Organic acid mediated photoelectrochemical reduction of U(VI) to U(IV) in waste water: electrochemical parameters and spectroscopy

The photoelectrochemical reduction of U(VI) is recognized as an economical and effective way to eliminate radioactive pollution. In this study, we construct a α-Fe2O3/TiO2 film electrode-based photoelectrochemical cell to remove U(VI) and recover uranium from aqueous solution. Citric acid and oxalic acid could act as hole scavengers, being favorable for the photocatalytic reduction of U(VI). In the presence of 0.5 mM citric acid and oxalic acid, the uranium removal capacity reached 70% and 58%, respectively, while 24% was achieved for the system in the absence of acid. The XRD, SEM, FT-IR and XPS results revealed that a proportion of U(IV) was also precipitated as surface associated metastudtite. These novel observations have significant implications for the behavior of uranium within engineered and natural environments.