ADSORPTION OF PYRIMIDINE AT THE MERCURY AQUEOUS-SOLUTION INTERFACE

The adsorption of pyrimidine on a mercury electrode from 1 M KF soluti ons is studied by means of differential capacity, zero charge potentia l and maximum surface tension measurements. The data are analysed conf orming to the Frumkin isotherm and to the Nikitas approach. A value fo r the size ratio parameter close to one is obtained. The interaction p arameters depend on the electrical variable and indicate predominant a dsorbate-solvent interactions at the potential of maximum adsorption. The maximum standard Gibbs energy of adsorption is indicative of physi cal rather than chemical adsorption. The comparison with other diazine s, pyrazine and pyridazine, and with pyridine on the basis of the Esin -Markov effect and the electrosorption valency at low coverages allows some conclusions to be drawn about the relative roles played by the e lectrostatic interactions with the field and the electronic interactio ns with the metal, and the participation of H-bonds with the solvent.