Ammonium Ionic Liquids Research Articles

Visualizing and Understanding the Ionic Liquid-Mediated Polybromide Electrochemistry for Aqueous Zinc-Bromine Redox Batteries.

Aqueous zinc-bromine redox systems possess multiple merits for scalable energy storage. Applying bromine complexing agents shows effectiveness in alleviating the key challenge of ubiquitous crossover of reactive liquid bromine species, while the underlying microscopic mechanism requires a deep understanding to engineer better complexing electrochemistry. Herein, taking a series of quaternary ammonium ionic liquids (methyl4NBr, ethyl4NBr, propyl4NBr, and butyl4NBr) as a redox mediator model, operando optical monitoring was used to visualize the dynamic electrochemical behaviors, unveiling the ionic liquid-mediated polybromide electrochemistry with a distinct chain length effect. A longer chain length possesses a stronger electrostatic interaction in the complexing product to effectively capture Br2. Operando results reveal the liquid nature of the reversibly electrogenerated polybromide microdroplets in the butyl4NBr-added redox system, which promoted the Br3-/Br- conversion kinetics and alleviated the self-discharge for improved battery performance. This work provides direct evidence and new insights into complexing electrochemistry for advancing Zn-Br2 batteries.

Enhanced flame retardancy and thermal insulation of epoxy resins composites incorporated with ammonium polyphosphate and ionic liquids loaded CuO-ZnO hollow spheres

Epoxy resin, as a thermosetting polymer material with good performance, has been limited in application due to its high flammability. In this investigation, porous CuO-ZnO hollow spheres (CZHS) were prepared by a hydrothermal method. By incorporation with ionic liquids loaded CuO-ZnO hollow spheres (CZHS@Ils) and ammonium polyphosphate (APP) into epoxy resin (EP) matrix, a new composite flame retardant material, named as EP/7.5APP/1.5CZHS@ILs, was developed for improvement of their thermal insulation and flame retardancy. The thermal conductivity of EP/7.5APP/1.5CZHS@ILs was measured to be 0.0197 W m −1 K −1, which is lesser than that of APP incorporated epoxy resin (EP/APP), demonstrating good thermal insulation capability. The flame retardancy were assessed using the limiting oxygen index (LOI) test, the Vertical flame testing (UL-94) test, and the cone calorimeter (CC) test. The results obtained from LOI test show that the EP/7.5APP/1.5CZHS@ILs has good flame retardancy with a LOI value of up to 28, better than that of pure EP which has a LOI value of 19.2. Moreover, a V-0 level of the EP/7.5APP/1.5CZHS@ILs was observed from the UL-94 test. The peak heat release rate (PHRR) was reduced to 257.9 kW m−2, which is 74.8 % lower than that of the pure EP. Such results are attributed to the synergy effect of CZHS@ILs and APP which offers the epoxy resin excellent flame retardancy. Taking advantages of the excellent thermal insulation, flame retardancy and better mechanical properties, the as-resulted EP/7.5APP/1.5CZHS@ILs may hold great potential for future thermal insulation and flame-retardant applications of energy saving building.

Ionic liquid–based aqueous biphasic system as an alternative tool for enhanced bacterial DNA extraction

BackgroundDeveloping an alternative and benign method for DNA extraction is imperative due to the high cost and potential harms associated with conventional techniques. Investigation of Ionic liquid (IL) as a solvent for DNA storage and stability revealed the ability of IL to assist DNA processes. IL–based aqueous biphasic system emerges as a comprehensive extraction platform capitalizing on the task–specificity of ILs and the wide applicability of ABS for biomolecule extractions. Therefore, it is beneficial to optimize an IL–based ABS specifically for DNA extraction, taking into account the fundamental interactions between the IL and DNA. ResultsThe primary objective was to design ABS consisting of Ammonium based ILs, and Potassium phosphate buffer as the salting–out agent for the partitioning of salmon sperm DNA. The analysis focused on optimizing biocompatible anions for the extraction. Moreover, the stability of the DNA in the IL rich phases was analysed to validate the method. The proposed process was then employed for extracting plasmid DNA from bacteria, demonstrating results comparable to those obtained with a commercially available kit. Further validation using agarose gel electrophoresis and transformation of the extracted DNA into E.coli were conducted, producing promising outcomes. Although there is room for improvement in terms of recovery of DNA and reusability of ABS, the described approach is comparable with the conventional one while being cost–effective, and showcases a noticeable and convincing link to eco–friendly processes. SignificanceThere is limited literature on IL–based ABS for DNA extraction, and the existing studies predominantly concentrate on systems derived from Cholinium ILs. However, their high hydrophilicity limits the choice of the second–phase forming component to polymers for the formation of ABS. Ammonium ILs efficiently form biphasic systems with various available salting–out agents, and biocompatible anions are introduced to mitigate the toxicity of the ILs.

Effect of alkyl chain length on the thermal properties and toxicity of n-alkyl-ammonium nitrate ionic liquids (n = 2, 3, 4, 5, 6, 8) for energy applications

AbstractThe most currently used ionic liquids (ILs) are protic ionic liquids (PILs), subject to extensive investigation regarding their physical properties. These compounds along with their mixtures with other substances such as salts and solvents, serve as electrolytes in next generation electrochemical smart devices, and emerge as viable candidates to replace conventional Heat Transfer Fluids (HTFs) in various energy applications. Despite the extensive number of studies, important information about this kind of compounds is still unknown, such as the effect of alkyl chain length on thermal and thermophysical properties, as well as toxicity. This work, extending previous studies of our group, summarizes the liquid range, heat capacity and acute toxicity level of six ammonium ILs: specifically, n-alkyl-ammonium nitrate ILs with increasing alkyl chain length (n = 2, 3, 4, 5, 6, 8). For this study, the synthesis of the three ILs with the longest alkyl chain was performed, along with DSC, TGA and toxicity measurements. It was observed that an increase in alkyl chain length resulted in a decrease in short-term thermal stability and an increase in melting temperature, indicating a reduction in the liquid range. A compensation effect between enthalpy and entropy of melting was observed for the studied chain lengths. The isobaric specific and molar heat capacities increase with temperature for all the compounds studied here, and good correlations were obtained between molar heat capacity and the number of carbon atoms in the alkyl chain for every temperature. Finally, most of the ILs are non-toxic, although toxicity increases with alkyl chain length.

Fabrication of Core–Shell Nanohybrid-Structured Hydrogel Sensors with Desirable Mechanical and Antibacterial Properties by Quaternary Ammonium Ionic Liquids with Different Chain Lengths

Fabrication of Core–Shell Nanohybrid-Structured Hydrogel Sensors with Desirable Mechanical and Antibacterial Properties by Quaternary Ammonium Ionic Liquids with Different Chain Lengths

The efficacy of ammonium ionic liquid to inhibit the parasitic process for Al-air battery

The main objective of this study is to determine how effectively the ammonium ionic liquid (tris(2 hydroxyethyl) methyl ammonium methylsulfate [THMA]+[MS]− works in minimizing parasitic reactions during Al-air battery discharge. The findings obtained indicate that the use of [THMA]+[MS]− reduced the rate of hydrogen gas output during the immersion of Al substrate in the 4.0 M KOH solution. The effectiveness of the ammonium ionic liquid under comparable conditions is confirmed using the linear cathodic polarization method. The addition of [THMA]+[MS]− to a pure 4.0 KOH solution improved the anodic efficiency and capacity density of the battery. Aside from being a novel study for [THMA]+[MS]− as electrolyte battery additives, theoretical research were employed to analyze the mechanism and data interpretation. Molecular dynamics (MD) simulations of inhibitor-Al interactions performed with Forcite's Materials Studio module add to the data that ammonium ionic [THMA]+[MS]− may suppress the parasite process. SEM, EDX, and X-ray Photoelectron Spectrometer (XPS) tests for Al electrodes under different circumstances following battery discharge at 20 mA cm−2 support the performance of [THMA]+[MS]−.

Stable diesel microemulsion using diammonium ionic liquids and their effects on fuel properties, particle size characteristics and combustion calculations

Ecofriendly and stable Fuel Microemulsions based on renewable components were prepared through solubilizing ethanol in diesel and waste cooking oil blend (4:1). New diquaternary ammonium ionic liquids (3a & 3b) were synthesized through a quaternization reaction of the synthesized dihaloester with diethyl ethanolamine tridecantrioate and triethyl amine tridecantrioate, respectively. The chemical structures were elucidated by NMR spectroscopy. It was observed from DLS analyses that the ethanol particles in all samples have sizes between 4.77 to 11.22 nm. The distribution becomes narrower with the decrease in the ionic liquid concentrations. The fuel properties fall within the ASTM D975 acceptable specifications and are close to the neat diesel properties. The Cetane index were 53 and 53.5, heating values were 38.5 and 38.5 MJ/kg, viscosities were 2.91 and 2.98 mm2/s, densities were 8.26 and 8.29 g/mL and flash points were 49 °C and 48 °C for 3a1 and 3b1 microemulsions, respectively. The particle sizes of samples were examined by DLS for 160 days and they were significantly stable. The amount of ethanol solubilized increases with the increase in the amount of the synthesized ionic liquids and cosurfactant. The combustion calculations pointed out that the microemulsions 3a1 and 3b1 need 13.07 kg air/kg fuel and 12.79 kg air/kg fuel, respectively, which are less than the air required to combust the pure diesel. According to theoretical combustion, using ionic liquids saves the air consumption required for combustion and reduces the quantities of combustion products. The prepared microemulsions were successfully used as a diesel substitute due to their improved combustion properties than pure diesel and low pollution levels.

Tribological performance of fatty acid ammonium ionic liquids as anti-wear additives in water-based fluids

In this study, we synthesized eight water-soluble ionic liquids (ILs) and investigated their tribological performance as additives in water-diethylene glycol (WDG) base fluids. The results of the tribological test suggested that these ILs additives demonstrate promising capabilities in friction reduction and anti-wear for water lubricated contacts. The ILs with the longest carboxylic chain length, namely C10MIPA and C10DIPA in this work, displayed superior tribological performances. Observations on the abraded surfaces showed that the IL forms a monolayer adsorption through self-assembly, and upon rubbing it creates a continuous and stable tribo-film with an uneven thickness of 30–60 nm through tribo-chemical reactions. The tribo-film mainly consists of iron oxides. The proposed lubrication mechanisms include adsorbed film and formed tribo-films, which work effectively to reduce the shear stress and thus sliding friction.

Enhanced proton conductivity of sulfonated poly(ether ether ketone) membranes by constructing cation‐π through doping ammonium ionic liquid and graphene oxide

AbstractIn this paper, sulfonic acid functionalized benzothiazole ionic liquid ([(CH2)3SO3HBth] [H2PO4]) and graphene oxide were combined together through the cation‐π. The sulfonated poly (ether ether ketone) was doped with ionic liquid‐modified GO (IL‐GO) to prepare the SPEEK/IL‐GO composite membrane through the solution casting method. The SO3H and benzothiazole rings act as both proton acceptors and proton donors during proton transport and can replace the role of water in medium‐ and high‐temperature environments, increasing the proton transport sites to a certain extent and increasing the proton conductivity of the SPEEK/IL‐GO composite membrane. The proton conductivity of the SPEEK/IL‐GO‐2 composite membrane achieved an 18.02 mS/cm at 120°C, which is 2.43 times higher than that of the pristine SPEEK membrane. This paper provided a method for increasing proton conductivity and limiting IL loss of the SPEEK membrane.Highlights [(CH2)3SO3HBth][H2PO4] and graphene oxide were combined through cation‐π. The benzothiazole ring and SO3H form acid–base pairs. The proton conductivity of SPEEK/IL‐GO‐2 membrane achieved 18.02 mS/cm.

MCM-41 supported quaternary ammonium ionic liquids as an effective heterogeneous catalyst for CO2 cycloaddition reaction

MCM-41 supported quaternary ammonium ionic liquids as an effective heterogeneous catalyst for CO2 cycloaddition reaction

Electrical Conductivity and Thermodynamics of Ion Association of Ammonium Ionic Liquids in Acetone

The electrical conductivity of a number of tetraalkylammonium ionic liquids with tetrafluoroborate anion has been studied in acetone in the temperature range 298–313 K. Based on the obtained conductometric data for the compounds under study, the Lee–Wheaton method has been used to calculate the ion association constants (Ka), limiting molar electrical conductivities (λ0), and Gibbs association energy (ΔG0) in solutions. From the temperature dependence of equivalent electrical conductivity, the values of association enthalpy (ΔH0) and entropy (ΔS0) have been calculated. For all studied compounds, the Walden–Pisarzhevsky product has been calculated. Conclusions are drawn about the influence of the structure of the studied ionic liquids on the thermodynamic parameters of association in acetone solutions.

Electrical Conductivity and Thermodynamics of Ion Association of Ammonium Ionic Liquids in Acetone

Electrical Conductivity and Thermodynamics of Ion Association of Ammonium Ionic Liquids in Acetone

A review of ionic liquids: Recent synthetic advances and oilfield applications

BackgroundIonic liquids have received a lot of interest in recent years from scientists and academics due to their distinctive qualities, including low vapor pressure, low toxicity, high thermal stability, and recyclability. Ionic liquids have become a more sustainable substitute for volatile organic solvents. MethodsIonic liquids can be synthesized with tailored properties by combining specific cationic and anionic components. Because of their distinct physiochemical characteristics and advantages, ionic liquids were used in different industrial processes such as organic/inorganic synthesis, biomass conversion, desulfurization, catalysis, electrochemistry, spectroscopy, and energy storage. FindingsThe primary goal of the current review is to outline the numerous synthetic routes for various classes of ionic liquids such as imidazolium, phosphonium, sulfonium, pyridinium, ammonium, pyrazolium, triazolium, and protic ionic liquids. Ionic liquids have drawn interest for a variety of oilfield applications because of their stability under challenging reservoir conditions, tunability, and low toxicity. This review primarily concentrates on the numerous oilfield applications including demulsification, drilling, heavy oil recovery, and CO2 capture. This review also covers the challenges and drawbacks associated with the synthesis and applications of ionic liquids and provides a reasonable solution and potential ideas to address the challenges.

Analysis of the pyrolysis process of ionic liquid-based flame retardant rigid polyurethane foam

In this study, flame retardant polyurethane rigid foam was prepared by incorporating 15 wt% ammonium polyphosphate (APP) and ionic liquid (1-butyl-2,3-dimethylimidazolium tetrafluoroborate, abbreviated as B4F). The flame retardant and thermal stability of the material were evaluated using vertical combustion (UL-94), limiting oxygen index (LOI), cone calorimeter (CONE), and thermogravimetric analyzer (TG) tests. Additionally, scanning electron microscopy (SEM), Raman spectroscopy (Raman), and X-ray photoelectron spectroscopy (XPS) were utilized to explore the flame retardancy mechanism in the carbon layer after combustion. The experimental results showed that the addition of 1 wt%B4F and 14 wt% APP to the polyurethane (RPUF/14APP/1B4F) significantly improved the vertical combustion test, upgrading it from the V-1 level to the V-0 level. This improvement was attributed to the increased degree of graphitization of the material, as evidenced by the reduced ratio of amorphous carbon to graphitic carbon (ID/IG) from 2.68 to 1.38. XPS analysis revealed that RPUF/14APP/1B4F exhibited a higher C/O ratio in the residual carbon (3.03) compared to RPUF/15APP (1.84), indicating that B4F effectively enhanced the antioxidant properties of the flame-retardant materials. Under the air atmosphere, RPUF/14APP/1B4F demonstrated an increased char formation at 800 °C (21.24 %), which was 71.01 % higher than RPUF/15APP. The interaction between B4F and APP led to the formation of a more stable char layer structure in polyurethane, further enhancing its flame retardancy. In conclusion, the RPUF/14APP/1B4F demonstrated a synergistic flame retardancy effect and enhanced thermal stability. The addition of B4F improved the graphitization degree of the material and increased the C/O ratio in the residual carbon, enhancing the antioxidant properties of the system. Moreover, the interaction between B4F and APP promoted the formation of a more stable char layer, effectively improving the flame retardant properties of the polyurethane. These findings provide valuable insights for the development of advanced flame retardant polyurethane materials with improved fire safety in various applications.

Modelling mixtures of ammonium and pyridinium-based ionic liquids and carbon dioxide with the Cubic Plus Association Equation of state

Modelling mixtures of ammonium and pyridinium-based ionic liquids and carbon dioxide with the Cubic Plus Association Equation of state

Role of ammonium ionic liquid and Pd nanoparticles in cavitation-based graphite decontamination and recycling process

Sonochemical recovery of radioactive contaminants from nuclear graphite has been demonstrated to be quite invaluable in recent studies. However, graphite is a soft material and is prone to erosion and wear. This restricts the recycle of graphite cleaned using ultrasound beyond a few decontamination cycles. Hence, it is an imperative to prevent the surface erosion of graphite in the sonic field. The current work studies the efficacy of ultrasound in decontaminating ceria contaminated graphite coupons using a cocktail of acids (0.25 M HNO3 − 1 M HCOOH − 0.2 M [N2H5][NO3]). Based on the superlative effects of ionic liquids in lubrication and erosion prevention, the effect of adding ionic liquid stabilized Pd nanoparticles to the leachate was also studied. It was observed that the Trioctylmethyl ammonium chloride (TOMAC) ionic liquid prevented the generation of the carbon residue due to a protective viscous layer formation reducing the mechanical effects of cavitation on graphite surface. It also helped in maintaining the porosity change in graphite microstructure around 5% after 15 cycles of decontamination. TOMAC also proved to offer better surface protection on graphite compared to imidazolium-based ILs, based on the change in compressive strength and porosity in different ionic liquids. The palladium nanoparticles, on the other hand, helped in reductive dissolution of ceria layer by acting as a reducing agent due to its lower reduction potential compared to cerium. With the surge in demand of graphite worldwide, a non-destructive decontamination process for graphite with no secondary waste generation is the need of the hour. This study is an attempt in that direction.

Comparative study on the physicochemical properties of N-SO3H functionalized ammonium and imidazolium ionic liquids

Twelve N-SO3H functionalised ammonium and imidazolium based Brønsted acidic ionic liquids were synthesised by varying four anions (Cl-, CF3COO-, BF4- and OTf-). They were characterised using various spectroscopic techniques. A detailed study on Brønsted acidity, thermal stability, conductivity, density, polarity, and electrochemical window of the ionic liquids (ILs) was carried out to analyse the effects of different cations and anions. The conductivity of these ILs in molecular solvents (MeOH, MeCN and acetone) were measured at a particular mole fraction (XIL = 0.001) of the ILs and the results were correlated with Kamlet-Taft solvatochromic parameters (ETN, α, β) of the solvents. Their Brønsted acidity order was determined using the Hammett plots. The polar nature of synthesized ionic liquids was studied by taking fluorescence emission spectrum of pyrene as a probe molecule in two illustrative 2-ethyl-1,3-disulfoimidazolium ionic liquids. The electrochemical stabilities of twelve ILs in the same molecular solvents were determined by Cyclic Voltammetry. The results revealed highest electrochemical stability window for the imidazolium ILs in acetone. Among the four types of anions, the ionic liquids of CF3COO- and Cl- anions were found to be thermally stable up to 250–260 °C as compared to the ionic liquids of BF4- and OTf- anions.

Wettability and Surface Tension of Imidazolium, Ammonium, and Phosphonium Bis(fluorosulfonyl)amide Ionic Liquids: Comparison between Pentyl, Ethoxyethyl, and Ethylthioethyl Groups.

This study particularly compares the surface tensions and contact angles for molten bis(fluorosulfonyl)amide salts of imidazolium, ammonium, and phosphonium cations with the pentyl, ethoxyethyl, or ethylthioethyl group. The examined substrate plates for contact angle measurements include silicate glass, platinum, copper, graphene, and polytetrafluoroethylene (PTFE). In addition, quantum chemistry calculations were performed to obtain the optimized structures of the cations and anions of the ionic liquids (ILs) that were studied here along with some typical anions and their dipole moments, mean polarizabilities, and charge distributions. All ILs showed the same order of contact angles with respect to the substrates: PTFE > graphene ≈ copper ≈ platinum > silicate glass. By comparing the three functional groups, i.e., pentyl, ethoxyethyl, and ethylthioethyl, the ILs with the ethylthioethyl group featured a higher work of adhesion than the respective ILs with the pentyl or ethoxyethyl group. The values of the surface tensions of the ILs followed the same trend for the three functional groups. Based on the Fowkes theory, it was found that the larger surface tensions of the ILs with the ethylthioethyl group compared with pentyl and ethoxyethyl groups were because of the increase in both dispersive and nondispersive components. The quantum chemistry calculations of the ions showed a larger dipole moment and mean polarizability for the cations with the ethylthioethyl group as compared with the pentyl and ethoxyethyl groups. This is consistent with the analysis results of the surface tensions based on the Fowkes theory. By comparing other anions, the dispersive component of the surface tension of the ILs with bis(fluorosulfonyl)amide was large, which is attributed to the small dipole moment of the anion.

Investigation of physical and electrochemical behaviour of N-sulfonic acid functionalized cyclic-ammonium based Brӧnsted acidic ionic liquids in molecular solvents

Two types of six Brӧnsted acidic ionic liquids of N-SO3H tethered cyclic ammonium cations (five, six and seven membered) with four anions namely [AcO]−, [HSO4]−, [BF4]−, [PF6]− were synthesized to evaluate their physical and electrochemical behavior in polar solvents (water, MeOH & CH3CN) using conductivity and Cyclic Voltammetry techniques. Their comparative Brönsted acidic orders were determined using UV–visible Hammett plots. Except the ionic liquid of [PF6]− anion with N,N-disulfopiperidinium cation, the thermal stabilities of other ionic liquids found within 230–250 °C. Solvent dependent aggregative nature was observed in polar solvents for the ionic liquids at a particular temperature and concentration. Their aggregative properties were also evidenced by comparison of experimental and computed chemical shift values of additional acidic protons of 1H NMR spectra. Kamlet-Taft solvatochromic parameters of molecular solvents (ETN, α, β) were correlated with their observed conductivities. Piperidinium ionic liquids showed wider electrochemical windows (2.99 V to 2.55 V) in acetonitrile as compared to other cyclic ammonium ionic liquids in polar solvents.

Quaternary ammonium ionic liquids based on -SO3H with different alkyl chain lengths as electrolytes for fuel cells and the mechanism for proton transfer in ionic liquid

N, N, N-trimethyl propylsulphonate ammonium hydrosulfate (NC3SO3HHSO4) and N, N, N-trimethyl butyl sulphonate ammonium hydrosulfate (NC4SO3HHSO4) have been synthesized as electrolytes for the fuel cell. The results indicate that the single cell with NC3SO3HHSO4 exhibits a higher maximum power density (MPD) compared to that of the cell with NC4SO3HHSO4. The MPD achieved using NC3SO3HHSO4 and NC4SO3HHSO4 at 50°C were 48.5 mW·cm−2 and 38.2 mW·cm−2, respectively. The diffusion of ions becomes rapid for ionic liquids (ILs) due to their low viscosity, high conductivity, and chemical structure. Furthermore, quantum chemistry calculations provide detailed insights that elucidate the mechanisms underlying the improvement of cell performance. The proton transfer mechanisms in NC3SO3HHSO4 and NC4SO3HHSO4 are further investigated, including the proton transfer between H2SO4 and HSO4−, the proton transfer between cations and their corresponding neutral molecules, as well as the proton transfer between cations and anions. The cell performance improvement mainly depends on proton transfer between cations and their corresponding neutral molecules. The activation energy barriers for the NC3SO3H+-NC3SO3 complex, between the initial structures and the transition state, and between the final structures and the transition state, are 0.67 kcal·mol−1 and 1.55 kcal·mol−1, respectively. However, proton transfer from an NC4SO3H+ to an NC4SO3 does not occur. The difficulty in proton transfer may be attributed to the steric hindrance effect of cations. Therefore, it can be inferred that the steric hindrance effect of cations significantly impacts the mechanism of proton transfer.