THE SEPARATION OF Au(III) AND Pd(II) IN HYDROCHLORIC ACID SOLUTIONS BY STRONG ANION TYPE II EXCHANGE RESINS: THE EFFECT OF COUNTER ION CONCENTRATION AND TEMPERATURE

The separation of gold and palladium ions in hydrochloric acid solutions by strong anion Type II exchange resins is studied in batch and column operations. Increases in the hydrochloric acid concentration and the temperature of the adsorption process have the effect of decreasing the adsorption capacity and the separation factor of both metals. A faster kinetics of the adsorption process of both ions results from temperature increase and this effect is higher for gold ions as a result of greater changes in its diffusivity. Although the adsorption capacity of palladium ions is lower at equilibrium conditions, the adsorption isotherms obtained suggest that they are more strongly retained by the polymers. The high capacities of these resins for both metals permits their use in the preconcentration of gold and palladium but their application in quantitative separation is restricted by the co-elution of up to% of the interfering ion during the desorption process. The best method for ion desorption is sequential elution with% ammonia for palladium recovery followed by 0·5M thiourea in HCI 1M for the recovery of gold.