Removal of strontium(II) and cobalt(II) from acidic solution by manganese antimonate

Radioactive strontium and cobalt are two major contaminants in the low-level radioactive wastewaters (LLRWs). In this study, a manganese-antimony composite oxide (MnSb) were prepared to study the sorption behavior and the removal of Sr(II) and Co(II) from acidic wastewaters. The as-prepared MnSb was identified and characterized by X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), Transmission Electron Microscope (TEM), zeta potential, and surface analysis, and its sorption performance was tested by batch experiments. Our results suggest that the MnSb oxides, with their microcrystal rutile structures and high specific surface areas, are promising candidate for the removal of Co (K-d(Co) = 2.3 x 10(6) mL/g) and Sr (K-d(Sr) = 8.3 x 10(5) mL/g) in aqueous solutions at pH > 2. Co-existing ions, like Na+, Mg2+ and Ca2+, affect the adsorption of Co and Sr to a limited degree. Adsorption of Co and Sr onto MnSb is fast and increases with elevating operating temperature. The equilibrium isotherms of Sr and Co could be best fitted by the Freundlich model with K-F values up to 1.98 and 0.54 mmol/g for Co and Sr at 323 K, respectively. Co ions were found to be more competitive than Sr ions onto MnSb with a selectivity ratio of S(Co/Sr) = 1.8. The kinetic performance of Co and Sr could be described well by the pseudo-second order equation, and film diffusion was the rate-controlling step under our experimental conditions. (C) 2016 Elsevier B.V. All rights reserved.