Phosphonate and carboxylic acid co-functionalized MoS2 sheets for efficient sorption of uranium and europium: Multiple groups for broad-spectrum adsorption

Highlights: • A strategy is developed for efficient adsorption of broad-spectrum radionuclides. • The adsorbent of MoS₂ sheet is functionalized with phosphonate and carboxyl groups. • There are large capacities of 448.4 mg U/g and 171.2 mg Eu/g for the adsorbents. • The sorption involves the interaction between multiple groups and uranium/europium. • This adsorbent is promising for the radionuclide separation in wastewater treatment. - Abstract: It is significant to develop novel materials and techniques for efficient removal of radionuclides from radioactive wastes due to the radioactive and chemical toxicity. In this paper, we report a strategy for broad-spectrum adsorption of radionuclides by multiple groups-decorated adsorbents. Specifically, the adsorbents were prepared by grafting diethyl-(4-vinylbenzyl) phosphonate and maleic anhydride copolymers onto molybdenum disulfide sheets for the sorption of uranium(VI) and europium(III). The sorption efficiencies exhibited a dependency on pH, contact time and initial concentrations. The sorption reached the equilibrium within 60 min and followed a pseudo-second-order kinetic model. The maximum sorption capacities of the sorbents were 448.4 mg/g and 171.2 mg/g at pH 4.0 and 298.15 K for uranium(VI) and europium(III), respectively. The sorbent possessed a high efficiency of 98% in five sorption-desorption cycles without damage in chemical structures. XPS spectra showed that the sorption of uranium(VI) and europium(III) on the sorbents were originated from the interaction between multiple groups (such as sulfur, COOH, PO and PO) and uranium/europium. This work demonstrates that the adsorbent can be utilized as a promising material for the separation of broad-spectrum radionuclides from an aqueous solution.