Preparation of magnetic mesoporous TiO₂/graphene oxide composites and their adsorption for U(Ⅵ)

The magnetic mesoporous TiO₂/graphene oxide (Fe₃O₄@TiO₂/GO) composites were prepared by the synthesis of graphene oxide (GO), nano Fe₃O₄ and tetrabutyl titanate (TBOT), then the Fe₃O₄@TiO₂/GO composites were used to treat U(Ⅵ)-containing waste water at a concentration of 10 mg·L^-1. The effects of mass fraction of GO in Fe₃O₄@TiO₂/GO composites, initial pH of solution, the dosage of Fe₃O₄@TiO₂/GO composites, reaction time, initial uranium concentration and coexisting ions on U(Ⅵ) adsorption on Fe₃O₄@TiO₂/GO composites were investigated. The results show that the Fe₃O₄@TiO₂/GO composites has the best adsorption for U(Ⅵ) when the pH value is 6, the mass fraction of GO is 60wt% and the Fe₃O₄@TiO₂/GO composites dosage is 10 mg, under the same conditions, the adsorption capacity of U(Ⅵ) is 10.99 mg·g^-1 and 1.91 mg·g^-1 higher than that of Fe₃O₄@TiO₂ composites and GO, respectively. The adsorption results of the Fe₃O₄@TiO₂/GO composites are balanced at 180 min, and the pseudo-second-order kinetics model and the Freundlich adsorption isotherm model are good descriptions of the adsorption of the Fe₃O₄@TiO₂/GO composites for U(Ⅵ) process. The results of desorption experiments show that the adsorption efficiency of the Fe₃O₄@TiO₂/GO composites for U(Ⅵ) remains as high as 90.86% after 5 cycles of adsorption-desorption, indicating that the Fe₃O₄@TiO₂/GO composites have higher recycling performance.