Electro-adsorption of Sr(II) from aqueous solution by activated carbon cloth/nickel hexacyanoferrate composite electrode through capacitive deionization

The activated carbon cloth/nickel hexacyanoferrate (ACC/NiHCF) electrode was successfully synthesized by a co-precipitation method, and the performance was comprehensively evaluated as CDI electrode materials for Sr2+ removal. The as-prepared ACC/NiHCF electrode had the mesoporous and the coordination framework structure, which provided convenient transport channels for ions or electrons. As a result, the ACC/NiHCF electrode exhibited the high Sr2+ removal efficiency. The maximum removal efficiency was 77.20% at 0.6 V in 5 mg L−1 SrCl2 solution, much higher that of pristine ACC. The isotherm models and mass transfer models suggested that the adsorption process of Sr2+ onto ACC/NiHCF was mainly through the multi-layer adsorption, and adsorption onto the active sites was the main rate-limiting step. In addition, the comprehensive characterizations elaborated the mechanism involved physic-chemical adsorption and electrostatic adsorption. Above all, ACC/NiHCF is an efficient electrode for Sr2+ removal. This study provided new insight into the fabrication of high-efficiency composite electrode materials for Sr2+ removal by CDI.