Radiation-resistant pyridinium-functionalized anion exchange resins for efficient capture of Re(VII)

Efficient removal of pertechnetate ( 99 TcO 4 − ) from nuclear wastewater is crucial for environmental protection and long-term waste management. However, many existing adsorbents suffer from exhibiting limited selectivity and insufficient chemical or radiation stability under the harsh conditions typical of nuclear effluents. Here, we report a series of pyridinium and methylpyridium-functionalized anion exchange resins (PMCl-Py 0 , PMCl-Py 2 , and PMCl-Py 3 ) for the selective capture of ReO 4 − as a non-radioactive analogue of 99 TcO 4 − . These resins show high adsorption capacities for Re(VII) across a broad pH range (2−12) at 25 °C, reaching 701.92, 567.63, and 652.02 mg·g −1 for PMCl-Py 0 , PMCl-Py 2 , and PMCl-Py 3 , respectively. They also exhibit excellent chemical and radiation resistance, with negligible loss of Re(VII) uptake after exposure to 2 M HNO 3 , 5 M HCl, 5 M NaOH, 20% H 2 O 2 , or β/γ irradiation up to 200 kGy. Importantly, the resins present excellent selectivity. Even at ReO 4 − :NO 3 − or ReO 4 − :SO 4 2− molar ratios of 1:1000, PMCl-Py 3 retains high removal efficiencies of 63.48% and 97.81%, respectively, outperforming the commercial nuclear-grade resin ZGANR170. In simulated Hanford low-activity waste, PMCl-Py 3 achieves 95.87% removal of ReO 4 − . Dynamic adsorption experiments indicate that PMCl-Py 3 has a favorable industrial application prospect (dynamic adsorption capacity 545.94 mg·g −1 ). Spectroscopic analysis and DFT calculations indicate that the adsorption process is achieved through a synergistic mechanism of N + electrostatic attraction and C-H⋯O/Cl − hydrogen bonds. Owing to their outstanding adsorption performance, these pyridinium-based anion exchange resins are promising candidates for the practical remediation of 99 Tc-contaminated nuclear wastewater.