Ion exchange performances of electroactive nickel hexacyanoferrate thin films in aqueous solutions containing Pb~(2+)

Electroactive nickel hexacyanoferrate(NiHCF) thin films were synthesized by cathodic deposition.The performance of electrochemically switched ion exchange(ESIX) of the NiHCF film for the separation of Pb2+ from aqueous solutions was investigated.In 0.1 mol/L Pb(NO3)2 solution,cyclic voltammetry(CV) combined with electrochemical quartz crystal microbalance(EQCM) technique was used to investigate the electroactive,reversibility of the film electrodes and the mechanism of ion exchange.The electrochemical behavior of NiHCF film electrodes was also compared with that in Co(NO3)2 and Ni(NO3)2 solutions.The ion selectivity of the film was investigated in 0.1 mol/L mixture solution containing [Pb(NO3)2+Co(NO3)2] and [Pb(NO3)2+Ni(NO3)2],respectively.The elementary composition of NiHCF films in reduced and oxidized form were also characterized by energy dispersive X-ray spectroscopy(EDS).The results show that the electroactive NiHCF films have reversible electrochemical behavior in aqueous solutions containing Pb2+,Co2+ and Ni2+,respectively.NiHCF film electrodes display a high Pb2+ selectivity in both Pb2+/Co2+ and Pb2+/Ni2+ binary mixtures and Pb2+ can be separated effectively from aqueous solutions by ESIX processes.