Selective immobilization of iodide onto a novel bismuth-impregnated layered mixed metal oxide: Batch and EXAFS studies

A novel Mg/Al/Bi ternary mixed metal oxide (MMO) was successfully prepared by a simple coprecipitation and calcination process. The Mg/Al/Bi MMO (molar ratio = 3:0.4:0.6) presented synergistically enhanced adsorption efficiency for iodide in water with porous structure. Kinetic adsorption results indicated good agreement with pseudo first-order-kinetic model (R = 0.998) and the maximum adsorption capacity calculated by Langmuir isotherm of Mg/Al/Bi MMO was 202.2 mg/g, which is higher than that of Mg/Al layered double oxide (LDO) (161.0 mg/g) and bismuth oxide (57.5 mg/g). In addition, the Mg/Al/Bi MMO showed good adsorption efficiency under neutral condition (pH 7), by which the material exhibits relatively strong resistance to the presence of co-existing anions in water due to the ion selectivity. Extended X-ray absorption fine structure (EXAFS) spectra revealed that the enhanced adsorption of iodide by Mg/Al/Bi MMO can be induced by selective Bi-O-IBformation, which is stable waste form for its treatment. Consequently, it is clear that the novel Mg/Al/Bi MMO is a potentially attractive material in terms of selective uptake of iodide with forming stable chemical complex in radioactive contaminants.