van der Waals attraction.