Abstract
Hydrophobic zeolites have been identified as suitable adsorbents for capturing radioactive iodine species from nuclear-power-plant off-gas because of their high stability and strong water resistance. However, only the most common zeolites have been investigated for the capture of molecular iodine to date. Herein, we demonstrate that the composition and pore structure of zeolites considerably affect their iodine adsorption performance. A novel all-silica ExxonMobil material-17 (EMM-17) zeolite having a unique three-dimensional 10(12) x 10(12) x 11-ring channel system exhibits a high adsorption capacity for iodine and methyl iodide in the presence of water. EMM-17 outperforms previously reported zeolites in terms of gravimetric and volumetric adsorption capacity in dynamic adsorption measurements. The excellent iodine/methyl iodide capture properties are attributed to the combination of optimal pore size, high pore volume, strong hydrophobicity, and suitable particle morphology. This study provides useful insights for designing efficient adsorbents for iodine capture.