Fast removal of strontium from nitric acid solution using an acid-resistant silica-based adsorbent

To efficiently separate strontium (Sr) from simulated high level liquid waste (HLLW), a novel acid-resistant inorganic-organic hybrid adsorbent, named as HEMAP/SiO2-P, was prepared by loading 2-hydroxyethyl-2-methyl-2-propenoate phosphate (HEMAP) into styrene-divinylbenzene modified silica (SiO2-P) with vacuum impregnation method. The experimental results showed that the adsorbent exhibited good adsorption selectivity with the SFSr/metal ions over 64.2 in 3 M HNO3 simulated HLLW. In addition, the adsorption of Sr by the adsorbent was in accordance with the pseudo-second-order kinetic model and the Langmuir isotherm model, and the adsorption equilibrium was obtained within 1 min with the saturation adsorption capacity of 61.2 mg/g. The adsorption of Sr was not markedly changed with increasing temperature. Furthermore, the results of adsorption experiments, characterization analysis, extraction experiments and density functional theory (DFT) calculations revealed that two organic ligand molecules were coordinated with one Sr molecule and simultaneously involved two nitrate molecules to maintain the charge balance during the adsorption process.