Influence of Interfering Ions and Adsorption Temperature on Radioactive Iodine Removal Efficiency and Stability of Ni-MOF-74 and Zr-UiO-66

Metal-organic frameworks (MOFs) often exhibitan exceptionaladsorption-based separation performance for a variety of gases, ions,and liquids. While most radioactive iodine removal studies focuson the capture of radioactive iodine from off-gas streams, few studieshave systematically investigated the effect of structure-propertyrelationships of MOFs on iodine removal performance in the presenceof interfering ions in liquid solutions. Herein, we investigated theiodide ion (I-) adsorption performance of two modelMOFs (e.g., Ni-MOF-74 and Zr-UiO-66) in liquid phase as a functionof iodine concentration (e.g., 0.125 to 0.25 and 0.50 mmol/L) andadsorption temperature (e.g., 25 to 40 and 60 & DEG;C), and in thepresence of interfering ions such as Cl- and CO3 (2-) through batch-mode experiments. Underidentical experimental conditions, Ni-MOF-74 outperformed Zr-UiO-66in immobilizing iodine from the solution by achieving a maximum iodineremoval efficiency of 97% at 60 & DEG;C. The results showed that thepresence of other interfering ions marginally affects the iodine removalefficiency (e.g., capacity and rate of iodine capture) over both MOFadsorbents. The adsorption kinetics was found to be controlled bymultiple transport processes encompassing external surface adsorption,intraparticle diffusion, and final equilibrium. Moreover, the leachtest results revealed 8 and 12% iodine release from Ni-MOF-74 andZr-UiO-66, respectively, at 25 & DEG;C after 48 h aging. This studyestablishes guiding principles for sustainable removal of iodine inthe presence of Cl- and CO3 (2-) species in cyclohexane.