Mechanism of iodine release from iodoapatite in aqueous solution

摘要: Safe disposal of nuclear waste is essential to ensure the sustainability energy. This especially true for volatile radionuclide iodine-129 due its long half-life (15.7 Ma) and high mobility in most environments. The dissolution behaviour lead vanadium iodoapatite (Pb5(VO4)3I) synthesized evaluate possible use immobilizing was investigated understand mechanism by which iodide released. Experiments using a semi-dynamic method were carried out cap-sealed Teflon vessels at constant temperature 90 ± 0.5 °C with fixed sample surface area-to-solution volume ratio 16 m−1. leachates analyzed inductively coupled plasma mass spectrometry (ICP-MS) leached surfaces examined X-ray diffraction (XRD), scanning electron microscopy (SEM) infrared spectroscopy (IR). results show that dissolved congruently rate, while iodine initially released significantly higher rate than suggested stoichiometry respect vanadium. iodine-to-lead molar solution gradually decreased over time, but release remained superstoichiometric. suggest occurs an ion-exchange process faster Pb–V–O framework. Analysis samples shows spectroscopic signature OH groups consistent ion exchange mechanism.