SEPARATION OF EU FROM SM/EU/GD MIXTURE BY PHOTOREDUCTIVE STRIPPING IN SOLVENT-EXTRACTION PROCESS

The photoreductive stripping of Eu from an organic phase (xylene, cyclohexane, or hexane) containing Sm3+, EU(3+), Gd3+, and bis(2-ethylhexyl)phosphoric acid as an extractant has been investigated. The organic phase and an aqueous I M (NH4)(2)SO4 solution were agitated in a glass cell and irradiated with a low-pressure mercury lamp (LPML) or high-pressure mercury lamp (HPML) in the presence of a radical scavenger (isopropyl formate, formic acid, or 2-propanol). The trivalent Eu was photoreduced to the divalent state in the organic phase and precipitated selectively as EuSO4 in the aqueous phase. The effects of organic solvent, radical scavenger, and UV wavelength on the recovery and separation of Eu were studied. The recovery of Eu as EuSO4 from the organic solution initially containing equal amounts (4.5-5 mM) of the three elements reached 93%, and a purity of Eu in the precipitate was about 99% when LPML and 2-propanol were used.