Efficient uranium(VI) recovery from fluorinated wastewater via deferiprone ligand complexation

Abstract

Extracting uranium (U(VI)) from fluoride-rich radioactive wastewater is of great significance for the development of nuclear energy and environmental remediation. The presence of thermodynamically stable [UO₂F_n]²⁻ⁿ (n= 0, 1, 2, 3, 4) aqueous complexes in fluoride-rich U(VI)-containing wastewater significantly hinders the efficiency of uranyl extraction and recovery using conventional methods. In this study, we report a direct precipitation method using deferiprone ligands for efficient uranyl extraction from fluoride-rich wastewater that offsets the preparation of solid materials. The deferiprone ligands exhibited exceptional chelating ability competing toward F⁻. In simulated 2.1 × 10^-4 mol/L U(VI) wastewater with F⁻ concentrations ranging from 1 to 10 g/L, adjusting the amount of deferiprone ligands enabled a high U(Ⅵ) precipitation rate of 97.60% to 86.90%, correspondingly. A remarkable 99.71% recovery of U(Ⅵ) from real fluoride-rich alkaline wastewater was achieved within 2 hours. Detailed investigations revealed that the competitive chelating by deferiprone ligands results in the formation of insoluble U(VI)-deferiprone complexes ([(UO₂)(H₂O)(C₇NO₂H₈)₂]·4H₂O), driven by π-π stacking interactions, electrostatic attractions, and intermolecular hydrogen bonds. Given the cost-efficiency and excellent radiation resistance of deferiprone ligands, this efficient and straightforward precipitation approach holds great promise for practical applications in U(VI) remediation and resource recovery from fluoride-rich wastewater.