Interaction of silver ions in solution with copper hexacyanoferrate (II) Cu2Fe(CN)(6)

The sorption of silver ions from 0.1 M HNO3 solutions on copper hexacyanoferrate (II) (Cu2FeII)-Fe-II(CN)(6) was 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. (C) 1997 Academic Press.