Adsorption isotherms are calculated for precipitate and floc foam flotation within the framework of a Gouy-Chapman model which includes both the electrical attractions of the floc particles to the surface and their electrical repulsions for each other. The canonical ensemble is used, and algebraic expressions are found for approximating the sum of products of cluster integrals. Algebraic expressions for the surface excess of adsorbed floc are obtained which involve three reasonably simple integrals. The dependence of the adsorption isotherms on temperature, ionic strength, surface potentials of the floc and the air-water interface, ionic charge, and floc particle size is investigated.