Selective separation of silver from waste solutions on chromium(III) hexacyanoferrate(III) ion exchanger

Abstract

The inorganic ion exchanger chromium(III) hexacyanoferrate(III) has been found to be specifically selective for silver ions, with a sorption capacity of ca. 10 mequiv. g^–1 of the exchanger. Sorption of the silver ions from acidic (10 mol dm^–3 HNO₃) and salt solutions (8 mol dm^–3 NH₄NO₃), containing different levels of silver nitrate, has been studied. The studies, which were aimed at using the exchanger for the recovery of silver ions from the waste, generated from chemical oxygen demand determinations, showed ca. 80–95% recovery of silver ions from concentrated waste. The exchanger also selectively removed silver ions from simulated waste containing Bi, Ca, Cd, Co, Cu^II, Mg, Mn, Ni, Pb and Zn ions.