As a critical radioactive anionic contaminant, traditional adsorbents primarily remove iodate (IO3-) through ion exchange or hard acid-hard base interactions, but suffer from limited affinity and capacity. Herein, employing the synergistic effect of ion exchange and redox, we successfully synthesized a redox-active cationic polymer network (SCU-CPN-6, [C9H10O2N5•Cl]n) by merging guanidino groups with ion-exchange capability and phenolic groups with redox ability via a Schiff base reaction. SCU-CPN-6 exhibits a groundbreaking adsorption capacity of 896 mg/g for IO3-. The inferior adsorption capacities of polymeric networks containing only redox (~0 mg/g) or ion exchange (232 mg/g) fragments underscore the synergistic "1 + 1 > 2" effect of the two mechanisms. Besides, SCU-CPN-6 shows excellent uptake selectivity for IO3- in the presence of high concentrations of SO42-, Cl-, and NO3-. Meanwhile, a high distribution coefficient indicates its exemplary deep-removal performance for low IO3- concentration. The synergic strategy not only presents a breakthrough solution for the efficient removal of IO3- but also establishes a promising avenue for the design of advanced adsorbents for diverse applications.
Keywords: adsorption capacity; cationic polymer networks; iodate; ion-exchange; redox.
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