Composites based on zirconium dioxide and zirconium hydrophosphate containing graphene-like additions for removal of U(VI) compounds from water

The composites based on hydrated zirconium dioxide and zirconium hydrophosphate have been obtained. The materials contained 0.5-7% of graphene-like additions, which were obtained by chemical treatment of multiwalled carbon nanotubes (8-15 layers). The composites as well as their constituents were investigated with the XRD, FTIR, TEM, and porometric methods. When the content of carbon material is 2%, large granules (0.3-0.35 mm) are formed. GO was found to increase specific surface area of zirconium hydrophosphate and reduces it in the case of zirconium dioxide. Despite the small amount of GO additions, these composites show a growth of total sorption capacity of 12-14% in alkaline media. Sorption of cationic complexes of U(VI) under batch conditions was investigated. The composite based on zirconium hydrophosphate allows us to remove U(VI) from water practically completely in the presence of hardness ions; the highest regeneration degree is also achieved. Sorption kinetics is described by the model of pseudo-second order. The Dubinin-Raduchkevich model was applied to adsorption isotherms. As found, the mechanism of sorption is ion exchange that is accompanied by additional interaction of sorbed ions with functional groups.