Separation of Precious Metals by Using Undiluted Ionic Liquids

Abstract

The ionic liquid (IL), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][Tf 2 N]), was evaluated as an extractant without dilution for the separation and recovery of precious metals. Au(III) was efficiently extracted from the aqueous phase to the IL phase, and a concentrated Au(III) solution almost 8 times higher than the initial feed solutions could be produced. In contrast, Pd(II) was rarely extracted and Pt(IV) was partly extracted under the present experimental conditions. Furthermore, the effect of the IL anions on the extraction ability for the metal ions was examined, and it was found that an IL having an anion component slightly more hydrophilic compared to shown that ILs could be effective extractants for the separation of precious metals.

Extraction and Separation of Pt and Pd by an Imidazolium-Based Ionic Liquid Combined with Phosphonium Chloride

“…An imidazolium based ionic liquid, [C 8 mim][Tf 2 N] has been reported to have an extractive selectivity for Pt(IV) in a previous publication [19]. As shown in Figure 2 …”

“…Commercial extractants such as crown ethers and octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and newly synthesized extractants have been used to extract cationic metal ions [10,12]. Furthermore, ILs have been used for extraction both dissolved in organic solvents [13][14][15] and as an undiluted extraction phase [16][17][18][19][20][21][22]. Phosphonium based ILs such as trihexyltetradecylphosphonium chloride, bromide and phosphinate have been applied to the separation of PGMs [21,22].…”

“…Phosphonium based ILs such as trihexyltetradecylphosphonium chloride, bromide and phosphinate have been applied to the separation of PGMs [21,22]. Recently, undiluted imidazolium based ILs have been reported to have a high extraction ability for Au(III) and Pt(IV), as well as the ability to separate these metals from Pd(II) [16,19,20]. Two different ILs [C 8 mim][Tf 2 N] and a phosphonium-based IL, [P 6,6,6,14 ][Br], have been applied to a two-step extraction and separation of Pt(IV) and Pd(II) [21].…”

Separation and Recycling for Rare Earth Elements by Homogeneous Liquid-Liquid Extraction (HoLLE) Using a pH-Responsive Fluorine-Based Surfactant

“…In addition to this process, various separating agents and methods for metal separation have also been recently developed. These include solvent extraction using ionic liquids [1,2], phase separation extraction using stimuli-responsive polymers [3][4][5][6], and solid-phase extraction using the adsorption effect of biological materials [7][8][9]. Among these, it is especially noteworthy that in 1988, Igarashi and Yotsuyanagi discovered the pH-dependent phase separation phenomenon, resulting from the addition of acid to a perfluorooctanoic acid (PFOA) aqueous solution containing trace amounts of acetone [10].…”

Metal-selective Deprotection-mediated Palladium(II) Extraction by Ionic Liquids with Tetrahydropyran-2H-yl-protected Thiol Moieties

“…27 Since DHS is a practically applied extractant for palladium extraction in organic solvent systems, 13 ¹ ] IL phase (0.50 mL) from an aqueous phase (2.0 mL) were carried out by mixing in a vial tube followed by vigorous shaking at 1250 rpm for 30 min. The resulting mixture was centrifuged to make a two-phase separated state between the IL phase and the aqueous phase.…”