Interaction between charged colloids in a low dielectric constant solvent

Based on computer simulations of the primitive model of electrolytes, we show that the effective interaction between low-charge colloids in solvents of low or moderate dielectric constant depends crucially on the salt concentration. While in the absence of salt the interaction is repulsive in agreement with Derjaguin-Landau-Verwey-Overbeek theory, depletion of salt Bjerrum pairs around the colloids leads to an attraction between like-charge colloids even at small salt concentrations.