Interaction of Silver Ions in Solution with Copper Hexacyanoferrate (II) Cu 2Fe(CN) 6

Abstract

The sorption of silver ions from 0.1 MHNO 3solutions on copper hexacyanoferrate (II) Cu II 2Fe II(CN) 6was investigated using batch experiments. Sorption kinetics and isotherms were studied in which ICP/AES was used for determining the amount of sorbed Ag and the quantities of elements released into the solution. Cyclic voltammetry and X-ray diffraction were used for determining the evolution of the solid. This hexacyanoferrate is very efficient for the removal of silver from aqueous solutions: more than 99.999% of the silver can be removed for initial concentrations less than 0.01 mol/l. Silver sorption proceeds with fast kinetics in a first step and with a further slow evolution. The sorption capacity reaches 1.4 g Ag per g of sorbent. The sorption mechanism is rather complex: there is a destruction of the initial crystalline structure along with the formation of new solid phases, among which silver cyanide is predominant.