International Journal of Molecular Sciences

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16 pages, 4398 KiB

Open AccessArticle

Separation of Anionic Chlorinated Dyes from Polluted Aqueous Streams Using Ionic Liquids and Their Subsequent Recycling

by Barbora Kamenická, Petr Švec and Tomáš Weidlich

Int. J. Mol. Sci. 2023, 24(15), 12235; https://doi.org/10.3390/ijms241512235 - 31 Jul 2023

Cited by 7 | Viewed by 1081

Abstract

The effect of ionic liquids on the separation of chlorinated anionic dyes such as Mordant Blue 9 (MB9) or Acid Yellow 17 (AY17) via ion exchange has been investigated in model aqueous solutions that simulate wastewater from the textile dyeing industry. The effect [...] Read more.

The effect of ionic liquids on the separation of chlorinated anionic dyes such as Mordant Blue 9 (MB9) or Acid Yellow 17 (AY17) via ion exchange has been investigated in model aqueous solutions that simulate wastewater from the textile dyeing industry. The effect of ionic liquids chemical nature on the separation efficiency of mentioned dyes has been compared. It was found that especially ionic liquid based on quaternary ammonium salts comprising two or three long alkyl chains bound to the quaternary ammonium nitrogen (typically benzalkonium chloride or Aliquat 336) are very effective for the separation of both studied MB9 and AY17 from aqueous solution. In addition, the innovative technique has been developed for the reactivation of spent ionic liquids which is based on the chemical reduction of the formed ion pairs using NaBH₄/NiSO₄, NaBH₄/Na₂S₂O₅ or Raney Al-Ni alloy/NaOH. Thus, only NaBH₄/NiSO₄ in co-action with Al-Ni alloy enables both effective reduction of the azo bond and subsequent hydrodechlorination of emerging chlorinated aromatic amines. The efficiency of tested dyes separation or regeneration of ion pairs was evaluated by determination of the absorbance at wavelength of the maximum absorbance, of the Chemical Oxidation Demand (COD), and of the Adsorbables Organically bound Halogens (AOX). The formation of ion pairs or products of reduction and hydrodechlorination of these ion pairs has been studied using the ¹H NMR and LC-MS techniques. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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22 pages, 14818 KiB

Open AccessArticle

Synthesis of Ammonium-Based ILs with Different Lengths of Aliphatic Chains and Organic Halogen-Free Anions as Corrosion Inhibitors of API X52 Steel

by Emiliano Cornejo Robles, Octavio Olivares-Xometl, Natalya V. Likhanova, Paulina Arellanes-Lozada, Irina V. Lijanova and Víctor Díaz-Jiménez

Int. J. Mol. Sci. 2023, 24(8), 7613; https://doi.org/10.3390/ijms24087613 - 20 Apr 2023

Cited by 3 | Viewed by 1733

Abstract

In the present work, synthesis and characterization of 15 ionic liquids (ILs) derived from quaternary ammonium and carboxylates were carried out in order to proceed to their evaluation as corrosion inhibitors (CIs) of API X52 steel in 0.5 M HCl. Potentiodynamic tests confirmed [...] Read more.

In the present work, synthesis and characterization of 15 ionic liquids (ILs) derived from quaternary ammonium and carboxylates were carried out in order to proceed to their evaluation as corrosion inhibitors (CIs) of API X52 steel in 0.5 M HCl. Potentiodynamic tests confirmed the inhibition efficiency (IE) as a function of the chemical configuration of the anion and cation. It was observed that the presence of two carboxylic groups in long linear aliphatic chains reduced the IE, whereas in shorter chains it was increased. Tafel-polarization results revealed the ILs as mixed-type CIs and that the IE was directly proportional to the CI concentration. The compounds with the best IE were 2-amine-benzoate of N,N,N-trimethyl-hexadecan-1-ammonium ([THDA⁺][⁻AA]), 3-carboxybut-3-enoate of N,N,N-trimethyl-hexadecan-1-ammonium ([THDA⁺][⁻AI]), and dodecanoate of N,N,N-trimethyl-hexadecan-1-ammonium ([THDA⁺][⁻AD]) within the 56–84% interval. Furthermore, it was found that the ILs obeyed the Langmuir adsorption isotherm model and inhibited the corrosion of steel through a physicochemical process. Finally, the surface analysis by scanning electron microscopy (SEM) confirmed less steel damage in the presence of CI due to the inhibitor–metal interaction. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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10 pages, 2325 KiB

Open AccessCommunication

Ionic Liquid-Supported Photocatalysts: A Reusable Environmentally Friendly Oxidation Reaction System That Uses Air and Light

by Shinichi Koguchi, Haruto Fujita and Yuga Shibuya

Int. J. Mol. Sci. 2023, 24(8), 7141; https://doi.org/10.3390/ijms24087141 - 12 Apr 2023

Viewed by 1470

Abstract

Ionic liquids are used in various fields due to their unique physical properties and are widely utilized as reaction solvents in the field of synthetic organic chemistry. We have previously proposed a new organic synthetic method in which the catalyst and reaction reagents [...] Read more.

Ionic liquids are used in various fields due to their unique physical properties and are widely utilized as reaction solvents in the field of synthetic organic chemistry. We have previously proposed a new organic synthetic method in which the catalyst and reaction reagents are supported on ionic liquids. This method has various advantages, such as the ability to reuse the reaction solvent and catalyst and its facile post-reaction treatment. In this paper, we describe the synthesis of an ionic liquid-supported anthraquinone photocatalyst and the synthesis of benzoic acid derivatives using this system. This synthesis of benzoic acid derivatives via the cleavage of vicinal diols by an ionic liquid-supported anthraquinone photocatalyst is an environmentally friendly process, and furthermore, it has a simple post-reaction process, and the catalyst and solvent can both be reused. To the best of our knowledge, this is the first report on the synthesis of benzoic-acid derivatives via the cleavage of vicinal diols using light and an ionic-liquid-supported catalyst. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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11 pages, 1517 KiB

Open AccessCommunication

On the Use of Pseudo-Protic Ionic Liquids to Extract Gold(III) from HCl Solutions

by Francisco Jose Alguacil and Jose Ignacio Robla

Int. J. Mol. Sci. 2023, 24(7), 6305; https://doi.org/10.3390/ijms24076305 - 27 Mar 2023

Cited by 6 | Viewed by 1314

Abstract

Solvent extraction of gold(III) from HCl media using pseudo-protic ionic liquids (PPILs) dissolved in toluene as the extractant phase is investigated. Three PPILs are generated from the reaction of commercially available amines and 1 M HCl solution and named as pri-NH₂H [...] Read more.

Solvent extraction of gold(III) from HCl media using pseudo-protic ionic liquids (PPILs) dissolved in toluene as the extractant phase is investigated. Three PPILs are generated from the reaction of commercially available amines and 1 M HCl solution and named as pri-NH₂H⁺Cl⁻ (derived from the primary amine Primene 81R), sec-NHH⁺Cl⁻ (derived from the secondary amine Amberlite LA2) and ter-NH⁺Cl⁻ (derived from the tertiary amine Hostarex A327). In the above structures, -NH₂H⁺Cl⁻, -NHH⁺Cl⁻ and -NH⁺Cl⁻ represented the active groups (anion exchangers) of the respective PPIL. In the case of gold(III) extraction, the experimental variables investigated included the equilibration time (2.5–30 min), temperature (20–60 °C), HCl concentrations (1–10 M) in the aqueous phase, gold(III) concentration (0.005–0.05 g/L) in this same phase, and PPILs concentrations in the organic phase. From the experimental data, and using the Specific Interaction Theory, the interaction coefficients (ε) for the pair AuCl₄⁻, H⁺ are estimated for the systems involving the three PPILs. Gold(III) is recovered from the metal-loaded organic phases using sodium thiocyanate solutions, and from these, gold is finally recovered by the precipitation of zero-valent gold (ZVG) nanoparticles. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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29 pages, 22887 KiB

Open AccessArticle

Temperature Effect on the Corrosion Inhibition of Carbon Steel by Polymeric Ionic Liquids in Acid Medium

by Giselle Gómez-Sánchez, Octavio Olivares-Xometl, Paulina Arellanes-Lozada, Natalya V. Likhanova, Irina V. Lijanova, Janette Arriola-Morales, Víctor Díaz-Jiménez and Josué López-Rodríguez

Int. J. Mol. Sci. 2023, 24(7), 6291; https://doi.org/10.3390/ijms24076291 - 27 Mar 2023

Cited by 19 | Viewed by 2434

Abstract

In the present research work, the temperature effect on the corrosion inhibition process of API 5L X60 steel in 1 M H₂SO₄ by employing three vinylimidazolium poly(ionic liquid)s (PILs) was studied by means of electrochemical techniques, surface analysis and computational [...] Read more.

In the present research work, the temperature effect on the corrosion inhibition process of API 5L X60 steel in 1 M H₂SO₄ by employing three vinylimidazolium poly(ionic liquid)s (PILs) was studied by means of electrochemical techniques, surface analysis and computational simulation. The results revealed that the maximal inhibition efficiency (75%) was achieved by Poly[VIMC4][Im] at 308 K and 175 ppm. The PILs showed E_corr displacements with respect to the blank from −14 mV to −31 mV, which revealed the behavior of mixed-type corrosion inhibitors (CIs). The steel micrographs, in the presence and absence of PILs, showed less surface damage in the presence of PILs, thus confirming their inhibiting effect. The computational studies of the molecular orbitals and molecular electrostatic potential of the monomers suggested that the formation of a protecting film could be mainly due to the nitrogen and oxygen heteroatoms present in each structure. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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17 pages, 4115 KiB

Open AccessArticle

Effect of Zwitterionic Additive on Electrode Protection through Electrochemical Performances of Anatase TiO₂ Nanotube Array Electrode in Ionic Liquid Electrolyte

by Aleksandra Roganović, Milan Vraneš, Nikola Cvjetićanin, Xiaoping Chen and Snežana Papović

Int. J. Mol. Sci. 2023, 24(4), 3495; https://doi.org/10.3390/ijms24043495 - 9 Feb 2023

Cited by 7 | Viewed by 2212

Abstract

In this work, a functionalized zwitterionic (ZI) compound 1-butylsulfonate-3-methylimidazole (C₁C₄imSO₃) was synthesized and tested as an additive to LiTFSI/C₂C₂imTFSI ionic liquid-based electrolytes for lithium-ion batteries. The structure and purity of C₁C [...] Read more.

In this work, a functionalized zwitterionic (ZI) compound 1-butylsulfonate-3-methylimidazole (C₁C₄imSO₃) was synthesized and tested as an additive to LiTFSI/C₂C₂imTFSI ionic liquid-based electrolytes for lithium-ion batteries. The structure and purity of C₁C₄imSO₃ were confirmed by NMR and FTIR spectroscopy. The thermal stability of the pure C₁C₄imSO₃ was examined by simultaneous thermogravimetric–mass spectrometric (TG–MS) measurements and differential scanning calorimetry (DSC). The LiTFSI/C₂C₂imTFSI/C₁C₄imSO₃ system was tested as a potential electrolyte for lithium-ion batteries by using anatase TiO₂ nanotube array electrode as the anode material. This electrolyte with 3% C₁C₄imSO₃ showed significant improvement of lithium-ion intercalation/deintercalation properties, such as capacity retention and Coulombic efficiency compared to electrolyte without additive. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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16 pages, 3653 KiB

Open AccessArticle

Probing Surface and Interfacial Tension of Ionic Liquids in Vacuum with the Pendant Drop and Sessile Drop Method

by Ulrike Paap, Bernd Kreß, Hans-Peter Steinrück and Florian Maier

Int. J. Mol. Sci. 2022, 23(21), 13158; https://doi.org/10.3390/ijms232113158 - 29 Oct 2022

Cited by 7 | Viewed by 2079

Abstract

We report on the surface and interface tension measurements of the two ionic liquids (ILs) [C₈C₁Im][PF₆] and [m(PEG_n)₂Im]I (n = 2, 4, 6) in a surface science approach. The measurements were performed [...] Read more.

We report on the surface and interface tension measurements of the two ionic liquids (ILs) [C₈C₁Im][PF₆] and [m(PEG_n)₂Im]I (n = 2, 4, 6) in a surface science approach. The measurements were performed in a newly developed and unique experimental setup, which allows for surface tension (ST) measurements using the pendant drop method and for contact angle measurements using the sessile drop method under the well-defined conditions of a high vacuum (from 10⁻⁷ mbar). The setup also allows for in vacuum transfer to an ultrahigh vacuum system for surface preparation and analysis, such as in angle-resolved X-ray photoelectron spectroscopy. For [C₈C₁Im][PF₆], we observe a linear decrease in the surface tension with increasing temperature. The ST measured under high vacuum is consistently found to be larger than under ambient conditions, which is attributed to the influence of water uptake in air by the IL. For [m(PEG_n)₂Im]I (n = 2, 4, 6), we observe a decrease in the ST with increasing polyethylene glycol chain length in a vacuum, similar to very recent observations under 1 bar Argon. This decrease is attributed to an increasing enrichment of the PEG chains at the surface. The ST data obtained under these ultraclean conditions are essential for a fundamental understanding of the relevant parameters determining ST on the microscopic level and can serve as a benchmark for theoretical calculations, such as molecular dynamic simulations. In addition to the ST measurements, proof-of-principle data are presented for sessile drop measurements in HV, and a detailed description and characterization of the new setup is provided. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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13 pages, 1652 KiB

Open AccessArticle

New Insights into the Thermal Stability of 1-Butyl-3-methylimidazolium-Based Ionic Liquids

by Artyom V. Belesov, Natalya V. Shkaeva, Mark S. Popov, Tatyana E. Skrebets, Anna V. Faleva, Nikolay V. Ul’yanovskii and Dmitry S. Kosyakov

Int. J. Mol. Sci. 2022, 23(18), 10966; https://doi.org/10.3390/ijms231810966 - 19 Sep 2022

Cited by 8 | Viewed by 2899

Abstract

One of the most promising applications of ionic liquids (ILs) with 1-butyl-3-methylimidazolium (bmim) cation is based on their unique ability to dissolve and fractionate lignocellulosic biomass, allowing for the development of green biorefining technologies. A complete dissolution of lignocellulose requires prolonged treatment at [...] Read more.

One of the most promising applications of ionic liquids (ILs) with 1-butyl-3-methylimidazolium (bmim) cation is based on their unique ability to dissolve and fractionate lignocellulosic biomass, allowing for the development of green biorefining technologies. A complete dissolution of lignocellulose requires prolonged treatment at elevated temperatures, which can cause the partial degradation of ILs. In the present study, a combination of various analytical techniques (GC-MS, HPLC-HRMS, 2D-NMR, synchronous thermal analysis) was used for the comprehensive characterization of bmim acetate, chloride, and methyl sulfate degradation products formed at 150 °C during 6- and 24-h thermal treatment. A number of volatile and non-volatile products, including monomeric and dimeric alkyl substituted imidazoles, alcohols, alkyl amines, methyl and butyl acetates, and N-alkylamides, was identified. By thermal lability, ILs can be arranged in the following sequence, coinciding with the decrease in basicity of the anion: [bmim]OAc > [bmim]Cl > [bmim]MeSO₄. The accumulation of thermal degradation products in ILs, in turn, affects their physico-chemical properties and thermal stability, and leads to a decrease in the decomposition temperature, a change in the shape of the thermogravimetric curves, and the formation of carbon residue during pyrolysis. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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Review

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19 pages, 3429 KiB

Open AccessReview

Polyurethanes Modified by Ionic Liquids and Their Applications

by Xue Wang, Zhenjie Zhao, Meiyu Zhang, Yongri Liang and Yingdan Liu

Int. J. Mol. Sci. 2023, 24(14), 11627; https://doi.org/10.3390/ijms241411627 - 19 Jul 2023

Cited by 7 | Viewed by 2905

Abstract

Polyurethane (PU) refers to the polymer containing carbamate groups in its molecular structure, generally obtained by the reaction of isocyanate and alcohol. Because of its flexible formulation, diverse product forms, and excellent performance, it has been widely used in mechanical engineering, electronic equipment, [...] Read more.

Polyurethane (PU) refers to the polymer containing carbamate groups in its molecular structure, generally obtained by the reaction of isocyanate and alcohol. Because of its flexible formulation, diverse product forms, and excellent performance, it has been widely used in mechanical engineering, electronic equipment, biomedical applications, etc. Through physical or chemical methods, ionic groups are introduced into PU, which gives PU electrical conductivity, flame-retardant, and antistatic properties, thus expanding the application fields of PU, especially in flexible devices such as sensors, actuators, and functional membranes for batteries and gas absorption. In this review, we firstly introduced the characteristics of PU in chemical and microphase structures and their related physical and chemical performance. To improve the performance of PU, ionic liquids (ILs) were applied in the processing or synthesis of PU, resulting in a new type of PU called ionic PU. In the following part of this review, we mainly summarized the fabrication methods of IL-modified PUs via physical blending and the chemical copolymerization method. Then, we summarized the research progress of the applications for IL-modified PUs in different fields, including sensors, actuators, transistors, antistatic films, etc. Finally, we discussed the future development trends and challenges faced by IL-modified PUs. Full article

(This article belongs to the Special Issue Advances in Ionic Liquids and Their Various Applications)

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