ANALYSIS OF COADSORPTION DATA FOR TETRAMETHYLAMMONIUM AND TETRABUTYLAMMONIUM IONS AT THE MERCURY WATER AND MERCURY DIMETHYL-SULFOXIDE INTERFACE

Experimental data for the coadsorption of tetramethylammonium (TMA+) a nd tetrabutylammonium (TBA+) ions at the Hg/H2O and Hg/dimethyl sulfox ide (DMSO) interface were analyzed in terms of an electrostatic model distinguishing a region of the diffuse layer inaccessible to part of t he ions where the dielectric constant, epsilon1, is lower than the bul k solution value (epsilon). Under the condition that the value of epsi lon1 is a function of charge of the Hg electrode, this model is able t o describe the displacement of TBA+ ions by TMA+ ions at high negative charge densities.