Effect of doping cation on the adsorption properties of hydroxyapatite to uranium

Hydroxyapatite samples doped with different metal ions (HAP-M, M ​= ​Cu, Sr, Al, Ce, and Ti) were successfully prepared by a simple co-precipitation method for effective U(VI) uptake. The applications of HAP-M in capturing U(VI) were investigated. Besides, numerous characterizations were taken to study the chemical and physical properties of HAP-M. The critical factors affecting U(VI) adsorption were examined, such as pH, contact time, initial concentration of U(VI) and solution temperature. The present study revealed that the adsorption effect of HAP for U(VI) can be affected by doping metal cations with different ionic radii, and HAP doping with Ti4+ ions increased its adsorption selectivity to U(VI). With the increase of the molar ratio of doped Ti4+ ions (5%–20%), the adsorption selection of U(VI) on HAP-Ti is also gradually increasing. HAP-Ti is a potentially efficient adsorbent in removing U(VI) from radioactive solutions.