Efficient separation of uranium in solution by ZnFe2O4 doped with TiO2: Adsorption behaviors and mechanism study

The spinel composite doped with TiO2 (TiO2@ZnFe2O4) was prepared via in situ fabrication and template method to extract uranium(VI) from solution. Compared with ZnFe2O4 and TiO2/ZnFe2O4, TiO2@ZnFe2O4 showed a high adsorption efficiency (98.3%) and adsorption capacity (716.2 mg g−1), which mainly related to the uniform porous structure of TiO2@ZnFe2O4. After five adsorption–desorption cycles, the removal efficiency of TiO2@ZnFe2O4 remained above 90%, indicating that TiO2@ZnFe2O4 had excellent reusability. Besides, TiO2@ZnFe2O4 possessed excellent adsorption selectivity for uranium(VI) in the existence of competitive ions. The Langmuir adsorption model and pseudo-second order model fitted well the adsorption process, which demonstrated that the remove behavior of uranium(VI) on TiO2@ZnFe2O4 was a monolayer chemisorption process. The extraction behavior of TiO2@ZnFe2O4 for uranium(VI) was mainly attributed to electrostatic attraction, complexation reaction and oxygen vacancy filling. This study not only provides a high efficiency adsorbent (TiO2@ZnFe2O4) for the extraction of uranium(VI) from solution but also offers a new effective way to enhance the performance of spinel composite.