Evidence for the formation of UO2(NO3)42- in an ionic liquid by EXAFS

The complexation between uranium(VI) and nitrate ions in a hydrophobic ionic liquid (IL), namely [BMI][NO3] (BMI = 1-butyl-3-methylimidazolium+), is investigated by EXAFS spectroscopy. It was performed by dissolution of uranyl nitrate UO2(NO3)2·6H2O or UO2(Tf2N)2 (Tf2N = bis(trifluoromethylsulfonyl) imide (CF3SO2)2N−). The formation of the complex UO2(NO3)4 2− is evidenced.