Adsorption of uranium by chitosan/Chlorella pyrenoidosa composite adsorbent bearing phosphate ligand

Abstract

In order to remove and recover uranium from acidic uranium-bearing wastewater in uranium mining and metallurgy. Herein, a novel chitosan/Chlorella pyrenoidosa composite adsorbent bearing phosphate ligand (CSP/CP) was designed and synthesized, demonstrating a high uranium adsorption capacity at a pH of 5 and excellent selectivity in an aqueous solution with eight coexisting ions. The CSP/CP exhibits a maximum adsorption capacity (1393.338 mg g−1) and selectivity (Su = 80.53%) for uranium, which is higher than many reported adsorbents. Mechanism analysis shows that the surface of CSP/CP is rich in hydroxyl, amino, phosphate and carboxyl groups, resulting in an excellent three-dimensional structure with active sites for high-performance uranium adsorption; U(VI) is selectively bound via ion exchanges with –COOH and –OH and through surface complexation with NH2 and PO. Furthermore, by desorption with 0.1 M Na2CO3 + 2% H2O2 at 318 K, CSP/CP can be recycled more than five times. It provides a new scientific basis for the preparation of high selectivity composite adsorbent by chitosan.