Separation of platinum, palladium and rhodium from aqueous solutions using ion exchange resin: A review

Demand for platinum (Pt), palladium (Pd) and rhodium (Rh) as parts of platinum group metals (PGMs) has continued to increase as a consequence of increase in their applications. Various extraction methods have been developed to produce the metals including leaching-based process using halides, sulfate-chloride and cyanide, which generate leach liquors containing metal ions together with impurities. Separation processes are essentially employed to obtain metals of high purity for further applications. Among the widely applied techniques, ion exchange with the use of resins becomes one of the most important approaches. This paper reviews the separation of Pt, Pd and Rh by ion exchange resins from various solutions while considering the presence of other metals such as other PGMs, Au, Ag and base metals. The basic solution chemistry, type, properties and preparation of ion exchange resins including industrial and proposed flow sheets are also presented. In addition, an outlook for the further work in this area is provided.