Advanced waterborne polyurethane/poly(ionic liquids) foam for highly efficient and selective adsorption of 99TcO4-/ReO4-

Abstract

The development of high-performance adsorbents for the efficient removal of radioactive Technetium-99 (⁹⁹TcO₄^-) is critical to addressing the challenges nuclear waste contamination. However, current adsorbents still face significant limitations, including low adsorption capacity, poor stability, contamination from the adsorbent itself, and difficult handling and recycling. To overcome these challenges, this study reports the successfully preparation a waterborne polyurethane/poly(ionic liquids) (WPU/PILs) foam adsorbent for selective adsorption of ⁹⁹TcO₄^- (ReO₄^- as a substitute for laboratory operation) by in-situ foaming method and its adsorption performance and underlying mechanism are comprehensively investigated. The results show that WPU/PILs-10 exhibits excellent adsorption performance with the maximum adsorption capacity of ReO₄^- up to 130.22 mg g⁻¹ (theoretical saturated adsorption capacity of 1302.20 mg g⁻¹) at pH = 7, surpassing most existing adsorbents with similar functionalities. Remarkably, WPU/PILs-10 maintains excellent recoverability and structural stability after even five adsorption–desorption cycles. Theoretical calculations and structural characterization indicate that the superior adsorption performance of WPU/PILs-10 for ⁹⁹TcO₄^-/ReO₄^- is mainly attributed to the ion-exchange interaction between Tf₂N^- in the PILs and ⁹⁹TcO₄^-/ReO₄^-. This work has the dual advantages of environmental friendliness and functional enhancement, and has potential applications in the fields of nuclear waste liquid treatment and radioactive anion adsorption.