A hydrophobic imidazolium cationic framework for selective adsorption of TcO4−/ReO4− from aqueous solutions

Abstract

Traditional anion exchangers for TcO₄⁻ usually have low selectivity and adsorption capacity due to the lack of functional groups that interact strongly with TcO₄⁻. Here, we report a three-dimensional imidazolium network IMI-P that exhibits high adsorption capacity, fast kinetics, and outstanding selectivity for ReO₄⁻/TcO₄⁻ at pH 2–13. It can remove 90% of ReO₄⁻ in 30 s and 99% ReO₄⁻ in 10 min, which is significantly faster than most commercial materials. Besides, the maximum sorption capacity of IMI-P (792 mg ReO₄⁻/g) is also higher than that of most commercial materials. IMI-P shows good TcO₄⁻ removal efficiencies for simulated wastewater, which can reach 91.5% and 98.4% at the solid–liquid ratio of 10 g L⁻¹ and 50 g L⁻¹, respectively. Compared with other Tc-adsorption polymers, IMI-P with a larger particle size (10–30 μm) is more suitable for column chromatography separation. Therefore, IMI-P has important application potential in wastewater treatment in the nuclear industry. The adsorption mechanism of IMI-P and the interaction mode with ReO₄⁻ were also studied by IR, EDS, and XPS.