Selective adsorption of the gold–cyanide complex from waste rinse water using Dowex 21K XLT resin

The Dowex 21K XLT resin which is a strong basic resin was used to selectively adsorb gold–cyanide complex only, in the actual waste rinse water which coexisted with lead–cyanide complexes. The existence of gold–cyanide complex on the surface of the Dowex 21K XLT resin was proved by SEM and EDX analysis. The maximum removal efficiency value for gold–cyanide complex was about 93% for 10 g/L of resin concentration while adsorption for lead–cyanide complexes did not almost happen at pH 13. The adsorption capacity of Dowex 21K XLT resin for gold and lead–cyanide complexes was about 32 and 0.8 mg/g-dry mass, respectively. Also, most of adsorption process for gold–cyanide complex was completed within 1 h. The exothermic nature of gold–cyanide complex adsorption onto the Dowex 21K XLT resin was revealed because the removal efficiency for gold–cyanide somewhat decreased as temperature increased. It was concluded that the Dowex 21K XLT resin, which has excellent selectivity to gold–cyanide complex, can be applied to the recovery system for gold–cyanide complex in actual waste rinse water.