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研究了用三烷基氧膦（ＴＲＰＯ）－煤油溶液从硝酸体系中萃取Ｔｃ（Ⅶ）的行为和机理，ＴＲＰＯ萃取Ｔｃ（Ⅶ）的反应式为：Ｈ＋＋ＴｃＯ－４＋２ＴＲＰＯＨＴｃＯ４·２ＴＲＰＯ。给出了ＴＲＰＯ萃取Ｔｃ（Ⅶ）的热力学常数ΔＧｃ、ΔＨｃ、ΔＳｃ以及表观平衡常数Ｋｃ。研究了ＨＮＯ３、ＵＯ２（ＮＯ３）２、Ｚｒ（ＮＯ３）４对ＴＲＰＯ萃取Ｔｃ（Ⅶ）的分配比（Ｄ（Ｔｃ（Ⅶ）））的影响。结果表明：当ｃ（ＨＮＯ３）（ａ）＜０．３５ｍｏｌ／Ｌ时，Ｄ（Ｔｃ（Ⅶ））随着酸度的增加而增加，当ｃ（ＨＮＯ３）（ａ）＞０．３５ｍｏｌ／Ｌ时，Ｄ（Ｔｃ（Ⅶ））随着酸度的增加而降低；Ｔｃ（Ⅶ）分别与ＵＯ２＋２、Ｚｒ４＋存在共萃效应。
The behavior and mechanism of extraction of Tc (Ⅶ) from nitric acid system by trialkylphosphine oxide (TRPO) - kerosene solution were studied. The reaction equation of Tc (Ⅶ) extracted by TRPO was H ++ TcO-4 + 2TRPOHTcO4 · 2TRPO. The thermodynamic constants ΔGc, ΔHc, ΔSc and apparent equilibrium constant Kc of TRP extraction Tc (Ⅶ) are given. The effect of HNO3, UO2 (NO3) 2, Zr (NO3) 4 on the distribution ratio of Tc (Ⅶ) to the TRPO (D (Tc (Ⅶ)) was studied. The results showed that D (Tc (Ⅶ)) increased with the increase of acidity when c (HNO3) (a) <0.35mol / L, D (Tc (Ⅶ)) decreased with the increase of acidity. Tc (Ⅶ) had coextraction with UO2 +2 and Zr4 + respectively.