Abstract
The work described in this thesis is based on an investigation into the sorptive behaviour of gold in dilute, aqueous solutions of surface-active agents. Extent of adsorption, by gold, of some long-chain pyridinium bromides, trimethylammonium bromides and sodium sulphates has been measured by the determination of concentration loss from solution. Surfactant concentration has been determined by several methods, of which the "soap antagonistic" titration technique was found to be most useful. Surface area of the gold powder has been determined and used to give a more quantitative picture of the adsorption process. Electrokinetic properties of gold in the surfactant solutions have been investigated by microelectrophoresis-The electrophoretic mobilities determined by this method have been used to calculate electrokinetic potentials and charges for these systems. A simple method of determining flotation has been perfected- The results obtained by this method were consistent with contact angle determinations and proved to be useful in the elucidation of the orientation of surfactant ions at the solid/solution interface. Critical micelle concentration has been determined for each compound studied; these values have been used to calculate reduced concentration. The presentation of results as a function of reduced concentration has enabled direct comparisons to be made between different compounds. Correlations between the different measurements have been interpreted in terms of two-layer adsorption; the possibility of micelle formation in the primary adsorbed layer has also been considered. Some conclusions have been drawn regarding the modes of orientation of surfactant ions in the adsorbed layers.