Immobilization of uranium into magnetite from aqueous solution by electrodepositing approach

Highlights: • Incorporating uranium into magnetite by electrodepositing method was proposed. • Process parameters were investigated. • The mechanism of incorporating uranium was discussed. • Uranium-containing precipitate has environmental stability and can be used as resource. - Abstract: Immobilization of uranium into magnetite (Fe₃O₄), which was generated from metallic iron by electrochemical method, was proposed to rapidly remove uranium from aqueous solution. The effects of electrochemical parameters such as electrode materials, voltage, electrode gap, reaction time and pH value on the crystallization of Fe₃O₄ and uranium removal efficiencies were investigated. More than 90% uranium in the solution was precipitated with Fe₃O₄ under laboratory conditions when uranium concentration range from 0.5 mg/L to 10 mg/L. The Fe₃O₄ crystallization mechanism and immobilization of uranium was proved by XPS, XRD, TEM, FTIR and VSM methods. The results indicated that the cationic (including Fe²⁺, Fe³⁺ and U(VI)) migrate to cathode side under the electric field and the uranium was incorporated or adsorbed by Fe₃O₄ which was generated at cathode while the pH ranges between 2-7. The uranium-containing precipitate of Fe₃O₄ can exist stably at the acid concentration below 60 g/L. Furthermore, the precipitate may be used as valuable resources for uranium or iron recycling, which resulted in no secondary pollution in the removal of uranium from aqueous solution.