The interaction of two spherical colloidal particles in electrolyte solution. An application of the hypernetted-chain approximation

Abstract

The hypernetted-chain approximation is solved numerically for a pair of identical spherical colloidal particles immersed in an electrolyte solution. We consider a simple model system where the ions are hard spheres with embedded point charges and the colloidal particles are much larger hard spheres bearing a uniform surface charge distribution. The surface charge density is considered to be constant independent of the particle separation. We obtain the potential of mean force acting between the colloid particles and the structure of the double layer about a single particle. It is found that under some conditions the colloid-colloid interaction is attractive at small separations even in the absence of van der Waals forces. This result should be of interest in the theory of colloidal stability.