検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年

Reduction behavior of uranium in the presence of citric acid

クエン酸存在下におけるウランの還元挙動

鈴木 義規; 南川 卓也; 吉田 崇弘*; 尾崎 卓郎; 大貫 敏彦; Francis, A. J.; 津島 悟*; 榎田 洋一*; 山本 一良*

Suzuki, Yoshinori; Nankawa, Takuya; Yoshida, Takahiro*; Ozaki, Takuo; Onuki, Toshihiko; Francis, A. J.; Tsushima, Satoru*; Enokida, Yoichi*; Yamamoto, Ichiro*

クエン酸存在下、pH2-7におけるUO$$_{2}$$$$^{2+}$$の還元挙動をカラム電極電解法を用いて調べた。UO$$_{2}$$$$^{2+}$$は、pH2で1段階の還元反応により、pH3-5で2段階の還元反応によりU(IV)まで還元された。UO$$_{2}$$$$^{2+}$$の還元電位は、pHが2から7に増加するのにしたがって低電位にシフトした。pH6-7では、-0.8V以下の電位でもUO$$_{2}$$$$^{2+}$$は完全に還元されなかった。紫外可視吸収スペクトル分析及び化学種計算から、クエン酸存在下におけるUO$$_{2}$$$$^{2+}$$の化学種は、pH2-3ではおもにUO$$_{2}$$$$^{2+}$$, pH3-5でおもに[(UO$$_{2}$$)$$_{2}$$Cit$$_{2}$$]$$^{2-}$$, pH5-7では3量体以上の化学種であった。これらの結果から、UO$$_{2}$$$$^{2+}$$は中性pH付近でクエン酸と多量体を形成し、還元されにくくなることがわかった。

We examined the reduction behavior of UO$$_{2}$$$$^{2+}$$ in citrate media at pH 2.0-7.0 by column electrodes. At pH 2.0, UO$$_{2}$$$$^{2+}$$ was reduced to U(IV) through a one-step reduction process, while it was reduced to U(IV) through a two-step reduction process at pH 3.0-5.0. The reduction potential of UO$$_{2}$$$$^{2+}$$ shifted to lower values with an increase in pH from 2.0 to 7.0. At pH 6.0 and 7.0, UO$$_{2}$$$$^{2+}$$ was not reduced to U(IV) completely at the electrode potential above -0.8 V. Ultraviolet-visible spectroscopy and speciation calculation of UO$$_{2}$$$$^{2+}$$ in citrate media indicated that uranium existed as a mainly UO$$_{2}$$$$^{2+}$$ at pH 2-3, and a predominant species at pH 3-5 was [(UO$$_{2}$$)$$_{2}$$Cit$$_{2}$$]$$^{2-}$$. At pH 5-7, polymeric complexes were present. These findings suggest that the reduction of UO$$_{2}$$$$^{2+}$$ is more difficult by polymerization of UO$$_{2}$$$$^{2+}$$ with citric acid at higher pHs.

Access

:

- Accesses

InCites™

:

パーセンタイル:22.32

分野:Chemistry, Inorganic & Nuclear

Altmetrics

:

[CLARIVATE ANALYTICS], [WEB OF SCIENCE], [HIGHLY CITED PAPER & CUP LOGO] and [HOT PAPER & FIRE LOGO] are trademarks of Clarivate Analytics, and/or its affiliated company or companies, and used herein by permission and/or license.