Highly efficient adsorption of U(VI) from aqueous solution by the terpolymer of acrylonitrile/acrylic acid-co-hydroxyapatite

To better eliminate the impact of radioactive elements on the environment, we synthesized a ter -polymer of acrylonitrile, acrylic acid, and hydroxyapatite (AN/AA-co-HAP) as an adsorption mate-rial for separating uranyl ions in aqueous solution, which was based on our previous work. We used Fourier-transform infrared spectroscopy, scanning electron microscopy, elemental analysis, N2 sorption/desorption isotherm, thermogravimetric analysis and X-ray diffraction methods to characterize the material's structure, and studied the effect of equilibrium time, pH, ionic strength, solid-liquid ratio, initial concentration, and temperature on the adsorption process. Finally, it is con-cluded that adsorption equilibrium can be reached within 60 min at room temperature, and the maximum adsorption capacity is 343.3 mg/g. Thermodynamic analysis indicates that the adsorption process is a spontaneous endothermic process. In the system with a nitric acid concentration of 0.05 mol/L (pH value: 1.3), the desorption rate of U(VI) can reach 91%, while the adsorption rate of U(VI) in aqueous solution onto AN/AA-co-HAP is still remains >60% even after the material is has been reused 6 times. These results suggest that AN/AA-co-HAP is highly valuable for treating U(VI) ions in aqueous solution.