Solubility of Uranyl Nitrate Precipitates with N-Alkyl-2-pyrrolidone Derivatives (Alkyl = n-Propyl, n-Butyl, iso-Butyl, and Cyclohexyl)

Abstract

The solubility of UO2(NO3)2(NRP)2 (NRP = N-alkyl-2-pyrrolidone) in aqueous solutions with HNO3 (0–5.0 M) and the corresponding NRP (0–0.50M) has been studied. As a result, the solubility of each speciesof UO2(NO3)2(NRP)2 generally decreases with increasing concentrations of HNO3 and the corresponding NRP (C HNO3 and C NRP, respectively) in the supernatant. The solubility of UO2(NO3)2(NRP)2 also depends on the type of NRP; a higher hydrophobicity of NRP generally leads to a lower solubility of UO2(NO3)2(NRP)2. The logarithms of effective solubility products (K eff) of UO2(NO3)2(NProP)2, UO2(NO3)2(NBP)2, UO2(NO3)2(NiBP)2, and UO2(NO3)2(NCP)2 at different CHNO3 values and 293K were evaluated. For instance, at CHNO3 = 3:0 M, logK NProP eff = −1:07 ± 0:03, log K NBP eff = −2:23 ± 0:02, log K NiBP eff = −2:59 ± 0:03, and log K NCP eff = −3:80 ± 0:05. The solubility of UO2(NO3)2(NRP)2 is determined by the balance among the common-ligand effect, ionic strength, and variation of log K eff with C HNO3.