Adsorption from aqueous solutions of ionic surface-active agents by gold. Part 1

Abstract

Measurements have been made of the extent of adsorption from aqueous solutions by gold of some long-chain pyridinium bromides and sodium sulphates. Electrokinetic properties of gold in these solutions have also been investigated by microelectrophoresis. The degree of adsorption of the cationic surface-active agents was greater than that of the anionic compounds and a congruent function of reduced concentration within a homologous series of compounds. The isotherms exhibit a two-step character which, from the electrophoretic data, may be interpreted in terms of a two-layer adsorption mechanism. Specific adsorption of surfactant anions in the primary layer is postulated and it is suggested that the electrophoretic data allow conclusions to be drawn regarding the modes of orientation of surfactant ions in the adsorbed layers.