 Electric double layer

An electric double layer consists of an interfacial electric charge and the compensating distribution of mobile ions in the adjacent chemical solution. Counterions are enriched and coions depleted near a simple charged interface. A diffuse layer is described approximately by the Poisson-Boltzmann equation; a compact specifically adsorbed layer requires additional surface chemistry. Overlap of diffuse layers can produce a screened repulsion between like-charged colloids.