Rapid and highly selective capture of U(VI) from water by copper phosphate

Abstract

The removal of highly hazardous U(VI)-containing contaminants of concern has been a major issue for effluent discharge and ecological protection because current some inorganic adsorbents lack ion selectivity and are economically viable. Inspired by these limitations, here we reported a simple and controlled technique for the synthesis of copper phosphate (CP) that combines chemical oxidation with in-situ precipitation, able to selectively capture uranium (VI) ions. The resulting CP has been analyzed using powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy. Adsorption experiments with U(VI) show that CP quickly adsorbs U(VI) from acidic water within 1 min, with a high removal efficiency of up to 97.8%. A maximum adsorption capacity of 1000 mgU g−1 adsorbent can be achieved at pH 3.0. Importantly, the selective adsorption experiments for a total of 11 metal ions show that the U(VI) capture is very effective, with an adsorption capacity of 1.64 mmol g−1 for U(VI) and a total adsorption capacity of 4.89 mmol g−1 for Ln-An metal ions. Finally, XRD and XPS results reveal that the underlying mechanism for U(VI) capture is driven through the dissolution-precipitation and surface complexation. Overall, this work proposes a new metal ion trapping agent that may find potential applications in the fields of water purification and environmental remediation.