Strontium(II) adsorption on Sb(III)/Sb2O5

Abstract

The rapid development of the nuclear power plants (NPPs) in China leads to an increasing attention to the treatment of low-level radioactive wastewater (LLRW). One of the possibilities is the application of antimony pentoxide based ion exchange materials, which can exhibit effective adsorption of 90Sr. In this paper, a novel sorbent Sb(III)/Sb2O5 is prepared by sol–gel method and its structure and surface properties are determined by X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), zeta potential, surface area and porosity analysis. The batch experiments demonstrate a very efficient and selective Sr(II) elimination over a wide pH range from 2.0 to 12.0. At Sb(III)/Sb (total) ratio of 0.41, the optimum adsorption can be achieved with Kd value of 8.8×108mL/g. The co-existing calcium ions can affect the adsorption of strontium, since the Kd value drops to 103–102mL/g with calcium concentration increases to 0.1mol/L. Compared with divalent cations, the monovalent cations like Na+ and K+ have only minor influence. The strontium adsorption isotherm coincides very well with Freundlich model. The KF values are 10.7mg/g at 283K, 23.2mg/g at 303K, and 40.6mg/g at 323K. The thermodynamic studies reveal an endothermic and spontaneous process. The kinetic performance follows the pseudo-second-order adsorption model, with intra particle diffusion as the rate controlling step.