甲基膦酸二甲庚酯对硝酸介质中Pu(Ⅳ)的萃取

Extraction of Pu(Ⅳ) in Nitric Acid Medium With Di(1-Methyl-Heptyl)Methyl Phosphonate

摘要: 研究了 HNO3介质中甲基膦酸二甲庚酯(DMHMP) 对Pu(Ⅳ)的萃取性能，考察了DMHMP浓度、NO-3浓度、HNO3浓度以及温度对Pu(Ⅳ)分配比的影响。确定了DMHMP萃取Pu(Ⅳ)的萃合物的组成为Pu(NO₃)₄·2DMHMP，其萃取反应方程式为：
Pu⁴⁺_(a)+2DMHMP_(o)+4NO^-_3(a) Pu(NO₃)₄·2DMHMP_(o)
其中Pu(Ⅳ)与NO^-₃形成中性分子，再与DMHMP结合成为中性配合物进入有机相。在实验范围内Pu(Ⅳ)分配比与DMHMP浓度的平方、NO^-₃浓度的四次方成正比，萃取过程为放热反应，反应的焓变为-34.46 kJ/mol。

Abstract: The extraction behavior of Pu(Ⅳ) in HNO₃medium with di(1-methyl-heptyl) methyl phosphonate(DMHMP) was studied. The effects of DMHMP concentration, NO^-₃ concentration, HNO₃ concentration and temperature on Pu(Ⅳ) distribution ratio were investigated. The complex formation of Pu(Ⅳ) with DMHMP is Pu(NO₃)₄·2DMHMP and the extraction reaction equation is determined as follows:
Pu⁴⁺_(a)+2DMHMP_(o)+4NO^-_3(a) Pu(NO₃)₄·2DMHMP_(o)
Pu(Ⅳ) is formed neutral molecules with NO^-₃, which then combine with DMHMP to form a neutral complex and enter the organic phase. Pu(Ⅳ) distribution ratio is proportional to the square of DMHMP concentration and the fourth power of NO^-₃ concentration. The extraction reaction is exothermic, and the enthalpy of the reaction is -34.46 kJ/mol.