ADSORPTION OF METAL IONS ON STEARIC ACID-NONADECANE PARTICLES IN AQUEOUS SOLUTIONS

The adsoption of metal ions at the stearic acid/electrolyte and nnonadecane-stearic acid mixture/electrolyte interface was investigated by means of the potentiometric titration, zeta potential and adsorption measurements. It was found that the studied colloidal suspensions exhibited an adsorption affinity towards multivalent metal ions. The adsorption of Ca^2, Cd^2 and Al^3 ions caused a strong decrease of surface charge density and zeta potential values in this systems. The adsorption reactions occur by way of cation exchange with protons from two surface carboxyl groups. At high metal concentrations, in adsorption reactions there are involved also carboxyl groups from the subsurface layer. On the basis of the adsorption data, the cation surface complexation constants were calculated by Shindlerʹs method.