Extraction of Uranium(VI) from Nitric Acid Solution Using Pyrrolidone Derivatives

Abstract

The extraction behavior of uranyl species from HNO₃ aqueous solutions using CH₂ C_l2 containing pyrrolidone derivatives as extractants has been studied to find an alternative to tributyl phosphate as an extractant. In this study, we used N-cyclohexyl-2-pyrrolidone (NCP), N-octyl-2-pyrrolidone (NOP), and N-dodecyl-2-pyrrolidone (NDP) as the extractants. As a result, it was found that NCP, NOP, and NDP (abbreviated as NRP) extract U(VI) as UO₂(NO₃)2(NRP)2, that a part of NCP in CH₂ C_l2 phase is moved to the aqueous phase, and that the extractability (corresponding distribution ratio) of U(VI) increases with increasing [HNO₃]_int from 7% (0.08) ([HNO₃]_int = 0.1 M, [NRP]_int = 1.0 M) to more than 90% (11) ([HNO₃]_int = 3.0 M, [NRP__int = 1.0 M). From these results, it is expected that NOP and NDP extract U(VI) effectively from HNO₃ solution of more than 3M and that the extracted U(VI) species are stripped by using HNO₃ aqueous solution of low concentration.

KEYWORDS:

• amide
• pyrrolidone derivatives
• N-cyclohexyl-2-pyrrolidone
• N-octyl-2-pyrrolidone
• N-dodecyl-2-pyrrolidone
• extraction
• U(VI)