Highly efficient capture and recovery of uranium by reusable layered double hydroxide intercalated with 2-mercaptoethanesulfonate

Abstract

Uranium is the main source for nuclear energy but also one of the most toxic heavy metals. It is of vital importance to develop highly selective and efficient materials for uptake of uranium (normally as UO22+) from radioactive wastewater and from seawater. 2-Mercaptoethanesulfonate intercalated layered double hydroxide (MS-LDH) nanosheets were prepared and successfully applied as an effective adsorbent material for the efficient and selective uptake of uranium(VI) ions from an aqueous solution. The very high adsorption capacity of 657.89 mg g−1 and distribution coefficients of ∼108 mL g−1 place the MS-LDH at the top of materials known for uptake of U(VI). For the U(VI), an exceptionally rapid adsorption with 96.0% uptake within 10 min, 99.2% uptake within 20 min, and ∼100% uptake within 45 min was observed. In addition, MS-LDH exhibits superior selectivity and higher adsorption capacity for U(VI) ions in the presence of high concentration levels of competitive ions such as Na+, K+, Ca2+, and Mg2+. The UO22+⋯S2− interactions are the basis for the high selectivity. The adsorption kinetic curves for U(VI) fitted well with the pseudo-second order model, suggesting a chemical adsorption mechanism via MS and MSO4 bindings. The results presented the exceptional potential of MS-LDH for recovery of uranium from uranium-containing wastes, groundwater, and seawater.