Electro-adsorption of Cs(I) ions from aqueous solution by capacitive deionization using ACC/MoO3 composite electrode

Abstract

The separation of Cs+ from radioactive wastes is of paramount importance, but still a challenge. In this paper, ACC/MoO3 composite electrode was prepared and used for the separation of Cs+ by capacitive deionization (CDI). The electrode materials were characterized by SEM-EDS, FTIR, XPS before and after adsorption experiments. The composite electrode was composed of ACC and hexagonal tunnel structure of MoO3, which had a mesoporous structure. The specific surface area, average pore diameter, total pore volume and maximal specific capacitance were 170.4 m2 g−1, 2.127 nm, 0.906 cm3 g−1 and 76.3 F g−1, respectively. The adsorption kinetics, isotherms, and the mass transfer process were analyzed, and the possible adsorption mechanism was proposed. The removal efficiency of Cs+ increased with the increase of voltage and the decrease of Cs+ concentration, which reached 44.7 % after 240 min when voltage was 1.2 V and Cs+ concentration was 5 mg L−1. The Cs+ adsorption onto the ACC/MoO3 composite was multi-layer adsorption and the adsorption to active sites (AAS) was the rate-limiting step. Overall, the ACC/MoO3 composite was a potential electrode for Cs+ separation.