Cationic covalent organic frameworks based on pyridine and triazine for selective extraction of radioactive 99TcO4- from contaminated water

• Published in: Separation and purification technology Vol. 354; p. 128786
• Main Authors: Tang, Qing, Wu, Qun-Yan, Shi, Wei-Qun, Han, Gang, Pan, Xiao-Han, Jin, Ming-Jie, Zheng, De-Rui, Zhou, Guang-Ze-Guo, Zu, Jian-Hua
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.02.2025
• Subjects: 99TcO4-/ReO4; Covalent organic frameworks; Ion exchange; Radioactive wastewater; Selective removal; Covalent organic frameworks; Selective removal; Ion exchange; Radioactive wastewater; 99TcO4-/ReO4
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2024.128786

[Display omitted] •A cationic covalent organic framework with triazine and pyridine (COF-Tys) is designed by directly introducing quaternary ammonium.•COF-Tys demonstrates excellent chemical stability and radiation resistance.•COF-Tys exhibits high efficiency and remarkable selectivity in capturing 99TcO4-/ReO4- from diverse contaminated water.•The predominant adsorption mechanism for 99TcO4-/ReO4- is proved to be anion exchange. Efficient elimination of 99TcO4- is crucial for radioactive waste management and environmental protection, but achieving outstanding stability and high selectivity remains a major challenge for the reported adsorbents. In this study, we report a cationic covalent organic framework based on pyridine and triazine (COF-Tys) for the selective extraction of 99TcO4-/ReO4- (a non-radioactive surrogate of 99TcO4-). COF-Tys exhibits excellent stability under acidic or irradiation conditions. Experimental results reveal that COF-Tys possesses high adsorption capacity (422.61 mg/g for ReO4-), rapid kinetics (removing over 99% of 99TcO4- within 5 min), and promising recyclability (less than a 1.5% decrease in ReO4- removal after five adsorption/desorption cycles). Notably, COF-Tys demonstrates remarkable selectivity, adsorbing more than 90% of 99TcO4- even in simulated radioactive solutions with excess competing ions. Furthermore, COF-Tys achieves 97.5% and 80.4% removal of 99TcO4- from contaminated groundwater and seawater within 10 min, respectively. Energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses confirm that the primary mechanism of 99TcO4-/ReO4- adsorption involves anion exchange between Cl- and 99TcO4-/ReO4-. In conclusion, COF-Tys holds tremendous potential as a high-performance adsorbent for the separationof 99TcO4- from radioactive wastewater.