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It is necessary to recover precious metals from aqueous solutions because they have a wide range of applications. In this work, a poly(ionic liquid) (PIL) gel containing an imidazole group was fabricated using a radiation method and utilized for the capture of Au(III), Pt(IV), and Pd(II) ions. It was discovered that the PIL gel exhibited high adsorption efficiency for Au(III), Pt(IV), and Pd(II) in a wide pH range. The adsorption processes for target ions all reached equilibrium within 4 min. Meanwhile, the isotherm experiments revealed that the adsorption was in accordance with the Langmuir model, and the maximum adsorption capacities were 854.7 mg g−1 for Au(III), 420.2 mg g−1 for Pt(IV), and 277.8 mg g−1 for Pd(II). Furthermore, the PIL gel could selectively adsorb Au(III), Pt(IV), and Pd(II) from simulated acidic waste effluent containing Cu(II), Zn(II), Fe(III), and Ni(II). In particular, the PIL gel demonstrated its ability to selectively recover trace Au(III) from real gold slag leaching solution. FTIR and XPS analyses revealed that anion exchange was the dominant adsorption mechanism. [ABSTRACT FROM AUTHOR]

1-Methylimidazole (1-MIM) and 2-methylimidazole (2-MIM) are miscible in water and imidazolium based ionic liquids (ILs), and can coordinate with soft metal ions. This paper reports a novel solvent extraction process for trivalent lanthanides and yttrium from aqueous solutions into ILs, which was promoted by a hydrophilic 1-MIM or 2-MIM. Slope analysis confirmed that MIM in ILs formed a 1 : 1 complex with La3+ and Y3+ and a 1 : 4 complex with Eu3+ and Lu3+, depending on the atomic number of the metal and the metal-ligand interactions that have been characterized by FTIR spectroscopy and ESI-MS. The effect of nitrate concentration on the extraction of lanthanides with 1-MIM in ILs was analysed. It indicated that nitrate anions were involved in the extraction process. Under the same conditions, the extraction of lanthanides with MIM into n-pentanol was carried out. The extractability was by far lower than that obtained in ILs. Both cationic exchange and neutral solvation mechanisms occurred in ILs and only the neutral solvation mechanism occurred in n-pentanol, which were demonstrated by the extraction tests and the structure of extracted species determined by ESI-MS. The competitive extraction in ILs showed good selectivity for lanthanides compared to alkali metals and alkaline earth cations. After extraction, lanthanides could be stripped very easily from the ionic liquid phase with dilute nitric acid. From the temperature dependence data, the thermodynamic parameter values (ΔH, ΔS and ΔG) were calculated. The results indicated that the extraction reactions were spontaneous and went through an endothermic process. [ABSTRACT FROM AUTHOR]

The synthesis of a novel poly(ionic liquid) adsorbent (PIL-APIBCl) through the modification of poly(styrene-co-maleic anhydride) (PSMA) composites with N-(3-aminopropyl)imidazole (API) and benzyl chloride (BCl) is presented. The structural analysis was carried out by nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FT-IR). Batch adsorption experiments revealed that the investigated adsorbent exhibited good selectivity and a high adsorption capacity of 236.68 mg g−1 towards tetrachloroaurate (Au(III)) ions at pH 1.0 over a wide temperature range. The adsorption isotherms and kinetics of Au(III) on the PIL-APIBCl were fitted well by the Langmuir isotherm model and pseudo-second-order model, respectively, indicating successful chemical adsorption of Au(III) ions on the adsorbent surfaces. According to FESEM, FT-IR, XPS and NMR analysis, the adsorption mechanisms of Au(III) on PIL-APIBCl could be ascribed to electrostatic and intermolecular interactions. Therefore, due to its good cyclability and low cost, PIL-APIBCl is a promising adsorbent for Au(III) recovery from wastewater on a large scale. [ABSTRACT FROM AUTHOR]

An air stable, water soluble, and efficient ionic liquid-tagged Schiff base palladium complex was prepared. The synthesized complex was well characterized by NMR, mass spectrometry, FT-IR, UV-visible spectroscopy and powder X-ray diffraction. The complex was used as a catalyst for the Suzuki and Heck cross-coupling reactions in water. Good to excellent yields were achieved using a modest amount of the catalyst. In addition, the catalyst can be easily reused and recycled for six steps without much loss in activity, exhibiting an example of sustainable and green methodology. [ABSTRACT FROM AUTHOR]

In the last decade, aqueous two-phase systems (ATPS) composed of ionic liquids (ILs) and inorganic salts have been largely explored as novel extractive platforms. The use of ILs as phase-forming components in ATPS has led to outstanding extraction performances compared to more traditional approaches. Nevertheless, despite those exceptional achievements, IL regeneration, recycling and reuse lagged behind and still remain a challenging task towards the development of greener cost-effective processes. Aiming at overcoming these shortcomings, the phase diagrams of novel ATPS composed of imidazolium-based ILs and Na2CO3 or Na2SO4 were determined and their extraction efficiencies for a model antioxidant - gallic acid - were evaluated. The most promising IL-based ATPS were then used in sequential two-step cycles (product extraction/IL recovery) so as to evaluate the efficacy on the IL recyclability and reusability. Extraction efficiency values ranging between 73% and 99% were obtained in four sequential partitioning experiments involving gallic acid while allowing the regeneration of 94-95% of the IL and further reutilization. Moreover, to support the vast applicability of the back-extraction routes and the recyclability concept proposed here, the most prominent systems were further tested with two additional antioxidants, namely syringic and vanillic acids. In both examples, the extraction efficiencies were higher than 97%. The remarkable results obtained in this work support the establishment of IL-based ATPS as a sound basis of greener cost-effective strategies with a substantial reduction in the environmental footprint and economical issues. [ABSTRACT FROM AUTHOR]

A water-stable ionic liquid, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [C4mim][CF3SO3], is herein proposed to be used in the formation of aqueous biphasic systems (ABS) with a large range of mono- and disaccharides, as well as polyols. Binodal curves, tie-lines, and densities and viscosities of the co-existing aqueous phases, were determined for each ternary system. The proposed systems are low-viscous offering enhanced features over conventional polymer-based ABS. In addition, the partitioning of model biomolecules, such as l-tryptophan, caffeine, and β-carotene, was further investigated to ascertain the applicability of such ABS. These systems are particularly interesting in the recovery of bioactive products from natural sources, while the availability of carbon-based sources to cells constitutes a major advantage in separations from fermentative media. Moreover, the use of carbohydrates in ionic-liquid-based ABS constitutes a step forward along the biorefinery concept envisaging sustainable conversions of biomass into a broad spectrum of bio-based products. [ABSTRACT FROM AUTHOR]