Nanoscale composites of hydroxyapatite coated with zero valent iron: preparation, characterization and uranium removal

Herein, a practical and simple reduction method was used to prepared the nanoscale composites of hydroxyapatite (HAP) coated with zero valent iron for uranium (U) efficient removal. The effects of the ratio of HAP, the dosage of the composites, pH value, contact time, initial concentration of U, temperature, and ions concentration of Mn2+ and CO32− on U adsorption were investigated, respectively. The maximum removal amount of the composites amounted to 155.8 mg g−1 when the initial pH was 4.0, temperature 298 K, and contact time 150 min. The removal process was analyzed by isotherms, kinetics, and thermodynamics. The relationship between adsorption capacity qe and equilibrium concentration Ce could be well described by a pseudo-second-order, intra-particle diffusion model and Langmuir isotherms. The synthesized composite is promising for efficiently treating U-contaminated groundwater.