Extraction of Np and NpO22+ from Nitric Acid Medium Using TODGA in Room Temperature Ionic Liquids

Extraction of Np and NpO22+ was carried out from nitric acid feeds using solutions of N,N,N′,N′-tetra-n-octyldiglycolamide (TODGA) in two imidazolium-based room temperature ionic liquids, viz., 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide ([Cmim][NTf]) and 1-octyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide ([Cmim][NTf]). The extraction equilibrium was attained within 2 h for both the metal ions in both the ionic liquids. While a cation exchange mechanism is proposed for the extraction of NpO22+, an ion-pair mechanism of extraction is proposed for the Np ion. The nature of the extracted species was determined by carrying out experiments at varying concentrations of TODGA, and species of the type Np(L)(NO) and NpO(L) were found to be extracted in 3 mol·dm HNO. The identification of these extracted species was also supported from the variable nitrate and Cmim ion concentration experiments.