Efficient Separation of Uranium in Solution by ZnFe₂O₄ Doped with ZrO₂: Adsorption Behaviors and Mechanism Study

In order to solve the problem of uranium pollution during the development and application of nuclear energy, magnetic ZnFe₂O₄/ZrO₂(ZFOZO) composite material was synthesized by hydrothermal method to treat uranium containing wastewater. In this study, the surface properties and mechanism of the synthesized ZFOZO were analyzed by various characterization methods. The effects of adsorption time, pH, dosage of adsorbent, coexisting ions, and initial concentration of uranium (VI) solution on the adsorption performance of uranium (VI) by ZFOZO were investigated. ZFOZO exhibited the maximum adsorption rate of 99.8% under the conditions of C_U (VI) = 10 mg/L, pH = 6, M/V = 0.3g/L, t =120 min, and T = 303K. The adsorption process was found to be a spontaneous endothermic process and conformed to the pseudo-second-order kinetic model and the Freundlich isothermal adsorption model. The adsorption mechanism of ZFOZO on U (VI) is mainly electrostatic adsorption, surface complexation, and oxygen vacancy. The maximum adsorption capacity of ZFOZO for U (VI) can reach 552.36mg/g. Adsorption–desorption experiment demonstrated that ZFOZO has a good reusability, after five cycles of adsorption and desorption, the adsorption efficiency is still above 75%. Cu²⁺ and Fe³⁺ will produce competitive adsorption and reduce the adsorption performance of ZFOZO on U (VI). In summary, this study provides a high efficiency, low cost, and rapid recovery adsorbent for the treatment of uranium containing wastewater in the future.