Stable mesoporous zirconium-porphyrin framework for high-capacity, selective iodine capture from gas and water

Radioactive iodine isotopes such as 129 I / 131 I present significant environmental and health risks due to their volatility, bioaccumulation, and long half-lives. In this study, we developed a mesoporous zirconium–porphyrin framework (Zr–TAPP) through coordination-driven self-assembly of Zr 4+ ions and tetra-aminophenyl porphyrin ligands. This material features a thermally stable two-dimensional layered structure, where π-conjugated porphyrin rings and Lewis-acidic Zr O clusters provide numerous adsorption sites. Zr–TAPP achieves high iodine vapor uptake of 1.78 g/g at 75 °C through chemisorption, reducing I₂ to I₃ − and immobilizing it via Zr N coordination and π-complexation. In aqueous solutions, it reaches a maximum iodide adsorption capacity of 303.8 mg/g at pH 7.0, driven by electrostatic attraction to protonated amino groups and porphyrin-mediated charge transfer. The adsorbent maintains 85 % of its capacity after five reuse cycles and shows strong selectivity over competing anions in aqueous solutions. Mechanistic analyses (the X-ray diffractometer and Raman spectroscopy) confirm a synergistic mechanism involving electron transfer, I₃ − formation, and hydrogen bonding at protonated nitrogen centers. This study presents a robust, efficient dual-phase iodine adsorbent that offers a promising solution for nuclear waste remediation.