Performance and mechanism of biochar loaded magnetic nanocarbon hydroxyapatite(CHAP-γ-Fe₂O₃/BC) for the removal of U(Ⅵ) from water

To address the efficiency of removing U(Ⅵ) from water using functional materials and the susceptibility of nanoparticles to agglomeration, biochar-loaded magnetic nanocarbon hydroxyapatite (CHAP-γ-Fe₂O₃/BC) composites were prepared by dynamic oil-heating and impregnation methods using corn stover, egg shells, and magnetic γ-Fe₂O, and the experiments were carried out to investigate the performances and used for the removal of U(Ⅵ) from water. When the initial concentration of U(Ⅵ) is 5 mg/L, the dosage of CHAP-γ-Fe₂O₃/BC is 0.1 g/L, the pH value is 6, the temperature is 30℃, and the reaction time is 1 h, the experimental results show that the maximum adsorption capacity of CHAP-γ-Fe₂O₃/BC for U(Ⅵ) reaches 324.4 mg/g, and the removal rate reaches 95.93%. The proposed secondary kinetic model and Langmuir model could fit the adsorption process of CHAP-γ-Fe₂O₃/BC on U(Ⅵ) better, indicating that the monomolecular layer chemisorption is dominated. The materials are realized to attenuate the agglomeration by surface modification technique. The composite material shows good separation recovery and recyclability in the magnetic field. The characterization results of FTIR and XPS prove that the removal mechanism of uranium by this material mainly includes ion exchange, dissolution-precipitation chemisorption and surface complexation.