  Based on a collective description of electrolytes composed of
charge-regulated macro-ions and simple salt ions, we analyze their equilibrium
charge state in the bulk and their behavior in the vicinity of an external
electrified surface. The mean-field formulation of mobile macro-ions in an
electrolyte bathing solution is extended to include interactions between
association/dissociation sites. We demonstrate that above a critical
concentration of salt, and similar to the critical micelle concentration, a
non-trivial distribution of charge states sets in. Such a charge state can
eventually lead to a liquid-liquid phase separation based on charge regulation.
