Extraction of Np(Ⅳ) From Nitric Acid Solution With Di(1-Methyl-Heptyl) Methyl Phosphonate

The extraction of Np(Ⅳ) from nitric acid medium by using di(1-methyl-heptyl) methyl phosphonate diluted in kerosene was investigated. The influences were studied in this research including the contact time, the concentration of DMHMP, HNO₃ as well as nitrate and the temperature. Slope analyses indicate that Np(Ⅳ) is coordinated mainly in the form of neutral molecules and the extractant complex is Np(NO₃)₄·2DMHMP. The value of enthalpy change for the reaction is negative which means that the extraction of Np(Ⅳ) is an exothermic process.