Tantalum and Niobium Selective Extraction by Alkyl-Acetophenone

A study has been carried out on Ta and Nb recovery by a liquid-liquid extraction process using 4-methylacetophenone (4-MAcPh) as the organic phase. The 4-MAcPh was compared to methyl isobutyl ketone (MIBK) with respect to extraction efficiencies (D values) at different concentrations of H2SO4 in the aqueous phase. The results showed a similar extraction of Nb for both solvents. However, for Ta, extraction efficiency is increased by a factor of 1.3 for 4-MAcPh. In addition, the MIBK solubilized completely after 6 mol∙L−1 of H2SO4 against only a loss of 0.14–4% for 4-MAcPh between 6 and 9 mol∙L−1 of H2SO4. The potential of 4-MAcPh has also been studied to selectively recover Ta from a model capacitor waste solution. The results showed a selectivity for Ta in the presence of impurities such as Ag, Fe, Ni and Mn. The 4-MAcPh also presents the advantage of having physicochemical properties adapted to its use in liquid-liquid extraction technologies such as mixer-settlers

Toward a method of understanding the complexation of rare earth element by functionalized organosilanes in aqueous media

International audienc

Organic chemistry under hydrothermal conditions

At elevated temp., several properties of water are strongly altered compared to what our daily experience tells us: the dielec. const. of water, for example, is reduced, so that water can more easily solubilize org. mols. In addn., the self-dissocn. const. of water is increased (by three orders of magnitude at 250 °C), thus favoring H+- and OH--catalyzed reactions. Surprisingly, while room-temp. water and supercrit. water (SCW) are well known for promoting org. reactions, the middle temp. range still remains largely unexplored. Therefore, this contribution aims at giving an overview of org. reactions that may be promoted by superheated water

PalmitateLuciferin: A Molecular Design for the Second Harmonic Generation Study of Ion Complexation at the Air–Water Interface

A molecular organic chromophore, PalmitateLuciferin, has been synthesized for studying ion complexation at the air–water interface using second harmonic generation (SHG). This molecule was designed through the addition of a long hydrophobic palmitoyl alkyl chain to the aromatic π-electron system of Luciferin. We first demonstrate that this organic chromophore is a potential candidate for SHG studies of ion complexation with the measurement of its first hyperpolarizability in aqueous solutions by hyper Rayleigh scattering (HRS) with and without calcium ions. Then, we characterize the PalmitateLuciferin surfactant properties at the air–water interface combining surface tension measurements with a surface SHG study and Brewster angle imaging. These results allow us to build a molecular description of the chromophore at the interface and observe its molecular reorganization during the monolayer compression leading to the formation of aggregates. Finally, we show that the initial goal of the designing work is achieved since PalmitateLuciferin indeed exhibits a higher SHG response in the presence of calcium ions in the aqueous subphase as expected