A Study on Gold(III) Recovery Via Foam Separation with Nonionic Surfactant in Batch Mode

Foam separation of Au(III) from its hydrochloric acid solutions was studied in a batch mode using a nonionic surfactant: polyoxyethylene nonyl phenyl ether having 20 ethylene oxide units (PONPE20). The surfactant showed a strong affinity to Au(III) in HCl media and played a double role of foam-producer and metal-collector. Effects of experimental parameters, such as the length of drainage section of the column, concentration of the surfactant and the metal, air flow rate and solution temperature, were discussed in terms of the recovery and the enrichment of Au(III). The recovery increased with an increase in the concentration of surfactant and in air flow rate, while the enrichment improved with decreasing air flow rate and increasing the length of drainage section. The behavior of Au(III) adsorption onto the foam was also analyzed in terms of the surface excess, and the Freundlich’s adsorption isotherm was successfully applied to the system. Moreover, the selective separation of Au(III) from several heavy metals and the application of cloud point extraction to the present foamate solution were also carried out with the resultant enrichment ratio of 59