Design of amidoximized hydroxyapatite for extracting uranium from seawater

Extracting uranium from natural seawater is a huge challenge because of the complex environment of seawater and extremely low uranium concentration. In this work, amidoximized hydroxyapatite (AO-HAP) was prepared to capture uranium from seawater. The introduction of amidoxime group greatly improved the recognition ability of AO-HAP for uranium in neutral and weakly alkaline environment (pH = 7-8). The uptake process of AO-HAP for uranium was fitted by Langmuir and pseudo-second-order models, suggesting that the capture behavior of AO-HAP for uranium was a homogeneous chemisorption. The saturated uranium uptake capacity of AO-HAP was 865.3 mg g-1 from aqueous solution, which was better than most of other reported uranium extractants. More importantly, AO-HAP had good regeneration ability and excellent adsorption performance in natural seawater (6.25 mg g-1 in 30 days). In sum, AO-HAP is a highly potential candidate as adsorbent material for the efficient extraction of uranium from seawater.