Molecules

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11 pages, 2891 KiB

Open AccessArticle

Utilizing Recyclable Task-Specific Ionic Liquid for Selective Leaching and Refining of Scandium from Bauxite Residue

by Eleni Mikeli, Efthimios Balomenos and Dimitrios Panias

Molecules 2021, 26(4), 818; https://doi.org/10.3390/molecules26040818 - 4 Feb 2021

Cited by 5 | Viewed by 2417

Ionic liquids (ILs) have attracted great interest in the field of extractive metallurgy mainly because they can be utilized in low temperature leaching processes where they exhibit selectivity and recyclability. A major drawback in mixed aqueous-IL systems, is IL dissolution in the aqueous [...] Read more.

Ionic liquids (ILs) have attracted great interest in the field of extractive metallurgy mainly because they can be utilized in low temperature leaching processes where they exhibit selectivity and recyclability. A major drawback in mixed aqueous-IL systems, is IL dissolution in the aqueous phase, which leads to IL losses, increasing the overall processing cost. This study advances the method for recovering scandium (Sc) from bauxite residue (BR) using as leaching agent the IL betainium bistriflimide, [Hbet][Tf₂N] mixed with water, which has been reported in previous publications. Ionic liquid leachate (IL-PLS) was prepared by leaching BR with a mixture of [Hbet][Tf₂N]-H₂O and subjected to different stripping experiments using hydrochloric acid. The advancement, presented in this work, is related with the optimization of the metal extraction (stripping) from the IL-PLS, where an aqueous solution with high Sc concentration and minimum metal impurities and minimum IL co-extraction is produced. It is further proven that the metal cation extraction is defined by the stoichiometry of the acidic solution and the dissolution (losses) of the IL in the aqueous phase can be minimized by adjusting the volume ratio and the acid concentration. A two-step stripping process described, achieves the selective increase of Sc concentration by 8 times in the aqueous solution, while maintaining cumulative IL losses to similar levels as the optimum 1 step non-Sc selective stripping process. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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13 pages, 1303 KiB

Open AccessFeature PaperArticle

Efficient Low-Cost Procedure for Microextraction of Estrogen from Environmental Water Using Magnetic Ionic Liquids

by Paula Berton, Noureen Siraj, Susmita Das, Sergio de Rooy, Rodolfo G. Wuilloud and Isiah M. Warner

Molecules 2021, 26(1), 32; https://doi.org/10.3390/molecules26010032 - 23 Dec 2020

Cited by 14 | Viewed by 3437

Abstract

In this study, three magnetic ionic liquids (MILs) were investigated for extraction of four estrogens, i.e., estrone (E1), estradiol (E2), estriol (E3), and ethinylestradiol (EE2), from environmental water. The cation trihexyl(tetradecyl)phosphonium ([P₆₆₆₁₄]⁺), selected to confer hydrophobicity to the resulting [...] Read more.

In this study, three magnetic ionic liquids (MILs) were investigated for extraction of four estrogens, i.e., estrone (E1), estradiol (E2), estriol (E3), and ethinylestradiol (EE2), from environmental water. The cation trihexyl(tetradecyl)phosphonium ([P₆₆₆₁₄]⁺), selected to confer hydrophobicity to the resulting MIL, was combined with tetrachloroferrate(III), ferricyanide, and dysprosium thiocyanate to yield ([P₆₆₆₁₄][FeCl₄]), ([P₆₆₆₁₄]₃[Fe(CN)₆]), and ([P₆₆₆₁₄]₅[Dy(SCN)₈]), respectively. After evaluation of various strategies to develop a liquid–liquid microextraction technique based on synthesized MILs, we placed the MILs onto a magnetic stir bar and used them as extracting solvents. After extraction, the MIL-enriched phase was dissolved in methanol and injected into an HPLC–UV for qualitative and quantitative analysis. An experimental design was used to simultaneously evaluate the effect of select variables and optimization of extraction conditions to maximize the recovery of the analytes. Under optimum conditions, limits of detection were in the range of 0.2 (for E3 and E2) and 0.5 μg L⁻¹ (for E1), and calibration curves exhibited linearity in the range of 1–1000 μg L⁻¹ with correlation coefficients higher than 0.998. The percent relative standard deviation (RSD) was below 5.0%. Finally, this method was used to determine concentration of estrogens in real lake and sewage water samples. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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14 pages, 4090 KiB

Open AccessArticle

Quaternary Ammonium-Based Ionosilica Hydrogels as Draw Solutes in Forward Osmosis

by Alysson Duarte Rodrigues, Matthieu Jacob, Véronique Gauchou, Jean-Olivier Durand, Philippe Trens and Peter Hesemann

Molecules 2020, 25(24), 5987; https://doi.org/10.3390/molecules25245987 - 17 Dec 2020

Cited by 2 | Viewed by 2718

Abstract

In the last few years, forward osmosis (FO) has attracted increasing interest as a sustainable technique for water desalination and wastewater treatment. However, FO remains as an immature process principally due to the lack of efficient and easily recyclable draw solutes. In this [...] Read more.

In the last few years, forward osmosis (FO) has attracted increasing interest as a sustainable technique for water desalination and wastewater treatment. However, FO remains as an immature process principally due to the lack of efficient and easily recyclable draw solutes. In this work, we report that ionosilica hydrogels based on quaternary ammonium halide ionosilica are efficient draw solutes in FO. Fluidic ionosilica hydrogels were obtained via hydrolysis-polycondensation reactions of a trisilylated quaternary ammonium precursor in slightly acidic water/ethanol solvent mixtures. The liquid-to-gel transition of the precursor and the kinetics of the formation of hydrogels were monitored by liquid NMR measurements. The formed hydrogels were shown to generate osmotic pressure up to 10.0 atm, indicating the potential of these hydrogels as efficient draw solutes in FO. Our results suggest that iodide anions are the osmotically active species in the system. Regeneration of the hydrogels via ultrafiltration (UF) was successfully achieved, allowing the development of a closed FO-UF process. However, the osmotic performances of the ionosilica hydrogels irreversibly decreased along the successive FO-UF cycles, probably due to anion exchange processes. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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18 pages, 3848 KiB

Open AccessFeature PaperArticle

Integrated Leaching and Separation of Metals Using Mixtures of Organic Acids and Ionic Liquids

by Silvia J. R. Vargas, Helena Passos, Nicolas Schaeffer and João A. P. Coutinho

Molecules 2020, 25(23), 5570; https://doi.org/10.3390/molecules25235570 - 27 Nov 2020

Cited by 8 | Viewed by 4165

Abstract

In this work, the aqueous phase diagram for the mixture of the hydrophilic tributyltetradecyl phosphonium ([P₄₄₄₁₄]Cl) ionic liquid with acetic acid (CH₃COOH) is determined, and the temperature dependency of the biphasic region established. Molecular dynamic simulations of the [P [...] Read more.

In this work, the aqueous phase diagram for the mixture of the hydrophilic tributyltetradecyl phosphonium ([P₄₄₄₁₄]Cl) ionic liquid with acetic acid (CH₃COOH) is determined, and the temperature dependency of the biphasic region established. Molecular dynamic simulations of the [P₄₄₄₁₄]Cl + CH₃COOH + H₂O system indicate that the occurrence of a closed “type 0” biphasic regime is due to a “washing-out” phenomenon upon addition of water, resulting in solvophobic segregation of the [P₄₄₄₁₄]Cl. The solubility of various metal oxides in the anhydrous [P₄₄₄₁₄]Cl + CH₃COOH system was determined, with the system presenting a good selectivity for CoO. Integration of the separation step was demonstrated through the addition of water, yielding a biphasic regime. Finally, the [P₄₄₄₁₄]Cl + CH₃COOH system was applied to the treatment of real waste, NiMH battery black mass, being shown that it allows an efficient separation of Co(II) from Ni(II), Fe(III) and the lanthanides in a single leaching and separation step. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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11 pages, 762 KiB

Open AccessArticle

Liquid-Liquid Extraction of Indium(III) from the HCl Medium by Ionic Liquid A327H⁺Cl⁻ and Its Use in a Supported Liquid Membrane System

by Francisco José Alguacil

Molecules 2020, 25(22), 5238; https://doi.org/10.3390/molecules25225238 - 10 Nov 2020

Cited by 10 | Viewed by 2474

Abstract

Ionic liquid A327H⁺Cl⁻ was generated by reaction of tertiary amine A327 and HCl, and the liquid-liquid extraction of indium(III) from the HCl medium by this ionic liquid dissolved in Solvesso 100 was investigated. The extraction reaction is exothermic. The numerical [...] Read more.

Ionic liquid A327H⁺Cl⁻ was generated by reaction of tertiary amine A327 and HCl, and the liquid-liquid extraction of indium(III) from the HCl medium by this ionic liquid dissolved in Solvesso 100 was investigated. The extraction reaction is exothermic. The numerical analysis of indium distribution data suggests the formation of A327H⁺InCl₄⁻ in the organic phase. The results derived from indium(III) extraction have been implemented in a supported liquid membrane system. The influence of the stirring speed (600–1200 min⁻¹), carrier concentration (2.5–20% v/v) in the membrane phase, and indium concentration (0.01–0.2 g/L) in the feed phase on metal transport have been investigated. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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13 pages, 3359 KiB

Open AccessArticle

Antibacterial, Antifungal and Ecotoxic Effects of Ammonium and Imidazolium Ionic Liquids Synthesized in Microwaves

by Jana Fojtášková, Ivan Koutník, Martina Vráblová, Hana Sezimová, Milan Maxa, Lucie Obalová and Petr Pánek

Molecules 2020, 25(21), 5181; https://doi.org/10.3390/molecules25215181 - 6 Nov 2020

Cited by 11 | Viewed by 2777

Abstract

Ionic liquids are increasingly used for their superior properties. Four water-immiscible ionic liquids (butyltriethylammonium bis(trifluoromethylsulfonyl)imide, octyltriethylammonium bis(trifluoromethylsulfonyl)imide, dodecyltriethylammonium bis(trifluoromethylsulfonyl)imide, butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and their water miscible precursors (bromides) were synthesized in a microwave reactor and by conventional heating. The best conditions for microwave-assisted synthesis [...] Read more.

Ionic liquids are increasingly used for their superior properties. Four water-immiscible ionic liquids (butyltriethylammonium bis(trifluoromethylsulfonyl)imide, octyltriethylammonium bis(trifluoromethylsulfonyl)imide, dodecyltriethylammonium bis(trifluoromethylsulfonyl)imide, butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and their water miscible precursors (bromides) were synthesized in a microwave reactor and by conventional heating. The best conditions for microwave-assisted synthesis concerning the yield and the purity of the product are proposed. The heating in the microwave reactor significantly shortened the reaction time. Biocide and ecotoxic effects of synthesized ionic liquids and their precursors were investigated. All tested compounds had at least a little effect on the growth or living of microorganisms (bacteria or mold). The precursor dodecyltriethylammonium bromide was found to be the strongest biocide, but posed a risk to the aquatic environment due to its relatively high EC₅₀ value in the test with Vibrio fischeri. We assumed that apart from the alkyl chain length, the solubility in water, duration of action, or type of anion can influence the final biocide and ecotoxic effect. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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11 pages, 575 KiB

Open AccessArticle

Deep Eutectic Solvent-Based Microextraction of Lead(II) Traces from Water and Aqueous Extracts before FAAS Measurements

by Mohamed A. Habila, Najla AlMasoud, Taghrid S. Alomar, Zeid A. AlOthman, Erkan Yilmaz and Mustafa Soylak

Molecules 2020, 25(20), 4794; https://doi.org/10.3390/molecules25204794 - 19 Oct 2020

Cited by 27 | Viewed by 3361

Abstract

Microextraction procedures for the separation of Pb(II) from water and food samples extracts were developed. A deep eutectic solvent composed of α-benzoin oxime and iron(III) chloride dissolved in phenol was applied as a phase separator support. In addition, this deep eutectic mixture worked [...] Read more.

Microextraction procedures for the separation of Pb(II) from water and food samples extracts were developed. A deep eutectic solvent composed of α-benzoin oxime and iron(III) chloride dissolved in phenol was applied as a phase separator support. In addition, this deep eutectic mixture worked as an efficient extractor of Pb(II). The developed microextraction process showed a high ability to tolerate the common coexisting ions in the real samples. The optimum conditions for quantitative recoveries of Pb(II) from aqueous extracts were at pH 2.0, conducted by adding 150 µL from the deep eutectic solvent. The quantitative recoveries were obtained with various initial sample volumes up to 30 mL. Limits of detection and limits of quantification of 0.008 and 0.025 µg L⁻¹ were achieved with a relative standard deviation (RSD%) of 2.9, which indicates the accuracy and sensitivity of the developed procedure. Recoveries from the reference materials, including TMDA 64.2, TMDA 53.3, and NCSDC-73349, were 100%, 97%, and 102%, respectively. Real samples, such as tap, lake, and river water, as well as food samples, including salted peanuts, chickpeas, roasted yellow corn, pistachios, and almonds, were successfully applied for Pb(II) analysis by atomic absorption spectroscopy (AAS) after applying the developed deep eutectic solvent-based microextraction procedures. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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6 pages, 1514 KiB

Open AccessCommunication

Reducing the Competition: A Dual-Purpose Ionic Liquid for the Extraction of Gallium from Iron Chloride Solutions

by Luke M. M. Kinsman, Carole A. Morrison, Bryne T. Ngwenya and Jason B. Love

Molecules 2020, 25(18), 4047; https://doi.org/10.3390/molecules25184047 - 4 Sep 2020

Cited by 8 | Viewed by 3634

Abstract

The separation of gallium from iron by solvent extraction from chloride media is challenging because the anionic chloridometalates, FeCl₄⁻ and GaCl₄⁻, display similar chemical properties. However, we report here that the selective separation of gallium from iron in [...] Read more.

The separation of gallium from iron by solvent extraction from chloride media is challenging because the anionic chloridometalates, FeCl₄⁻ and GaCl₄⁻, display similar chemical properties. However, we report here that the selective separation of gallium from iron in HCl solution can be achieved using the dual-purpose ionic liquid methyltrioctylammonium iodide in a solvent extraction process. In this case, the reduction of Fe³⁺ to Fe²⁺ by the iodide counterion was found to inhibit Fe transport, facilitating quantitative Ga extraction by the ionic liquid with minimal Fe extraction from 2 M HCl. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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14 pages, 1548 KiB

Open AccessArticle

Effect of the Addition of Amine in Organophosphorus Compounds on Molecular Structuration of Ionic Liquids–Application to Solvent Extraction

by Soumaya Gmar, Fabrice Mutelet and Alexandre Chagnes

Molecules 2020, 25(11), 2584; https://doi.org/10.3390/molecules25112584 - 2 Jun 2020

Cited by 8 | Viewed by 2718

Abstract

Variation of dynamic viscosity, density and enthalpy as a function of mole fraction of amine (tri-n-octylamine, triisooctylamine, bis(2-ethylhexyl)amine) in bis(2-ethylhexyl) phosphoric acid (D2EHPA) or Cyanex 272, (bis(2,4,4-trimethylpentyl)phosphinic acid) has been determined at 25 °C. Valuable information regarding structuration and destabilization of the corresponding [...] Read more.

Variation of dynamic viscosity, density and enthalpy as a function of mole fraction of amine (tri-n-octylamine, triisooctylamine, bis(2-ethylhexyl)amine) in bis(2-ethylhexyl) phosphoric acid (D2EHPA) or Cyanex 272, (bis(2,4,4-trimethylpentyl)phosphinic acid) has been determined at 25 °C. Valuable information regarding structuration and destabilization of the corresponding ionic liquids has been deduced from these data. A simple model describing the variation of dynamic viscosity as a function of mole fraction of amine has been used to determine the speciation in these mixtures. Extraction tests of cobalt(II) and nickel(II) by D2EHPA-amine mixtures have shown the highest cobalt(II)-nickel(II) selectivity has been achieved with D2EHPA-2-ethylhexylamine mixture as cobalt(II) extraction efficiency of 77% was obtained, while no significant nickel(II) extraction was observed at a chloride concentration of 3 mol·L⁻¹. Full article

(This article belongs to the Special Issue Ionic Liquids and Deep Eutectic Solvents for Wastewater and Secondary Sources Treatment)

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