Rationally designing imidazole-based coordination polymers with high adsorption capacity for removing iodine

Rationally designing a new adsorbent with highly selective and high adsorption capacity for removing I3− from water is still a significant challenge. Herein, we report an imidazole group-rich coordination polymer (CP) named Zn-Vlm6, which was constructed by the reaction of the 1-vinylimidazole (Vlm) and Zn2+ ions. Zn-Vlm6 showed excellent thermal and chemical stability (1 M HCl and 0.1 M NaOH). The abundance of positively charged imidazole groups and the free anti-anion NO3− in the backbone of Zn-Vlm6 results in strong electrostatic interactions and ion exchange between the material and the guest, in return, a high adsorption capacity for I3− (1680.7 mg g−1). In addition, the kinetics of I3− adsorption on Zn-Vlm6 followed the pseudo-second-order kinetic model and reached adsorption equilibrium within 3 min. More importantly, Zn-Vlm6 can selectively capture I3− in the presence of competing anions and selectively remove high up to 96.4% of I3− from different environments (e.g., lake water, seawater). Moreover, Zn-Vlm6 can also adsorb gaseous iodine up to 2470 mg g−1. This study shows that Zn-Vlm6 has promising applications for removing iodine in the gaseous state and from different aqueous phases.