Effect of ionic surfactants on the electrophoretic mobility of hydroxyapatite

Electrophoretic mobility measurements have been used to determine the point of zero charge and the effect of several different anionic and cationic surfactants on the interfacial properties of hydroxyapatite. All surfactants behave as indifferent electrolytes at very low concentrations. At higher concentrations, oleate and sulfonate ions are specifically adsorbed whereas tridecanoate ions precipitate as a calcium salt. Only dodecylammonium chloride exhibits hemimicelle formation. Physicochemical mechanisms are postulated to explain the electrical double layer at hydroxyapatite/surfactant solution interface.