Chloride Ionic Liquid Research Articles

Use of aqueous two-phase systems formed by Triton X and choline chloride for extraction of organic and inorganic arsenic

The use of aqueous two-phase systems (ATPSs) for the extraction/speciation of arsenic has received attention in recent years. However, only ATPSs formed by polymer and salt have been used, hindering a global understanding of the mechanism of partitioning of the metalloid and limiting the development of strategies for arsenic speciation in these systems. Therefore, it is important to study the partitioning of different arsenic species in new and more environmentally friendly ATPSs, such as those formed by ionic liquids based on the choline cation. In this work, ATPSs formed by Triton X nonionic surfactant, choline chloride ionic liquid, and water were used to study the partitioning of three arsenic species (As(III), As(V), and dimethylarsinic acid (DMA)), in the absence and presence of the extracting agent ammonium pyrrolidine dithiocarbamate (APDC). Evaluation was made of the effects of the parameters extraction time, pH, tie-line length, extractant concentration, and nature of the surfactant on the distribution of the arsenic species in the ATPS. In the absence of the extracting agent, all the arsenic species were mainly transferred to the choline chloride-rich phase, with maximum extraction percentages of 69.02, 92.99, and 90.05% for As(III), As(V), and DMA, respectively. In the presence of APDC, the As(V) and DMA species mainly remained in the choline chloride-rich phase, while the As(III) was transferred to the surfactant-rich phase, with the best removal to this phase achieved using the ATPS formed by TX-165 + choline chloride + water, at pH 1.00 and with an APDC:arsenic molar ratio of 25. Compared to ATPSs formed by polymer and salt, the ATPSs formed by Triton X and choline chloride required up to nineteen times smaller amounts of APDC for quantitative extraction of As(III) to the phase low in electrolyte. Thus, the results demonstrated the excellent potential of the Triton X + choline chloride + water systems for the extraction, preconcentration, and speciation of arsenic, with the advantage that the components used to form the ATPSs make the technique more environmentally friendly.

Computational NMR Study of Ion Pairing of 1-Decyl-3-methyl-imidazolium Chloride in Molecular Solvents.

The 1H NMR spectra of 10–5 mole fraction solutions of 1-decyl-3-methyl-imidazolium chloride ionic liquid in water, acetonitrile, and dichloromethane have been measured. The chemical shift of the proton at position 2 in the imidazolium ring of 1-decyl-3-methyl-imidazolium (H2) is rather different for all three samples, reflecting the shifting equilibrium between the contact pairs and free fully solvated ions. Classical molecular dynamics simulations of the 1-decyl-3-methyl-imidazolium chloride contact ion pair as well as of free ions in water, acetonitrile, and dichloromethane have been conducted, and the quantum mechanics/molecular mechanics methods have been applied to predict NMR chemical shifts for the H2 proton. The chemical shift of the H2 proton was found to be primarily modulated by hydrogen bonding with the chloride anion, while the influence of the solvents—though differing in polarity and capabilities for hydrogen bonding—is less important. By comparing experimental and computational results, we deduce that complete disruption of the ionic liquid into free ions takes place in an aqueous solution. Around 23% of contact ion pairs were found to persist in acetonitrile. Ion-pair breaking into free ions was predicted not to occur in dichloromethane.

Experimental and DFT studies on structure, spectroscopic and thermal properties of N-Methyl-N,N,N-trioctylammonium chloride ionic liquid

The [Aliquat+][Cl−] ionic liquid (IL) has been structural and vibrationally characterized combining experimental FT-IR, FT-Raman and 1H- and 13C-NMR spectroscopies with theoretical studies based on the hybrid B3LYP/6-31G* method. The theoretical determination of structure of IL in gas phase and aqueous solution by using that level of theory shows three ionic C-H···Cl bonds, as supported by atomic Merz-Kollman (MK) charges, bond orders, natural bond orbital (NBO) and atoms in molecules (AIM) calculations. Hence, a monodentate coordination between the [Aliquat+] cation and Cl anion has been proposed for IL because only one of three ionic C-H···Cl bonds presents higher energy and lower distance. The optimized structure confirmed by NMR measurements has allowed the assignments of 237 normal vibration modes to the bands observed in the infrared and Raman spectra with the aid of scaled quantum mechanical force field (SQMFF) methodology and the normal internal coordinates. The effect of Cl in the IL is the shifting of vibration modes corresponding to the CH2 and CH3 groups, as compared with the cation. The mapped MEP surface evidence a strong concentration of charges around the chloride anion compatible with nucleophilic sites in these regions while the frontier orbital analyses suggest that IL is most reactive than the cation probably due to the low values of both global electrophilicity and nucleophilicity indexes. The thermal stability shows that [Aliquat+][Cl−] start to decompose just above 200°C. Comparisons between [Aliquat+][Cl−] and [Aliquat+][NTf2−] ILs show that the IL containing chloride is most reactive than the other one while [Aliquat+] [NTf2−] is thermally more stable than [Aliquat+][Cl−]. These results suggest that the properties of an IL containing the [Aliquat+] cation are strongly dependent of anion. In addition, the scaled force constants for the [Aliquat+][Cl−] IL are also calculated and compared with the reported for the cation. The Cl anion modifies in notable form the properties of cation.

FUNCTIONALIZATION OF CELLULOSE AND CHITOSAN IN IONIC LIQUIDS

Chemistry of cellulose in ionic liquids has been briefly reviewed and, accordingly, the phthalation of chitosan in these ionic solvents has been investigated. Chitosan (K) has been reacted at 100 °C for 4 hours with phthalic anhydride (PA) in ionic liquids 1-butyl-3-methylimidazolium acetate (BMIMAc) and 1-butyl-3-methylimidazolium chloride (BMIMCl) in the presence of bases, pyridine and 1,4-diazobicyclo[2.2.2] octane (DABCO), or the phthalation has been catalyzed by N-bromosuccinimide (NBS). Depending on the nature of the reaction components, the samples were prepared with molar ratios of PA to anhydroglucose unit (PA:K) from 3:1 to 10:1, including molar ratios of bases or catalyst to chitosan, ranging also from 3:1 to 10:1. All the reaction products were soluble in dimethyl sulfoxide and dimethylformamide. Both functional groups of chitosan units, -OH and -NH2 , reacted, resulting in FTIR confirmed products containing esters, amide, and imide functional groups. Heating the isolated phthalated chitosan products to 200 °C led to cyclization with the formation of imide groups and elimination of water. When bases controlled the reactions, the highest degrees of substitution of DABCO product (DS = 0.80) was slightly higher than the highest DC of the reaction products obtained in the presence of pyridine (DS = 0.77). However, the presence of the Nbromosuccinimide catalyst in the system led to an increase of the degree of substitution of the functional groups of chitosan (DS = 1.75), compared with that listed above for the products resulted when the reactions were carried out in the presence of bases. The thermal stability of the chitosan derivatives obtained in the presence of a base depended primarily upon the nature of the counter ion of the ionic liquid. When the reaction was conducted in the acetate ionic liquid BMIMAc, the phthalated chitosan exhibited a lower thermal stability than that of chitosan, while when the chloride ionic liquid BMIMCl was used as solvent, the thermal stability of the phthalated chitosan increased, indicating an interference of the ionic solvents in the mechanisms of reactions. Nevertheless, the thermal behavior of the phthalated products obtained in reactions catalyzed by NBS may be correlated with the increasing degrees of substitution achieved with increased catalyst concentrations: a higher DS resulted in a higher weight loss at higher temperatures.

Ultratough and recoverable ionogels based on multiple interpolymer hydrogen bonding as durable electrolytes for flexible solid‐state supercapacitor

AbstractThe emerging application of ionogels in flexible devices require it enough durable under repeated mechanical deformation while maintaining their superior electrochemical properties. In this work, ultratough and recoverable ionogels, where ionic liquids are confined in chemically and interpolymer hydrogen‐bonding hybrid crosslinked network, were fabricated by in situ copolymerization of acrylic acid and 1‐vinylimidazole monomer within 1‐buty‐3‐methylimidazolium chloride ionic liquid. The reversible hydrogen bonds between imidazole and carboxylic acid groups of polymer chains in the network work as reversible “sacrificial bonds” to toughen ionogel, which makes the ionogels tough (tensile strength 1.62 MPa, toughness 8.7 MJ m−3), stretchable (elongation at break 1090%), and recoverable (91% recovery resting for 30 min, at 534 kPa stress and 500% strain). Moreover, the hydrogen‐bonded ionogels exhibit high ionic conductivity of 2.3 S m−1 at 80°C to 3.2 S m−1 at 150°C. Furthermore, the ionogel‐based flexible electrical double‐layer capacitor can be operated up to 1.5 V with a capacitance of 341.47 F g−1 at 0.5 A·g−1 and exhibits excellent capacitance retention after 1000 cycles as well as superior electrochemical performance over a wide range of temperature. This work provides new insights into the synthesis of tough and recoverable ionogels for high‐performance flexible supercapacitors.

Ionic Liquid and f‐MWCNTs Fabricated Glassy Carbon Electrode for Determination of Amygdalin in Apple Seeds

AbstractThis work proposes a novel electrochemical sensor based on functionalised multiwalled carbon nanotubes (f‐MWCNTs), zinc oxide nanoparticles (ZnONPs), and (methyltrioctylammonium chloride ionic liquid (IL)) fabricated glassy carbon electrode (GCE), for the determination of amygdalin (AMY) in apple seeds. X‐ray diffraction (XRD), Brunauer‐Emmett‐Teller (BET), Fourier‐transform infrared spectroscopy (FT‐IR), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) as well as electrochemical impedance spectroscopy (EIS) techniques were used to characterize the synthesized ZnONPs and its nanocomposite. EIS and differential Pulse Voltammetry (DPV) was utilized to investigate the electrochemical behavior of AMY on the IL‐ZnONPs‐f‐MWCNTs nanocomposite modified GCE. The linear range response is obtained from 0.012–6 μM for AMY determination under optimized experimental conditions, and the limit of detection (LOD) values were found to be 0.012 μM. The novel method developed was successfully used to determine AMY in spiked apple seed samples with satisfactory results.

Experimental and modeling study of CO2 separation by modified Pebax 1657 TFC membranes

Ionic liquid modified Pebax 1657 thin-film composite (TFC) membranes were synthesized on different porous supports for improved separation of CO2 from CH4 and N2. XRD, SEM, FTIR, TGA, DFT, and BJH tests were utilized for the characterization of TFC membranes and supports. The incorporation of 1,3-Di-n-butyl-2-methylimidazolium chloride ionic liquid into the Pebax 1657 solution led to better compatibility between selective layer and support. The results of gas permeation tests showed an enhanced CO2/CH4 and CO2/N2 selectivity for most of the ionic liquid modified TFC membranes. To derive a predictive model for the permeability of gases in TFC membranes, correction factors (β) for fractional free volumes of TFC membranes were linearly correlated against correction factors (α) for porosity and tortuosity of the substrate in the dusty gas model using CO2 experimental permeance data at 20, 60, 100 and 140 °C. The resulting modified model showed remarkable effectiveness in the prediction of permeability of CH4 and N2 in the TFC membrane at investigated temperatures. The comparison of model predictive performance with previous models showed the supremacy of the new model in terms of average absolute relative errors (AARE) and the standard deviation of relative errors (σ).

Synthesis, Characterization and Pyrolysis Kinetics of Chitosan-N-Phenylacetamide in an Ionic Liquid 1-Butyl-3-Methylimidazolium Chloride

This study intends to synthesis novel compound phenolic chitosan-based via reaction of chitosan with 2-Chloro-N-phenylacetamide in 1-butyl-3-methylimidazolium chloride ionic liquid in the presence of pyridine at 80 °C for 4 h. The alterations in the chemical structure and morphology of the chitosan-N-phenylacetamide biopolymer were verified using IR spectroscopy, XRD, and SEM analyses. Chitosan and Chitosan-N-phenyacetamide were subjected to thermo-gravimetric analysis under an inert atmosphere in the temperature range of room temperature - 600 °C at a heating rate of 20 °C.min-1. The kinetic parameters were determined by the Coats-Redfern method. The corresponding kinetic parameters of the main degradation stages were also determined. The energy required for the degradation of pure chitosan was lower than that of chitosan-N-phenylacetamide in the first region of thermal degradation where the main pyrolysis reaction took place, and the largest weight loss occurred. Energy values in this region are running from 40.25 to 151.07 kJ/mol and 58.45 to 210.99 kJ/mol, respectively. The most probable reaction functions have thus been determined for these two stages by Coats-Redfern and Criado method, leading to greatly improved calculation performance over the entire conversion range. The pyrolysis reaction models of both pure chitosan and chitosan-N-phenylacetamide are described by the reaction, second-order F2.

Effects of AlCl3–1-ethyl-3-methylimidazolium chloride ionic liquid composition on transport properties

The paper presents a series of studies into the physicochemical properties such as density, viscosity and conductivity of acidic AlCl3–1-ethyl-3-methylimidazolium chloride ionic liquid (IL) at 30 °C. The ionic composition of the electrolyte is characterised by Raman spectroscopy. A study of the dependence of the ionic liquid specific conductivity on the concentration of AlCl3 at 0.50 ≤ xAl ≤ 0.67 (xAl is the mole fraction of AlCl3 in the melt) is undertaken. The plot of IL specific conductivity vs AlCl3 concentration smoothly decreases and does not contain any maxima across the investigated range of AlCl3 concentrations. A method of evaluating the transport numbers of chloroaluminate anions using only experimental data on conductivity, without performing additional experiments is proposed. A decrease in molar conductivity with the growth of AlCl3 concentration is found to be related to the decreasing total molar concentration of ions participating in charge carrying and the decreasing molar volume of the IL.

Conductivity of 1-Ethyl-3-Methylimidazolium Chloride (EMIC) and Aluminum Chloride (AlCl3) Ionic Liquids at Different Temperatures and AlCl3 Mole Fractions

In this work, the conductivity (k) of Lewis acidic ionic liquid (IL) comprising a melt of organic chloride and aluminum chloride (AlCl3) with different molar ratios of organic chlorides with AlCl3 in the temperature range of 70-110 °C are reported. The ILs prepared with three imidazolium-based organic chlorides such as EMIC, BMIC, and HMIC are studied. The molar ratios of 1:1.5, 1:1.8, and 1:2.0 are selected for the study to maintain the acidity of the ILs for possible metal electrodeposition applications. The electrochemical behavior of anion species in the three ILs is studied using electrochemical impedance spectroscopy (EIS) technique and obtained the precise and fast measurement of conductivity values. The measured k values of all the ILs followed the Arrhenius law. The activation energies of conduction determined by fitting the experimental conductivity data are in good agreement with the literature. The conductivity of ILs with lower alkyl group organic chlorides decreased with the higher mole fraction of AlCl3. In contrast, the conductivity of IL having a higher alkyl group organic chloride (HMIC) increased with the increasing mole fraction of AlCl3. Based on the thermodynamic calculations, the differences in conductivities are attributed to the anion concentration, the molecular structure, cation-anion interactions, and hydrogen bonds in the ILs.

Nucleation Study on Deposition of Aluminum from 1-Butyl-3-Methylimidazolium Chloride and Aluminum Chloride Ionic Liquid Electrolyte

In this study, aluminum is electrodeposited from ionic liquids comprising a melt of 1-butyl-3-methylimidazolium chloride (BMIC) and aluminum chloride (AlCl3) at the AlCl3 mole fraction of 0.667 (molar ratio of 1:2). The electrochemical behavior of chloroaluminate species in the ionic liquid is investigated by the chronoamperometry (CA) technique at different temperatures. The diffusion coefficients (D) of Al2Cl7 - species in such ionic liquid are calculated at various temperatures. The SEM was used to measure the grain size of the deposits. The calculated average radius of the Al deposit was 6.3 × 10-6, 5.2 × 10-6, and 4.3 × 10-6 m at 363 K, with an applied potential of 1.7, 1.75, and 1.8 V respectively. The calculated grain radius is comparable to the experimental data of electrodeposits. In addition, the rate of nucleation during the electrodeposition is also investigated.

Charge Transport and Dynamics in Imidazolium Chloroaluminate Ionic Liquids

Ion dynamics and charge transport in 1-alkyl-3-methylimidazolium chloroaluminate ionic liquids were investigated over broad temperature and frequency ranges by broadband dielectric spectroscopy and differential scanning calorimetry. The timescale of ion dynamics, as captured by the imaginary component of the complex dielectric modulus as well as the calorimetric glass transition temperature (Tg), is strongly composition-dependent, with the fastest dynamics, lowest Tg, and highest fragility observed for the Lewis acidic 67 mol% AlCl3 + 1-ethyl-3-methylimidazolium chloride composition. The DC ionic conductivity scales directly by the ion dynamics for all compositions indicating the primary effect of ion speciation is an alteration of the underlying ion mobility. The fragility (m) of the 67 mol% AlCl3 + 1-ethyl-3-methylimidazolium chloride ionic liquid, m=148, is among the highest reported fragilities for a glass-forming liquid.

Conductivity of 1-Ethyl-3-Methylimidazolium Chloride (EMIC) and Aluminum Chloride (AlCl3) Ionic Liquids at Different Temperatures and AlCl3 Mole Fractions

The conductivity (k) of ionic liquid (IL) comprising a melt of 1-ethyl-3-methylimidazolium chloride (EMIC) and aluminum chloride (AlCl3) with different AlCl3 mole fractions (XAl) and temperatures (343-383 K) are reported. XAl values of 0.6, 0.643, and 0.667 in EMIC-AlCl3 IL are selected to maintain the desired Lewis acidity. Precise and fast conductivity measurements and the behavior of anion species in IL are studied using electrochemical impedance spectroscopy (EIS). The measured k data followed the Arrhenius law using which the activation energies (E a) of conduction are determined. The conductivity of EMIC-AlCl3 IL decreased with the higher XAl. EMIC-AlCl3 with XAl=0.6 exhibited higher k (5.58 S m–1) at 383 K and lowest E a (4.25 KJ mol–1) among studied parameters. Based on the thermodynamic calculations, the differences in conductivities are attributed to the interplay of anion concentration, the molecular structure, cation-anion interactions, and hydrogen bonds in the IL.

(Invited) Electroplating of Bright Aluminum on the ABS Resin Substrate Covered with Cu Film in EmImCl-AlCl3 Ionic Liquid

To form bright and uniform Al electroplating film on Cu substrate, additive for electrolyte and support electrode were investigated in 1-ethyl-3-methylimidazolium chloride (EmImCl) and AlCl3 mixture ionic liquid. Al electroplating film from the ionic liquid containing the additive formed bright surface depend on rotation rate of ionic liquid electrolyte. By arranging the supporting electrodes, current concentration on the substrate was dispersed. An Al electroplated film having a uniform thickness was formed on the Cu substrate or ABS resin substrate covered with Cu plating. The electroplated film formed on the ABS substrate was anodized and showed pink, blue, and orange.

Electroanalytical Study of Active Species to Deposit Ti Alloy from 1-Butyl-3-Methylimidazolium Chloride-Aluminum Chloride Ionic Liquid

The electrochemical behavior of titanium-chloroaluminate anion species in Lewis acidic 1-butyl-3-methylimidazolium chloride (BMIC)-aluminum chloride (AlCl3) ionic liquid (IL) electrolyte with 0.667 AlCl3 mole fraction is investigated at 383K by cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP). The effect of scan rate on peak potential and peak current, constant current density, constant applied potential, and the electrolyte temperature are discussed. The redox reaction of the Ti2+/Ti0 deposition from titanium hepta-chloroaluminate ([Ti(Al2Cl7)4]2−) anions is a reversible process with a 2-electron transfer while that of Al3+/Al0 deposition from hepta-chloroaluminate ([Al2Cl7]−) anions is quasi-reversible with 3-electron transfer. The cyclic voltammograms indicated that the reduction of [Al2Cl7]− and [Ti(Al2Cl7)4]2− species to corresponding Al and Ti forms is a diffusion-controlled phenomenon. The diffusion coefficients (D) of the anion-species in BMIC-AlCl3 IL determined at 383 K using CV and CP methods are 9.74 × 10−10 m2 s−1 and 6.36 × 10−10 m2 s−1, respectively.

Nucleation Study on Deposition of Aluminum from 1-Butyl-3-Methylimidazolium Chloride and Aluminum Chloride Ionic Liquid Electrolyte

The aluminum is electrodeposited from an ionic liquid comprising a eutectic mixture of 1-butyl-3-methylimidazolium chloride (BMIC) and aluminum chloride (AlCl3) at the AlCl3 mole fraction of 0.667 (molar ratio of 1:2). The electrochemical behavior of chloroaluminate species in the ionic liquid (IL) is investigated by the chronoamperometry (CA) technique at different temperatures. The diffusion coefficients (D) of Al2Cl7 – anion species in BMIC-AlCl3 IL are calculated at various temperatures based on the chronoamperometric method. The calculated number density of nucleation of Al deposits are 0.7 × 1010, 1.0 × 1010, and 1.4 × 1010 m-2 at 363 K with the applied potentials of -1.7, -1.75, and -1.8 V versus Pt, respectively. The scanning electron microscopy (SEM) result indicated that the calculated data is comparable to the experimental electrodeposition data. In addition, the rate of nucleation was also investigated during the electrodeposition experiment.

The potential use of curcumin-β-cyclodextrin inclusion complex/chitosan-loaded cellulose sponges for the treatment of chronic wound

In this research, the cellulose sponges with curcumin-β-cyclodextrin inclusion complex (CMx) and chitosan (CS) were fabricated for use as wound dressings. 1-Allyl-3-methylimidazolium chloride (AMIMCl) ionic liquid as a green solvent was used for the fabrication of cellulose sponges. Due to the low aqueous solubility and low bioavailability of curcumin, cyclodextrins (CDs) were applied and complexed with curcumin to obtain CMx. In addition, CS was incorporated in the cellulose sponges to improve the antibacterial activity of sponges. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) analysis, morphological appearances, mechanical properties, water retention and weight loss, release behaviors, antibacterial activity, indirect cytotoxicity, cell attachment, and cell proliferation of the CMx/CS-loaded cellulose sponges were investigated. From the results, the cellulose sponges showed a porous structure. The incorporation of CMx and CS improved the mechanical properties when compared to the neat cellulose sponges. Moreover, the addition of CS into the cellulose sponges exhibited antibacterial activity against E. coli and S. aureus. Furthermore, the indirect cytotoxicity of the CMx/CS-loaded cellulose sponges was non-toxic and compatible with NCTC L929 and NHDF cells. Consequently, the CMx/CS-loaded cellulose sponges might be good candidates for use as wound dressing materials for the treatment of wound, especially chronic wound.

Electrochemical Performance of Graphitic Multi-walled Carbon Nanotubes with Different Aspect Ratios as Cathode Materials for Aluminum-ion Batteries.

Graphitic multi‐walled carbon nanotubes (MWCNTs) can function as high‐performance cathode materials for rechargeable Al‐ion batteries with well‐defined discharging plateaus and reasonable charge/discharge C‐rates. However, the main intercalation/deintercalation or adsorption/desorption path of AlCl4 − anions into or onto G‐MWCNTs has not been elucidated. Herein, we used battery cells comprised of G‐MWCNTs with different aspect ratios, Al metal, and AlCl3/1‐ethyl‐3‐methylimidazolium chloride ionic liquid as the cathode, anode, and electrolyte, respectively. The electrochemical performance of the Al||G‐MWCNT cell increased as the aspect ratio of the G‐MWCNT cathode increased (i. e., longer and thinner). The degree of defects of the G‐MWCNTs was similar (0.15–0.22); hence, the results confirm that the main and alternate paths for the AlCl4 − intercalation/de‐intercalation or adsorption/desorption into/from or onto/from the G‐MWCNT are the basal and edge planes, respectively. The step‐like structures of defects on the basal plane provide the main reaction site for AlCl4 − anions.

Theoretical and experimental studies of ionic liquid-urea mixtures on chitosan dissolution: Effect of cationic structure

Two imidazolium chloride ionic liquids (ILs) were mixed with urea for chitosan dissolution. Ionic liquids were [Amim]Cl and [Etmim]Cl (1-allyl-3-methyl-imidazolium chloride and 3-methyl-1-(ethylacetyl)imidazolium chloride, respectively). Physicochemical properties of neat ILs and IL-Urea solutions (including density, viscosity, conductivity, β value, π* value, and thermogravimetric analysis), were thoroughly investigated. Dissolution performance of chitosan in IL-Urea solutions was determined.Chitobiose (KET) as model chitosan structure, density functional theory (DFT) calculations were used to discuss the interactions between IL, urea, and chitobiose, and to clarify the different physicochemical properties of ILs, IL-Urea solutions. Also DFT simulation results were used for elucidating the influence of different cationic substituents and urea addition for chitosan dissolution.[Etmim]Cl showed higher density, viscosity, conductivity, β, and π* value than those of [Amim]Cl. These results revealed strong hydrogen bonds among [Etmim]Cl owing to the carboxylic acid ester group than allyl group of [Amim]Cl. Densities, viscosities, and π* values of IL-Urea solutions increased with increasing urea content. Conductivities and β values of IL-Urea solutions decreased with the increase of urea content at same temperature. The thermal stability of [Amim]Cl-Urea mixture increased when urea content increased from 10% to 30%, which was different from [Bmim]Cl-Urea melt. The thermal stability of [Etmim]Cl-Urea mixture was different to that of [Amim]Cl-Urea mixture.Urea was accommodated in ILs, forming hydrogen bonds with both the anion and cation in ILs, which changed the molecular interactions of ILs. The influence of different substituents in imidazolium ILs and urea addition on chitosan dissolution were analyzed using experimental determination and DFT calculations. Cationic substituents of imidazolium ILs play an extraordinary role in hydrogen bonds formation with chitobiose, so to strengthen chitosan dissolution. The information obtained would provide a guide for designing novel IL solvent systems for chitosan dissolution.

Electrochemical and Physical Properties of Imidazolium Chloride Ionic Liquids with Pyrrolidinium or Piperidinium Cation Addition and Their Application in Dual‐Ion Batteries

Herein, nonflammable ionic liquid (IL) electrolytes are prepared for dual‐ion batteries (DIBs) by mixing 1‐methyl‐1‐propylpyrrolidinium chloride (P13Cl) or 1‐butyl‐1‐methylpiperidinium chloride (PP14Cl) with 1,2‐dimethyl‐3‐propylimidazolium chloride (DMPICl)/aluminum chloride (AlCl3) to form mixed IL electrolytes. Then, viscosity, ionic conductivity, thermal stability, and electrochemical limits measurements are recorded to reveal the fundamental properties of the mixed IL electrolytes for DIBs, which are not reported previously. As compared with DMPICl/AlCl3 (=1 in mole ratio) electrolyte, using electrolyte with addition of P13Cl or PP14Cl (e.g., 0.63 mole to replace DMPICl), the DIB with graphite electrodes show better electrochemical stability. With the addition of 0.63 P13Cl, the Coulombic efficiency of the DIB reaches up to 96.7% (≈91% for DMPICl/AlCl3); however, specific capacity loss should be considered. In general, ideas for designing higher energy density electrochemical energy storage devices are provided.