Water compatible resin for separation and recovery of dissolved precious metals

Abstract

The value of precious metals such as gold to be recovered in the industrial effluents within Pearl River Delta area is over HK$20 million per annual. Furthermore, with the expected tightening of environmental legislation and enforcement in the Mainland China, there is a growing need of effluent treatment technology. Traditionally, ion-exchange resin, polymer ultra-filtration and micro-emulsion are applied in the treatment of plating effluents. However, they all have different weaknesses. Many reports have been published for the separation using aqueous biphasic system. Based on this methodology, polystyrene-grafted-polyglycidol (PS-PG), a water-compatible polymer was synthesized. This type of polymer can be used for gold or silver extraction. After extraction, the recovery of metal can be achieved by direct electro-deposition or reverse extraction using sodium cyanide.