RESUMO
Two 1,2,3-triazolium ionic liquid diluents were evaluated for the extraction of gallium from spent Bayer process liquor by Kelex® 100. The first of these is a hydrophobic ionic liquid with a low water content, which allows the extraction of gallium directly from untreated Bayer process liquor. The second is based on a hydrophilic ionic liquid and which forms an aqueous biphasic system with concentrated salt solutions. The aqueous biphasic system homogenizes upon cooling, which allows homogeneous liquid-liquid extraction of gallium from carbonated Bayer process liquors. The influence of the ionic liquids on the extraction kinetics, mechanism, thermodynamics and selectivity is investigated. Stripping was examined from both systems and their potential for industrialization is discussed. Ionic liquids are shown to beneficially influence the extraction process from thermodynamic and kinetic perspectives. They are therefore promising to solve the issues which have thus far prevented the industrial application of resource-efficient solvent extraction techniques for the recovery of gallium from spent Bayer process liquor.
RESUMO
The less polar phase of liquid-liquid extraction systems has been studied extensively for improving metal separations; however, the role of the more polar phase has been overlooked for far too long. Herein, we investigate the extraction of metals from a variety of polar solvents and demonstrate that, the influence of polar solvents on metal extraction is so significant that extraction of many metals can be largely tuned, and the metal separations can be significantly enhanced by selecting suitable polar solvents. Furthermore, a mechanism on how the polar solvents affect metal extraction is proposed based on comprehensive characterizations. The method of using suitable polar solvents in liquid-liquid extraction paves a new and versatile way to enhance metal separations.
RESUMO
Novel 1,2,3-triazolium ionic liquids with a high base stability were synthesized for use in solvent extraction of first-row transition elements and rare earths from chloride media. The synthesis of these ionic liquids makes use of a recently reported, metal-free multicomponent reaction that allows full substitution of the 1,2,3-triazolium skeleton. The physical and chemical properties of these ionic liquids are compared with those of a trisubstituted analog. Peralkylation of the 1,2,3-triazolium skeleton leads to ionic liquids with superior properties, such as low viscosity, low solubility in water and higher thermal and base stability. Iodide and thiocyanate ionic liquids with peralkylated cations were applied to the solvent extraction of metal ions, and their stability in alkaline media was exploited in the selective stripping of the metals from the loaded ionic liquid phase by alkaline solutions. EXAFS and Raman spectroscopy were performed to gain insight into the extraction mechanism. The applicability of these extraction systems was demonstrated in separations relevant for the recovery of metals from ores and end-of-life products: Fe(iii)/Cu(ii)/Zn(ii) (copper ores, brass scraps) and Fe(iii)/Nd(iii) (rare earth magnets).
RESUMO
Sulfamic acid (NH3-SO3) is an acidic zwitterion with many applications. N-Alkylated derivatives are introduced, which can be used as a new class of metal extractants R2NH-SO3 and as new super-acidic ionic liquids [R2NH-SO3H][Tf2N]. The synthesis, properties and novel applications of this versatile platform are discussed.
RESUMO
New sulfonic acid functionalized ionic liquids (SAFILs) with bis(trifluoromethylsulfonyl)imide anions were synthesized. These ionic liquids are strong Brønsted acids and can solubilize metal oxides. Water-immiscible SAFILs were used as organic phases in solvent extraction studies.
