Calcium phosphate-modified magnetic Fe ₃ O ₄ for enhanced uranium adsorption performance

Abstract The urgent need for addressing uranium pollution caused by nuclear energy development has driven research into efficient remediation strategies. In this work, a Fe 3 O 4 @calcium phosphate (CPO) composite was successfully synthesized via a combination of hydrothermal and reflux method. Characterization data confirmed that the composite integrates the superparamagnetism of Fe 3 O 4 with the highly active phosphate groups of CPO. Adsorption performance tests revealed that at pH = 5.0, the composite exhibits a saturation adsorption capacity of 167.53 mg g −1 for U(VI), which is 7.7 times higher than that of pure Fe 3 O 4 , with adsorption equilibrium achieved within 16 min. Fitting results from the Langmuir isotherm model and kinetic models indicated that the adsorption process is dominated by monolayer adsorption. Test analysis confirmed that phosphate groups in CPO selectively captured U(VI) through complexation, and the Fe 3 O 4 @CPO composite could be rapidly separated via an external magnetic field. This composite provided a solution that integrated excellent adsorption performance and convenient separability for the efficient remediation of uranium-contaminated water.