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Photoreduction of uranyl(VI) ion (UO22+) in acid solutions has been studied with a steady-state and time-resolved exciting light, where methanol (MeOH), ethanol (EtOH) and iso-propanol (iso-PrOH) were used as quenchers (RCH2OH) and HClO4, H2SO4 and H3PO4 as acid solvents (S). The quantum yields, φ(U4+) of resultant U4+ and the rate constants, kq, for the quenching of excited UO22+ ( ∗ UO 2 2+ ) by RCH2OH were determined. The kq values increased in the order of MeOH, EtOH and iso-PrOH corresponding to the increase of φ(U4+) at [RCH2OH] up to 1.0 mol dm−3, while at the higher [RCH2OH] the φ(U4+) reached the same maximum less than unity regardless of the kinds of RCH2OH. The photoreduction with 1.5 mol EtOH dm−3 in the acid solutions showed that the φ(U4+) increased in the order of HClO4, H2SO4 and H3PO4 in the whole range of [S]. |
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