Tailored Crown Ether‐Based Cationic Polymer Networks for Selective Sequestration of ⁹⁹ TcO ₄ ⁻ /ReO ₄ ⁻ from Alkaline Radioactive Wastewater

ABSTRACT The efficient removal of 99 TcO 4 − from alkaline radioactive wastewater is pivotal to the long‐term safe management of nuclear waste and the sustainable development of nuclear energy. Conventional adsorbents mainly depend on ion exchange for 99 TcO 4 − removal, yet they often exhibit insufficient stability and adsorption capacity. Herein, a “dual‐reinforcement” strategy is proposed to construct an ultra‐stable cationic polymer networks (CPN‐crown) that incorporates both imidazolium cations and crown ether units via polymerization. The CPN‐crown offers multiple cooperative adsorption sites, generating a synergistic effect between ion exchange and ion‐pair interactions that markedly enhances 99 TcO 4 − capture efficiency. Compared with CPN‐phenyl containing only imidazolium sites, the introduction of crown ether markedly improves adsorption capacity under strongly alkaline conditions, achieving 354.43 mg g −1 at 5 m NaOH environment and surpassing most reported materials. CPN‐crown also demonstrates exceptional selectivity even in the presence of excess competing anions such as Cl − , NO 3 − , SO 4 2− , and PO 4 3− . Column experiments further confirmed its robust adsorption performance under strongly alkaline conditions and in simulated Hanford low‐activity waste. These findings underscore the remarkable alkaline‐resistant adsorption performance of CPN‐crown toward 99 TcO 4 − . This synergistic strategy offers valuable insights and practical guidance for the rational design of high‐performance CPNs tailored for radioactive wastewater treatment.