Adsorption behaviour of trifluoromethane-sulfonate ions at the mercury/electrolyte interface from single salt solutions

Abstract

A comparison is made of the adsorption behaviour of CF 3SO − 3 ions on mercury from single salt and constant ionic strength solutions. For this purpose, thermodynamic analysis was made of the experimental results of measurements of capacitance, potentials of zero charge and surface tensions from single salt solutions in this work, and from constant ionic strength solutions, as reported in an earlier communication. The extent of adsorption from single salt and constant ionic strength solutions is small; however, the adsorption is larger from single salt than from constant ionic strength solutions. The maxima in plots of specifically adsorbed charge versus electrode charge, interpreted due to competition with water molecules, are observed only in constant ionic strength but not in single salt solutions. The structure of the interface and the adsorption isotherm for CF 3SO − 3 ions are analysed in terms of an electrostatic model of the double layer.