Sorption of U(VI) onto ZrSiO₄gamma irradiated and functionalized with phytic acid

In the suitability assessment of candidate materials as engineering barriers for a Deep Geological Repository (DGR), new studies concerned with zirconium silicate have been carried out. The zirconium silicate extracted from beach sand, was submitted to gamma irradiation in order to evaluate its structural stability and then functionalized with phytic acid (IP6) and measured its sorption capacity vis-a-vis uranium. The purified, irradiated and functionalized material was then characterized by several analytical techniques. The surface parameters including the surface area and density of surface sites were also determined. The results obtained from physic-chemical characterization showed that there were no significant changes in the structure of zirconium silicate after its gamma-irradiation. These results are consistent with those of sorption experiments. Uranium (VI) sorption capacity of zirconium silicate is increased in the presence of phytic acid and remained constant after its exposition to high doses of gamma-radiation (10 and 30 MGy). These results show that the IP6-functionalized zirconium silicate can be used as engineering barriers for a DGR.