Preparation of novel polyvinyl alcohol–carbon nanotubes containing imidazolyl ionic liquid/chitosan hydrogel for highly efficient uranium extraction from seawater

A novel polyvinyl alcohol–carbon nanotube containing an imidazolyl ionic liquid/chitosan composite hydrogel (termed CBCS) was prepared for highly selective uranium adsorption from seawater. The results show that CBCS has good adsorption properties for uranium within the pH range of 5.0–8.0. Kinetics and thermodynamics experiments show that the theoretical maximum adsorption capacity of CBCS to U(VI) is 496.049 mg/g (288 K, pH = 6.0), indicating a spontaneous exothermic reaction. Mechanism analysis shows that the hydroxyl group, amino group, and CN bond on the surface of CBCS directly participate in uranium adsorption and that the dense pores on the surface of CBCS play an important role in uranium adsorption. The competitive adsorption experiment shows that CBCS has excellent uranium adsorption selectivity. In addition, CBCS exhibits good reusability. After five adsorption–desorption cycles, the uranium adsorption rate of CBCS can still reach >98 %. Hence, CBCS has excellent potential for uranium extraction from seawater. •Hydroxyl group, amino group, and CN bond on the surface of CBCS participate in uranium adsorption•The distribution coefficient of CBCS for uranium is significantly higher than that for vanadium.•The uranium adsorption rate of CBCS can reach >90 % at pH 5.0–8.0.