Reductive photo-chemical separation of the hexafluorides of uranium and molybdenum

[Display omitted] •Photochemical UF6 MoF6 separation.•Photochemistry in liquid SO2.•Photochemistry in gaseous, liquid and supercritical CO. Two new techniques are described for the separation of molybdenum hexafluoride (MoF6) from uranium hexafluoride (UF6). Both separation techniques utilize the differences displayed by the hexafluorides in their ability to absorb light in the near UV region. Because UF6 absorbs light in the near UV region and MoF6 does not, this observation was used to selectively reduce UF6 to uranium pentafluoride (UF5) through irradiation with 395 nm light in the presence of a suitable reducing agent. Two reducing agents were chosen for this study: gaseous, liquid, or super-critical carbon monoxide (CO) and liquid sulfur dioxide (SO2). Since MoF6 is not reduced under the reaction conditions described here, it may be removed via distillation from the uranium-containing sample after complete reduction of UF6 to solid UF5. The molybdenum- and uranium-containing samples were measured for purity through elemental analysis using microwave plasma atomic emission spectroscopy (MP-AES). Elemental analysis showed more than 98.8 % of the Mo had been removed from the U-containing samples. Further analyses of the samples were performed by X-ray powder diffraction and IR spectroscopy.