Improved transport of gold(I) from aurocyanide solution using a green ionic liquid-based polymer inclusion membrane with in-situ electrodeposition

Abstract

Ionic liquid-based polymer inclusion membranes (PIMs) are an environmentally benign separation technology. PIMs are especially suitable for separation of dilute substances, but their application is hindered by their relatively low permeability rate. In this paper, a novel ionic liquid-based PIM system integrated with an electroplating unit was developed to improve the permeability of gold from aurocyanide solutions. Under the optimal conditions, 98.6% of gold(I) was transported, and more than 96.4% of gold was simultaneously deposited on the copper cathode. The gold(I) transport rate was considerably enhanced with in-situ electrodeposition of gold in the stripping phase. With a constant voltage of 1.50V applied to the stripping solution, the permeability coefficient increased from 9.25×10−6m/s (with no voltage) to 21.5×10−6m/s (with voltage). SEM and EDX analysis show metallic state gold was coated evenly on the surface of the electrode. Results of a stability evaluation experiment show that the PIM can be operated stably for 10 cycles on a continuous run mode. The method of simultaneous transport and in-situ electrodeposition expands the application of the PIM technology for separation, which shows good prospects for the removal and recovery metal ions.