Metal–Organic Framework Featuring Monodispersed Silver Cation Sites for Highly Efficient and Selective Extraction of Aqueous Iodide Anions

Efficient extraction of iodide ion (I^-), the dominant form of aquatic iodine, is crucial for both resource recovery and pollution mitigation, particularly in seawater, nuclear wastewater, and drinking water. However, this remains a significant challenge due to the lack of adsorbents that simultaneously offer high affinity, fast kinetics, and reliable reusability for I^- capture. Herein, a novel cationic metal-organic framework featuring monodispersed silver (Ag⁺) sites (MOF-monoAg), which outperforms conventional Ag-loaded materials that rely on post-synthetic loading, enabling uniformly dispersed and highly accessible binding sites for selective and efficient I^- extraction, is presented. The unique Ag⁺ sites exhibit extraordinary binding affinity and utilization efficiency, achieving an exceptional distribution coefficient (K_d) of 1.16 × 10⁴ mL g^-1 and ultrafast adsorption rate of 10.48 mg g^-1 min^-1. MOF-monoAg shows a breakthrough iodine extraction capacity of 114.2 mg g^-1 in natural seawater, over 50 times the iodine concentration in seaweed, and a 98.7% removal rate for I^- in simulated nuclear wastewater. Additionally, MOF-monoAg-based membrane effectively reduces the I^- concentrations in iodine-exposed water to below drinking water standards, providing a promising solution for iodine resource recovery and iodine pollution remediation.