Ionic Liquid Research Articles

High-performance dicationic ionic liquids based on imidazolium and quaternary ammonium for phenol extraction

Phenolic compounds serve as crucial chemical raw materials abundant in coal tar, so it is of great economic value to extract phenolic compounds from coal tar. Ionic liquids (ILs) are regarded as desirable extractants in this separation field due to considerable advantages over traditional methods. Compared to traditional mono-cationic ILs, dicationic ionic liquids (DILs) exhibit outstanding thermal stability and a wider operating temperature range. Our research focused on developing DILs based on typical imidazolium and quaternary ammonium structures for phenol separation, examining the impact of the methylene chain length between the cations on the extraction efficiency. Hydrogen bonding and π-π interactions between DILs and phenol were also investigated as driving forces in the extraction process. 1-methyl-3-(3-(trimethylammonio)propyl)-1H-imidazol-3-ium bromide ([MIMC3N111][Br]2) with a moderate chain length was selected as the optimal extractant due to its weaker coulomb force inside the DIL, facilitating stronger hydrogen bonding with phenol compared to the other two DILs. Under optimized conditions, [MIMC3N111][Br]2 exhibited the highest extraction efficiency of 96.03 % in model oil (toluene and phenol) with a phenol content of 200 g dm−3 and the DIL to phenol mole ratio was only around 0.3. [MIMC3N111][Br]2 also featured excellent recyclability, maintaining high extraction efficiency through multiple cycles. Importantly, its lower solubility in oil-phenol mixtures compared to mono-cationic ILs significantly reduced contamination of the oil phase. The DILs in this work can exhibit significant potential for separating phenolic compounds with certain advantages.

Optimizing Environmentally-Friendly oil Recovery: Synergies of Imidazolium-Based ionic liquids and carboxymethylcellulose hydrogels

This research focuses on the combined effectiveness of imidazolium-based ionic liquids (ILs) with triflate anion and carboxymethylcellulose-based hydrogels (CBHs) for environmentally friendly oil recovery. The selection of ILs was based on a review of existing literature, and their performance in extreme reservoir conditions was evaluated by studying parameters like concentration, salinity, temperature, and alkyl chain length. A new material,ionic liquid based CBH (CBHIL), was synthesized by incorporating ILs into hydrogels, and its structure was analyzed using various tests including FTIR, TGA, rheology, and SEM morphology tests. To evaluate the performance in EOR processes, particularly in carbonate rocks, a multilayer glass micromodel with permeabilities was designed. The objective was to determine the water-absorbing capacity, equilibrium swelling, and contact angle change, ultimately leading to increased oil recovery. The results indicated that 1-hexyl-3-methylimidazolium triflate (IL6) was able to reduce interfacial tension (IFT) to a minimum of 6.5 mN/m, surpassing 1-butyl-3-methylimidazolium triflate (IL4), especially at high temperatures and salinity. The emulsion stability of IL6 in the oil phase was also confirmed. CBH was used as a carrier for ILs, exhibiting thermal resistance up to 120 °C. Its porous structure and significant equilibrium swelling of up to 1550 % under harsh reservoir conditions were observed. By incorporating IL in the CBHIL-C6 structure, the linear viscoelastic range of CBH increased from 52.2 % to 170 % strain, and effectively altered carbonate rocks to become completely water-wet, reducing the contact angle from 115.4° to 44.62°. The combination of these two substances led to a maximum recovery of 79.85 % of the original oil in place, a significantly superior outcome compared to separate injection of the substances. Thus, these new compounds demonstrate promising potential for EOR applications in challenging reservoir conditions.

Synthesis and application of merrifield resin based supported ionic liquids as organocatalyst for the greener synthesis of bio-active triazoles

A green and highly efficient catalysts based on merrifield resin supported acidic ionic liquids (MRBT-SILs) were synthesized using merrifield resin (non-toxic and chemically inert) and benzothiazole. The application of MRBT-SILs for the greener synthesis of 1,2,4-triazole-3-thiones or 1,2,4-triazole-3-oxones from condensation of ketones and thiosemicarbazide or semicarbazide respectively in 60% ethanol under ultra-sonication was studied. The protocol so developed has many additional benefits compared to those reported in previous articles such as smooth reaction, use of alcohol as solvent, good yield, ambient temperature, an easy workup procedure, catalyst recyclability, and high atom economy, making it highly efficient for synthesis as it obeys green chemistry principles. Further, catalyst could be reused up to eight cycles without any loss of its catalytic activity.

Ionic liquid additive induced holistic trap-passivation for enhanced charge transport in lead-halide perovskite-based transistors

Incorporating ionic liquid additives into perovskite-based electronic devices has been considerably demonstrated to improve device performance and stability via synergistic passivation effects. However, the advantages and understanding of ionic additives in perovskite field-effect transistors (FETs) have been explored far less. Herein, holistic trap-passivation is reported in a poly(3-hexylthiophene)-functionalized electrolyte-gated perovskite FETs with a solid-state ionic liquid (ss-IL) additive. The optimized ss-IL-incorporated methylammonium lead iodide (MAPbI3/ss-IL) FETs exhibited remarkable hole mobility of over 30 cm2 V−1 s−1 at an operating voltage of –1.5 V, attributed to suppressed lead/iodine vacancies and related traps and exhibiting excellent operational stability under ambient conditions with recoverable complex hysteresis behavior. These results demonstrate the promising synergistic impacts of the proposed trap engineering and provide a fundamental understanding of charge transport physics in doped perovskite semiconductors, essential for advancing their application as transistor-based devices.

High-value conversion of invasive plant into nitrogen-doped porous carbons for high-performance supercapacitors

Given the harm caused by invasive plants to the environment and the high cost of treatment, we propose high-value transformation and utilization for invasive plants. Highly porous carbon derived from invasive plant (Canada goldenrod) was successfully synthesized through a feasible and green carbonization approach, which was firstly utilized as supercapacitor electrode. It is found that the addition of nitrogen (N)-rich chlorella could positively increase the N content and considerably boost the specific surface area up to 2231.41 m2 g-1 for the resultant Carbon-GC1-800, which are crucial factors for accelerating the ion transport and improving the capacitive behaviors. Notably, Carbon-GC1-800 exhibits the highest ratio (70.9%) of microporous volume to total pore volume. The electrochemical properties of Carbon-GC1-800 electrode exhibits an outstanding specific capacitance of 388.2Fg-1 at a current density of 0.5Ag-1 and a superb rate capability of 75.7% from 0.5Ag-1 to 10Ag-1. The assembled symmetric supercapacitor with ionic liquid as electrolyte demonstrates the exceptional maximum power density of 8753.7Wkg-1 and peak energy density of 59.3Whkg-1. This study presents the novel ideas and effective techniques to produce porous carbons for energy storage from invasive plant resources.

Application of ionic liquids as co-solvent for oil extraction from desert date

The extraction of oil from Balanites seed (desert date) using ultrasound-assisted extraction was investigated using organic solvent (ethyl acetate) and ionic liquid as co-solvent. The study found that an optimum oil yield of 28.67 % was obtained using a seed to solvent ratio of 1:6, an extraction temperature of 50 °C and an extraction time of 30 min when ethyl acetate was used as the sole solvent in the extraction system. Different types of ionic liquids as co-solvents were screened in this study and an improvement of oil yield (3–6 %) was observed using 1-butyl-3-methylimidazolium acetate. Additionally, the presence of ionic liquid as a co-solvent during the extraction process could achieve a similar oil yield at a lower extraction temperature. This indicates the potential breakdown of the lignocellulosic cell wall of the seed using 1-butyl-3-methylimidazolium acetate. The presence of 1-butyl-3-methylimidazolium acetate as co-solvent can enhance the penetration of the organic solvent into the Balanites seed matrix for oil extraction and can reduce the energy required for the extraction process.

Convolution Analysis in Electrodeposition

Convolution is a well established method for data analysis for electrochemical processes where both product and reactants are soluble. Advantages of convolution analysis include (a) facile evaluation of kinetic and system parameters, (b) ready corrections for nonfaradaic uncompensated resistance and double layer charging, (c) track of surface concentrations with time, independent of the voltage perturbation sequence, and (d) ease of convolution calculation from digitized current data. Here, equations are derived for convolution of electrodeposition data and a data analysis protocol is presented. Advantages are found for convolution analysis in electrodeposition. Parameters that can be determined from convolution analysis in electrodeposition are standard heterogeneous rate constant k 0 and exchange current density j 0, transfer coefficients α and β, formal potential E0′ , resistance to charge transfer, and diffusion coefficient of the solution soluble reactant D M . Convolution in electrodeposition is illustrated for silver deposited from an ionic liquid onto a glassy carbon electrode, where experimental data are tracked cyclic voltammetrically.

DBN-based molecular solvents for highly efficient and reversible CO2 capture

Reducing greenhouse gas emissions is a crucial step in mitigating global warming. Carbon dioxide (CO2) represents one of the most pivotal greenhouse gases contributing to climate change. Many researchers are actively engaged in the development of effective and reversible CO2 absorbents to control and reduce CO2 gas emissions. In this paper, we synthesized a series of molecular solvents (MSs) based on the superbase 1,5-diazabicyclo [4.3.0]-5-nonene (DBN) and used them for CO2 capture. The CO2 capture capacity of MSs composed of DBN and different alcohols was systematically investigated, with DBN-Methanol (1:1.25) demonstrating superior absorption performance by achieving a maximum absorption capacity of 0.263 g CO2/g MS. The effects of temperature, pressure, the molar ratio of the hydrogen bond acceptor (HBA) to hydrogen bond donor (HBD), and moisture on the absorption process were studied. The experimental results were corroborated by NMR spectra analysis and FTIR spectra analysis, confirming that these MSs can effectively react with CO2 to produce carbonate and carbamate compounds through synergistic absorption involving hydroxyl group as primary component and amino group as secondary component. In addition, it is worth noting that the MSs studied in this work exhibit only glass transition at low temperatures and transform into ionic liquids (ILs) after capturing CO2, resulting in a significant increase in conductivity and demonstrating considerable electrochemical potential.

Emission based response of Er3+, Tb3+, and Er3+-Tb3+ co-doped 1393 bioactive glasses along with HPTS towards CO2

The HPTS serves as a versatile tool in pH and CO2 sensing studies, as well as in cell biology studies of various processes. However, the long-term photostability of HPTS as a fluorescent dye is an important consideration in its use, especially for long-term applications. In this work, sol–gel synthesized Er3+, Tb3+ and Er3+: Tb3+ co-doped 1393 bioactive glass particles were incorporated with the HPTS in the presence of ionic liquid in an ethyl cellulose matrix. The interaction of the bioactive glasses with the HPTS was investigated by steady-state luminescence and excited-state lifetime measurements. The prepared composites showed linearizable responses when exposed to different CO2 concentrations. High I0/I100 values (87, 109 and 115) were obtained for the binary blends of HPTS and bioactive glasses. When the imidazolium-based IL was used together with the offered composites, we observed improved stability and longevity for the HPTS up to 315 days. The incorporation of imidazolium-based ionic liquids as additives in HPTS-based fluorescence assays together with the bioactive glasses holds promise for enhancing the photostability of the HPTS and improving the reliability and longevity of fluorescence signals in various research applications.

Construction of a waste-derived graphite electrode integrated IL/Ni-MOF flowers/Co3O4 NDs for specific enrichment and signal amplification to detect aspartame

A novel and cost-efficient electrochemical sensor was designed by immobilizing IL/Ni-MOF/Co3O4 nanodiamonds on the graphite (GE) electrode, marking the first application for the detection of aspartame. The graphite electrode was extracted and recycled from discharged batteries to serve as a working electrode. The nanocomposite features unique Co3O4 nanodiamonds, generated using Coriandrum sativum seed extract, alongside Ni-metal organic framework (MOF), which were synthesized through a solvothermal method. The conductivity and stability of the electrochemical sensor were enhanced through the incorporation of the ionic liquid (IL) ([BMIM][MeSO4]. The phytochemical profile of Coriandrum sativum seed extract, analyzed by GC-MS, identified key compounds involved in the synthesis of Co3O4 nanodiamonds. A comprehensive characterization of the nanocomposite was performed using UV-Vis, FTIR, DLS, Zeta potential, XRD, XPS, FE-SEM, TEM, optical profilometry, and AFM to confirm the structural and elemental modifications. Electrochemical characterization of the bare and modified electrodes was conducted through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The GE/IL/Ni-MOF/Co3O4 nanodiamonds modified electrode displayed enhanced electroanalytical performance for aspartame detection, characterized by signal amplification at +7.0V. Quantitative analysis by Differential Pulse Voltammetry (DPV) and Square Wave Voltammetry (SWV) revealed a linear detection range of 3-15µM for aspartame. A comparison of SWV and DPV revealed superior analytical performance for SWV, with limits of detection (LOD) and limit of quantification (LOQ) values of 1.02µM and 3.1µM (R2 = 0.993) compared to 1.81µM and 5.5µM (R2 = 0.986) for DPV. This study reveals the excellent adsorption capabilities of Ni-MOF and Co3O4 nanodiamonds (Co3O4 NDs), attributed to their high porosity and large surface area, paving the way for the development of affordable sensing devices for artificial sweeteners.

Investigation of the double layer structure of 1-butyl-3-methylimidazolium thiocyanate at the air-water interface using sum-frequency generation vibrational spectroscopy.

The interfacial structure and adsorption behavior of 1-butyl-3-methylimidazolium thiocyanate ionic liquids (ILs) aqueous solutions were investigated using sum-frequency generation vibrational spectroscopy (SFG-VS) and surface tension measurements. Polarization-dependent measurements revealed a dramatic increase in the SFG signal for both CH and CN stretching modes with increasing ILs concentration, reaching a maximum at a mole fraction of 0.01. This concentration dependence was accompanied by a dramatic drop in surface tension. Upon further increasing the concentration, surface tension varied slightly and reached a constant value, while the SFG signal decreased significantly. Quantitative polarization analysis showed that as the bulk concentration increased, the apparent molecular orientation of the SCN- transition dipole at the interface changed from 51° to 46°, and the tilt angle of CH3 group of the butyl chain attached to the imidazole cationic ring changed from 18° to 32°. The decrease in the SFG signal can be explained by the formation of a double layer adsorption structure at the air/water interface. It was also demonstrated that the anions were adsorbed at the interface simultaneously with the cationic group, rather than by successive adsorption as proposed in a previous study. Using the Shereshefsky model, the thermodynamic Gibbs free energy of adsorption deduced from surface tension data was compared with SFG results.

A multi-purpose dressing based on resveratrol-loaded ionic liquids/gelatin methacryloyl hydrogel for enhancing diabetic wound healing

Diabetic wound (DW) is a multifaceted challenge, characterized by persistent bacterial infections and compromised angiogenesis. To address these issues and enhance DW healing, we developed a novel strategy using a photo-crosslinked hydrogel system composed of ionic liquids (ILs) and gelatin methacryloyl (GelMA) loaded with resveratrol (Res). The ILs/GelMA hydrogel was fabricated via a simple photo-crosslinking process, resulting in desirable mechanical properties, biocompatibility, and controlled release kinetics. Res was incorporated into the hydrogel matrix (ILs/GelMA@Res) to ensure sustained release, facilitating angiogenesis and accelerating wound healing. In vitro studies demonstrated that the ILs/GelMA@Res hydrogel exhibited potent antibacterial activity against Staphylococcus aureus and Escherichia coli, inhibiting bacterial growth and biofilm formation. Furthermore, the sustained release of Res from the hydrogel promoted angiogenesis by activating the PI3K/AKT signaling pathways associated with VEGF and FGF, enhancing endothelial cell proliferation, migration, and tube formation. In a DW mice model, the ILs/GelMA@Res hydrogel demonstrated accelerated wound closure, reduced inflammation, and robust neovascularization. This multifunctional hydrogel-based delivery system holds considerable potential for clinical translation, offering a safe and effective treatment modality for diabetic patients with chronic wounds.

Process Development of a Liquid-Gated Graphene Field-Effect Transistor Gas Sensor for Applications in Smart Agriculture

A compact, multi-channel ionic liquid-gated graphene field-effect transistor (FET) has been proposed and developed in our work for on-field continuous monitoring of nitrate nitrogen and other nitrogen fertilizers to achieve sustainable and efficient farming practices in agriculture. However, fabricating graphene FETs with easy filling of ionic liquids, minimal graphene defects, and high process yields remains challenging, given the sensitivity of these devices to processing conditions and environmental factors. In this work, two approaches for the fabrication of our graphene FETs were presented, evaluated, and compared for high yields and easy filling of ionic liquids. The process difficulties, major obstacles, and improvements are discussed herein in detail. Both devices, those fabricated using a 3 μm-thick CYTOP® layer for position restriction and volume control of the ionic liquid and those using a ~20 nm-thick photosensitive hydrophobic layer for the same purpose, exhibited typical FET characteristics and were applicable to various application environments. The research findings and experiences presented in this paper will provide important references to related societies for the design, fabrication, and application of liquid-gated graphene FETs.

Jellyfish-Inspired Polyurea Ionogel with Mechanical Robustness, Self-Healing, and Fluorescence Enabled by Hyperbranched Cluster Aggregates.

Ionogels are promising for soft iontronics, with their network structure playing a pivotal role in determining their performance and potential applications. However, simultaneously achieving mechanical toughness, low hysteresis, self-healing, and fluorescence using existing network structures is challenging. Drawing inspiration from jellyfish, we propose a novel hierarchical crosslinking network structure design for in situ formation of hyperbranched cluster aggregates (HCA) to fabricate polyurea ionogels to overcome these challenges. Leveraging the disparate reactivity of isocyanate groups, we induce the in situ formation of HCA through competing reactions, enhancing toughness and imparting the clustering-triggered emission of ionogel. This synergy between supramolecular interactions in the network and plasticizing effect in ionic liquid leads to reduced hysteresis of the ionogel. Furthermore, the incorporation of NCO-terminated prepolymer with dynamic oxime-urethane bonds (NPU) enables self-healing and enhances stretchability. Our investigations highlight the significant influence of HCA on ionogel performance, showcasing mechanical robustness including high strength (3.5 MPa), exceptional toughness (5.5 MJ m-3), resistance to puncture, and low hysteresis, self-healing, as well as fluorescence, surpassing conventional dynamic crosslinking approaches. This network design strategy is versatile and can meet the various demands of flexible electronics applications.

The Effect of TiO2 Nanoparticles and the Liquid-Phase Therapy on the Resistance of the Interphase Lithium/Polymer Electrolyte with the Introduction of Ionic Liquid

The Effect of TiO2 Nanoparticles and the Liquid-Phase Therapy on the Resistance of the Interphase Lithium/Polymer Electrolyte with the Introduction of Ionic Liquid

Room-temperature [C2mim]OAc crystal

1-Ethyl-3-methylimidazolium acetate ([C2mim]OAc) is the most commonly used cellulose-dissolving ionic liquid and has been extensively studied for biorefinery applications. Although [C2mim]OAc is generally considered to be a liquid, we found [C2mim]OAc crystals at room temperature (around 25°C) with a melting point of 44°C. A plausible reason for the crystallization is shearing stress. [C2mim]OAc seed crystals led to the crystallization of liquid [C2mim]OAc.

Phase behavior of aqueous two-phase systems formed with cholinium-based magnetic ionic liquids: Experimental insights and theoretical correlations

In this work, three cholinium-based MILs were synthesized, characterized and successfully applied to construct the magnetically responsive aqueous two-phase system (ATPs). This ATPs combined the advantages of ILs and magnetic responsiveness, and showed great potential in the field of extraction and separation. Phase behavior for the magnetic ionic liquid aqueous two-phase systems (MIL-ATPSs) containing [N 1 1n 2OH] [TEMPO-OSO3] + salts + water was investigated experimentally at different temperatures. Merchuk equation was adopted to fit the experimental binodal data with satisfactory correlation performances. The effects of the structure of MILs, temperature and types of salts on the phase behavior were evaluated. Investigation on the phase separation mechanism showed that the phase formation was affected by the structure and viscosity of MILs. The salting-out effect is recognized as the major force for phase separation, which is closely related to the Gibbs free energy of hydration (ΔhydG) and entropy of hydration (ΔhydS) of salts. In addition, a larger biphasic area was obtained by increasing the temperature, indicating the phase separation process was endothermic and entropically driven. The binodal curve at different temperature confirms that this MIL-ATPs has low critical solution temperature (LCST) phase transition behavior. All these experimentally measured data and the theoretical correlations can provide meaningful and valuable information that may promote further research and application.

Brønsted Acidic Ionic Liquid: An Efficient Organocatalyst for the Synthesis of Pyrrolo[1,2-a]indoles under Neat Conditions

AbstractA new synthetic approach has emerged for constructing 9H-pyrrolo[1,2-a]indole scaffolds by the reactions between indoles and chalcones under metal- and solvent-free conditions at 80 °C. The reaction occurs smoothly in the presence of a Brønsted acidic ionic liquid, 1-methyl-3-(4-sulfobutyl)-1H-imidazol-3-ium tosylate, as a catalyst, permitting the synthesis of the desired products with satisfactory yields. The developed protocol is applicable to the construction of biologically important pyrrolo[1,2-a]indole derivatives from easily accessible chalcones having various substituents. The process commences with Michael addition to chalcones, followed by annulations induced by the elimination of a water molecule, yielding the 9H-pyrrolo[1,2-a]indole scaffolds. Several control experiments were carried out to achieve a better understanding of the reaction pathway. The feasibility of recycling the catalyst was also demonstrated. This method produces water as the sole byproduct and represents a green synthetic protocol. The clean reaction, easily accessible reactants, and the metal- and solvent-free and environmentally friendly reaction conditions are the notable advantages of this procedure.

Ionic liquid-functionalized ZnO nanomaterial: Multifunctional additives enhancing tribological performance and corrosion resistance in ester oil

A multifunctional nanomaterial (ZnO-IL), comprising zinc oxide modified with corrosion-resistant ionic liquid groups, was designed and synthesized. It was used as an additive in bis(2-ethylhexyl) sebacate (DIOS) to evaluate its tribological and corrosion resistance properties, and compared with the commercial additive sulfurized isobutylene (SIB). ZnO-IL exhibited good solubility and thermal stability in DIOS. Lubricants containing ZnO-IL showed excellent anti-wear performance under various loads and temperatures. Its deposition on metal surfaces and the synergistic action of benzotriazole groups in the anions effectively prevented corrosion on the surfaces of metal friction pairs, thereby addressing the challenge of friction pair corrosion caused by the hydrolysis of ester-based oils. The ZnO-IL nanomaterial rapidly formed an organic-inorganic multilayer adsorption film on metal surfaces through electrostatic interactions. During friction, a boundary lubrication film composed of ZnO deposition and friction chemical reaction films was formed, thereby avoiding direct metal contact, reducing contact pressure, and exhibiting outstanding friction reduction and anti-wear properties.

Investigation of the physicochemical and thermodynamic characteristics of imidazole ionic liquids with water and ethanol mixtures

Investigation of the physicochemical and thermodynamic characteristics of imidazole ionic liquids with water and ethanol mixtures