Creation of Cationic Polymeric Nanotrap Featuring High Anion Density and Exceptional Alkaline Stability for Highly...

There is an urgent need for highly efficient sorbents capable of selectively removing ⁹⁹TcO₄^- from concentrated alkaline nuclear wastes, which has long been a significant challenge. In this study, we present the design and synthesis of a high-performance adsorbent, CPN-3 (CPN denotes cationic polymeric nanotrap), which achieves excellent ⁹⁹TcO₄^- capture under strong alkaline conditions by incorporating branched alkyl chains on the N3 position of imidazolium units and optimizing the framework anion density within the pores of a cationic polymeric nanotrap. CPN-3 features exceptional stability in harsh alkaline and radioactive environments as well as exhibits fast kinetics, high adsorption capacity, and outstanding selectivity with full reusability and great potential for the cost-effective removal of ⁹⁹TcO₄^-/ReO₄^- from contaminated water. Notably, CPN-3 marks a record-high adsorption capacity of 1052 mg/g for ReO₄^- after treatment with 1 M NaOH aqueous solutions for 24 h and demonstrates a rapid removal rate for ⁹⁹TcO₄^- from simulated Hanford and Savannah River Site waste streams. The mechanisms for the superior alkaline stability and ⁹⁹TcO₄^- capture performances of CPN-3 are investigated through combined experimental and computational studies. This work suggests an alternative perspective for designing functional materials to address nuclear waste management.