Extraction Behavior and Separation of Precious and Base Metals from Chloride, Bromide, and Iodide Media Using Undiluted Halide Ionic Liquids

Abstract

Within the framework of metal separations and solvent extraction, chloride media are among the most studied systems. Bromide and iodide media have received much less attention, but can allow a different selectivity during the extraction. In present research, the extraction behavior of several precious and base metal ions, i.e. Pt(IV), Pd(II), Rh(III), Au(III), Cu(II), Fe(III) and Ni(II), from the different halide media was explored using the undiluted ionic liquid Aliquat 336 chloride and its bromide and iodide analogues. A single-step separation of Pt(IV) and Pd(II) from Fe(III) and Ni(II) was possible in the iodide system, but it was found to be incompatible with Au(III) and Cu(II). The chloride and bromide media showed potential for the separation of Au(III), Pd(II), Fe(III) and Cu(II), and their performance was subsequently compared. Fe(III) and Cu(II) were easily separated from Au(III) and Pd(II) via an extraction at low acid concentration followed by scrubbing with water for both systems. However, the stripping showed superior characteristics for the bromide system, where Pd(II) could be recovered using a 0.2 mol L -1 ammonia solution and Au(III) using 1.0 mol L -1 sodium sulfite. The proposed method for the separation of Au(III), Pd(II), Fe(III) and Cu(II) can be relevant for the recycling of waste electric and electronic equipment or analytical applications. The results highlight the importance of considering halides other than chloride as both the extraction and stripping properties of the system can be changed.

Non-equilibrium solvent extraction in milliflow reactors: Precious and base metal separations with undiluted ionic liquids

“…In line with previous work, experiments have been performed using undiluted ionic liquids and chloride and bromide feed solutions. [53] To the best of our knowledge, this is the first report of the use of the undiluted ionic liquid Aliquat 336 in a milli-or microfluidic contactor. The research involves a study of different parameters influencing the non-equilibrium metal separations.…”

Amide-functionalised phosphonium-based ionic liquids as ligands for rhodium(iii) extraction

“…Solvent extraction of Rh(III) has been studied using various kind of ligands, such as di-n-hexylsulde (DHS), 23 tri-n-butylphosphate (TBP), 24 aliphatic tertiary amines (e.g., Alamine 336), 24 and quaternary ammonium salts (e.g., Aliquat 336). 25 However, there have been few reports on quantitative extraction of Rh(III), 26 and there are no commercially available extractants that have suitable extractability and selectivity for Rh(III). [27][28][29] Hence, there is a need for more effective Rh extractants.…”

Recent Studies on Ionic Liquids in Metal Recovery from E-Waste and Secondary Sources by Liquid-Liquid Extraction and Electrodeposition: a Review

“…Therefore, it has been observed that, when ILs are used as extractants, diluents are also used along with ILs to solve the problem of high viscosity (Dhiman and Gupta 2020). Sometimes ILs with low viscosity are used to solve the problem of high viscosity and sometimes a mixture of two ILs can be used to reduce the viscosity, but their mixture may not show a synergistic effect and have a negative effect on the extraction efficiency (Łukomska et al 2020a, b;Micheau et al 2020;Vereycken et al 2020).…”