Photo-enhancement Effect on Oxidation Reaction of Uranium (IV) by NO^-_3 in Perchloric Acid Solutions

この論文にアクセスする

この論文をさがす

著者

抄録

Kinetic studies on the oxidation reactions of U(IV) by NO<SUP>-</SUP><SUB>3</SUB> in HClO<SUB>4</SUB> solutions have been carried out spectrophotometrically in the dark and under irradiation with Xe light. Remarkable photo-enhancement effect on the oxidation reaction was observed under the irradiation with UV light below 420nm. This indicates that the photo-enhanced oxidation of U(IV) is not due to the excitation of U(IV) but the excitation of NO-3. It was found that apparent first-order rate constants in both dark (κ<SUB>obs</SUB>) and photo-reactions (κ<SUP>*</SUP><SUB>obs</SUB>) increase with increasing [NO<SUP>-</SUP><SUB>3</SUB>] and approach to constant values. This relation is well correlated with the distribution of nitrato complexes of U(IV). Furthermore, the oxidation rates were found to be independent of [H+](0.5-3.5M(=mol•dm<SUP>-3</SUP>)). From these results, it is proposed that the oxidation of U(IV) by NO<SUP>-</SUP><SUB>3</SUB> proceeds through two paths, i.e., one is the two-electron transfer between U(IV)[U<SUP>4+</SUP> and U(NO<SUB>3</SUB>)<SUP>3+</SUP> species] and NO<SUP>-</SUP><SUB>3</SUB>, and another is the oxygen atom transfer from the coordinated NO<SUP>-</SUP><SUB>3</SUB> to U(IV) in U(NO<SUB>3</SUB>)<SUP>2+</SUP><SUB>2</SUB>. Kinetic parameters are as follows: κ<SUB>obs</SUB>(25°C)=7.0×10<SUP>-6</SUP> s<SUP>-1</SUP>, ΔH<SUP>≠</SUP>=60.8kJ•mol<SUP>-1</SUP>, ΔS<SUP>≠</SUP>=-140J.K<SUP>-1</SUP>.mol<SUP>-1</SUP> and κ<SUP>*</SUP><SUB>obs</SUB>(25°C)=3.0×10<SUP>-5</SUP>s<SUP>-1</SUP>, ΔH<SUP>≠</SUP>=26.3kJ.mol<SUP>-1</SUP>, ΔS<SUP>≠</SUP>=-243J.K<SUP>-1</SUP>.mol<SUP>-1</SUP>.

収録刊行物

  • Journal of nuclear science and technology  

    Journal of nuclear science and technology 34(7), 695-699, 1997-07-25 

    Atomic Energy Society of Japan

参考文献:  20件

参考文献を見るにはログインが必要です。ユーザIDをお持ちでない方は新規登録してください。

各種コード

  • NII論文ID(NAID)
    10002077561
  • NII書誌ID(NCID)
    AA00703720
  • 本文言語コード
    ENG
  • 資料種別
    ART
  • ISSN
    00223131
  • NDL 記事登録ID
    4260278
  • NDL 雑誌分類
    ZM35(科学技術--物理学)
  • NDL 請求記号
    Z53-A460
  • データ提供元
    CJP書誌  NDL  J-STAGE 
ページトップへ