Choline hydroxide‑functionalized silica aerogel for efficient capture and immobilization of radioactive iodine vapor

Improper treatment of radioactive iodine vapor generated during spent fuel reprocessing can lead to significant environmental hazards. This study aims to synthesize a choline hydroxide-functionalized silica aerogel composite material (CH-Si aerogel) to enhance iodine capture through hydroxyl-induced polarization of iodine molecules. The polarized iodine subsequently forms polyiodide anions, which are effectively captured via electrostatic interactions with the positively charged quaternary ammonium nitrogen centers. The results indicate that CH-Si aerogel achieves an iodine adsorption capacity of up to 1362.43 mg/g, significantly surpassing previously reported silica-based adsorbents. DFT calculations reveal that hydroxyl groups substantially enhance the polarization of iodine molecules, leading to changes in the electron density at the adsorption sites. Furthermore, the quaternary ammonium nitrogen centers interact with polyiodide anions through electrostatic adsorption, reinforcing the material’s iodine capture capability. The material exhibits adsorption energies of –1.855 eV for I 2 and –3.875 eV for polarized iodine ions, demonstrating robust stability and excellent adsorption performance. In addition, CH‑Si aerogel maintains excellent iodine capture capacity even under complex conditions of high humidity (RH=50 %) and highly humid acidic environments (pH=1). CH-Si aerogel exhibits excellent potential for practical applications, offering new insights for the development of efficient iodine capture materials.