One step synthesis of nitrogen-rich covalent organic frameworks with flexible secondary amine bonds for efficient iodide capture in aqueous solutions

<p indent="0mm">As the radioactive iodine possessed volatility and diffusibility, it needed to be properly disposed in order to prevent environmental and health risks. Recently, nitrogen-rich covalent organic frameworks (COFs) were found to have high iodine adsorption capacity, but the unstable linkages limited their application. In this work, we synthesized an amine-linked COFs with nitrogen-rich melamine unit named TABN-COF. TABN-COF exhibited a strong affinity for iodine, with an adsorption capacity of up to <sc>365 mg/g</sc> for I₃⁻ in aqueous phase. The ultra-strong stability of TABN-COF enabled it to maintain its crystallinity structure even after treatment with acids, bases, simulated seawater, reducing agents, and oxidizing agents, without compromising the removal rate of I₃⁻. These characteristics made TABN-COF promising for the adsorption of I₃⁻ in complex marine systems.