Uranium Adsorption on Three Nanohydroxyapatites Under Various Biogeochemical Conditions

Uranium is a naturally occurring trace element and radionuclide. Uranium is introduced in the environment during industrial activities and nuclear energy accidents involving nuclear power plants, nuclear weapons tests, ore mining, and manufacturing, which may lead to the contamination of groundwater and soil. Hydroxyapatite (HAP) is a natural mineral with a high affinity for uranium in water. Groundwater often contains high carbonate concentrations that may affect uranium removal due to the formation of uranyl carbonate complexes. In order to understand the process of uranium removal, uranium adsorptions on three nano-HAPs were conducted under various biogeochemical conditions. Results showed that the fastest U adsorption occurred onto nano-HAP and U adsorption was strongly affected by biogeochemical conditions such as pH and the presence of carbonates, but less affected by temperature. The current study indicates that the presence of carbonates at pH’s above the neutral range in groundwater may inhibit U removal with nanohydroxyapatites.