Mechanistic impact of organics on electro-induced transformation of iron oxides and simultaneous uranium immobilization in wastewater

Abstract

The incorporation of uranium into the magnetite generated through via electrochemical methods represents a sustainable strategy for remediation of uranium-contaminated organic wastewater. Nevertheless, the influence mechanisms of organics on this treatment process remain insufficiently understood. This study used an electrochemical system featuring iron and graphite electrodes along with sodium chloride as the electrolyte to investigate the impact of various organics on uranium removal. The results showed that disodium ethylenediaminetetraacetate addition delayed magnetite formation, resulting in a final product with a mixture of various iron oxides. However, this alteration did not significantly affect the mechanism and efficiency of uranium removal. In contrast, the introduction of oxalate reduced the particle size of magnetite, thereby shifting the primary mechanism of uranium removal towards adsorption, which results in a slight decrease in removal efficiency. Notably, due to the chelation properties of citrate, which nearly eliminate Fe(II) in the solution, magnetite formation was inhibited, thereby substantially reducing the final uranium removal. A 200-day leaching experiment demonstrated that the structural integrity of the synthesized mineral is predominantly maintained. This study elucidates the impact of common organics on the electrochemical mineralization system for uranium removal and offers theoretical guidance for the treatment of uranium-contaminated organic wastewater.