Research Progress on Adsorption of Radioactive Iodine from Water by Covalent Organic Frameworks
The rapid expansion of the nuclear power industry has increased the demand for effective nuclear wastewater treatment, making the efficient removal of radioactive iodine isotopes (e.g., 131I, 129I) from aqueous environments a critical challenge. Covalent organic frameworks (COFs), a class of crystalline porous materials characterized by high specific surface area, tunable pore structures, and exceptional stability, exhibit significant potential for capturing radioactive iodine from water. This review systematically examines the adsorption mechanisms of iodine by COF materials, including electrostatic interactions, charge transfer, hydrogen bonding, and secondary mechanisms such as metal coordination, ion exchange, and van der Waals forces. The effects of COF pore structures on iodine removal efficacy are discussed with a focus on pore size and functional group modifications. Key research trends and prevailing challenges in the application of COFs for aqueous iodine capture are analyzed, including the need for selective adsorption in complex wastewater matrices and the scalability of COF synthesis. The review concludes with a perspective on future research directions, emphasizing the design of novel COFs with tailored pore chemistry and the development of cost-effective, regenerable adsorbents for practical deployment in nuclear wastewater treatment.