Fine-tuning of ZIF-67 pore sizes via ligand exchange: optimal active site interactions for iodine capture

Abstract

Radioactive iodine isotopes such as ¹²⁹I and ¹³¹I exhibit high volatility and a tendency to bioaccumulate in marine organisms, ultimately affecting human health through the food chain. Addressing the environmental challenges posed by persistent and mobile radioactive iodine species, this study develops a cost-effective adsorbent through strategic ligand engineering. ZIF-67-IM was synthesized by partial ligand substitution of 2-methylimidazole (2-MIM) with imidazole (IM) ligands in ZIF-67, and N₂ adsorption–desorption results show the micro porosity of defect ZIF-67-IM materials with large surface areas. For liquid-phase iodine (non-radioactive ¹²⁷I₂) capture, ZIF-67-IM exhibits an adsorption capacity of 864.9 mg g⁻¹ and a removal efficiency of 96.1%.