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Hydrophobic phosphonium-based ionic liquids as novel extractants for palladium(II) recovery from alkaline cyanide solutions
- Source :
- Journal of Molecular Liquids. 336:116358
- Publication Year :
- 2021
- Publisher :
- Elsevier BV, 2021.
-
Abstract
- Although phosphonium-based ionic liquids (ILs) have become popular green solvents for the separation of precious metals, these solvents have not been used thus far to recover Pd(II) from alkaline cyanide solutions. In this study, three novel phosphonium-based ILs, viz. tributyl(2-ethylhexyl) phosphonium bromide (TBEHPB), trioctyl (2-ethylhexyl) phosphonium bromide (TOEHPB), and trioctyl undecyl phosphonium bromide (TOUPB), were synthesized, respectively, and these ILs were used for the recovery of Pd(CN)42− for the first time. With the increase in the length of the alkyl chain in the phosphonium cation, the extraction percentage of Pd(II) increased. Under optimum conditions (i.e., contact time of 5 min, pH of 10.5, and temperature of 298 K), the TOUPB system exhibited a Pd(II) extraction percentage of greater than 99.0%. Furthermore, the TOUPB system exhibited excellent selectivity for Pd(II) in a mixed solution (separation factors of βPd/Fe and βPd/Co were greater than 2.0 × 103). The Pd(II) recovery percentage was still greater than 90.0% after five consecutive extraction-stripping cycles. The Job’s method, infrared spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy, and UV–vis spectroscopy revealed that the extraction mechanism is ion exchange. The supramolecular structure of the extraction complex was established on the basis of density functional theory (DFT) calculations and Karl Fischer titration, and the extraction mechanism was further described at the molecular structure level. This study provides a new process for recovering Pd(II) from an alkaline cyanide medium.
- Subjects :
- Ion exchange
Cyanide
Extraction (chemistry)
Infrared spectroscopy
chemistry.chemical_element
02 engineering and technology
010402 general chemistry
021001 nanoscience & nanotechnology
Condensed Matter Physics
01 natural sciences
Atomic and Molecular Physics, and Optics
0104 chemical sciences
Electronic, Optical and Magnetic Materials
chemistry.chemical_compound
chemistry
Bromide
Ionic liquid
Materials Chemistry
Phosphonium
Physical and Theoretical Chemistry
0210 nano-technology
Spectroscopy
Nuclear chemistry
Palladium
Subjects
Details
- ISSN :
- 01677322
- Volume :
- 336
- Database :
- OpenAIRE
- Journal :
- Journal of Molecular Liquids
- Accession number :
- edsair.doi...........0169ad14d2463795755bc352a59ffc53