China Nonferrous Metallurgy

The removal of uranium from water is a topic that requires research due to its harmful effects on human health. Using low-cost CaCO3 and (NH4)2HPO4 as raw materials, hydroxyapatite (OP-HAP) was synthesized in a one-pot method and applied for the removal of uranium from solutions. The adsorption performance of OP-HAP on uranium was explored through single-factor and orthogonal experiments, and its characteristics were characterized using SEM, EDS, XRD, FTIR, and XPS. The results showed that under optimal conditions, OP-HAP achieved a maximum removal rate of around 97% for 10mg·L-1 uranium, with a fitted maximum adsorption capacity of 1584.79mg·g-1. The adsorption process of uranium by OP-HAP followed the Langmuir isotherm adsorption model and the pseudo-second-order kinetic model. Thermodynamic studies indicated that the adsorption process was endothermic and spontaneous. Characterization of the Zeta potential and OP-HAP before and after uranium adsorption revealed that the main mechanisms of adsorption were electrostatic adsorption, ion exchange, complexation, and dissolution precipitation. OP-HAP exhibited a high adsorption capacity for uranium and is a potential uranium adsorbent.