The unusual extraction behavior of americium(III) and dioxouranium(VI) from picric acid medium using neutral oxodonors II. A thermodynamic study

Abstract

The role of temperature on the distribution of Am 3+ and UO22+ was investigated in the extraction systems involving TBP and DOSO as the neutral oxodonors and picrate as the organophilic counter anion. The inner-sphere water molecules and their substitution by the oxodonor molecules appeared to influence the extraction constants of these metal ions. The conditional extraction constants for Am 3+ were found to be larger (about 3 order of magnitude) than those for UO22+. From the thermodynamics data it appeared that both TBP as well as DOSO bind Am 3+ ion through outer-sphere coordination. In presence of IM NaC1, though the interaction with TBP remains unaltered DOSO tend to form an inner-sphere complex. On the other hand, UQ2 2+ forms inner-sphere complexes with DOSO and outer-sphere complex with TBP in the absence of salt. In the presence of IM NaC1, both TBP and DOSO form inner-sphere complexes. The effect of ionic strength on metal ion extraction was also investigated.

Base Metal Ion Extraction and Stripping from WEEE Leachate by Liquid-liquid Extraction

“…25 However, TBP due to being an "outer sphere" ligand, is unable to expulse inner water molecules of metal-ligand complex and hence complexation termination causes low extractability of TBP. 26 Figure 9 shows the effect of sulphuric acid on metal stripping from the organic phase. Since sulphuric acid, a strong acid, is capable of losing a proton (H + ) and being ionised (dissociated) in the stripping phase more than other mineral acids, the highest stripping percentage was obtained between 1.0 M and 1.5 M of H 2 SO 4 .…”