Selective Separation of Fine Particles at a Charged Solid/Liquid Interface

This paper considers recent developments in theoretical models which may be used to simulate particle capture processes and the feasibility of separating colloidal species according to their surface charge, by selective and reversible adsorption onto a collector surface. Selectivity is achieved through control of the electrochemical potential of the collector. The principles of controlled-collector-potential chromatographic separation (CCPCS) methods are illustrated for the separation of alumina and titania particles (200 nm radius) at a macroscopic platinum (oxide) collector in aqueous electrolytes for a flow-through sandwich-cell separation module. For this ceramic system separation via the secondary minimum interaction energy level is not possible, however, selective separation based on differences in the DLVO energy barrier using potential control seems feasible. Practical limitations on the selection of appropriate approximations to describe particle-collector interaction and the role of heterogeneities in particle/charge properties are discussed.