CONCENTRATION PROFILES OF A COLLOIDAL MIXTURE NEAR A CHARGED WALL

The structure of a model two-component colloidal mixture in the vicinity of a charged wall is studied in the framework of the Derjaguin-Landau-Verweg-Overbeek potential and the hypernetted-chain approximation for the particle-particle and wall-particle direct correlation functions as the closure for the bulk and wall-particle Ornstein-Zernike equations. It is found that for strongly repulsive walls the structure of the inhomogeneous mixture near the wall only depends on the bulk parameters. For neutral and attractive walls, a monolayer of colloidal particles adjacent to the wall is formed. Depending on the charge asymmetry between the two colloidal species, the composition of this monolayer indicates a preferential electrostatic adsorption of the more highly charged species. For large charge asymmetry between the two species, a distinct segregation effect is predicted.