Ethylene Glycol Deep Eutectic Solvent Research Articles

Recommended Practices for the Electrochemical Recovery of Cobalt from Lithium Cobalt Oxide: A Case Study of the Choline Chloride:Ethylene Glycol Deep Eutectic Solvent.

We recommend best practices for the recovery of cobalt from LiCoO2 (LCO) lithium-ion battery (LIB) cathodes by (i) leaching using green deep eutectic solvents (DES) and (ii) subsequent electrodeposition, through a case study of the choline chloride (ChCl):ethylene glycol (EG) DES. DES physical properties (conductivity, viscosity, and surface tension) were tailored by varying the composition between mole ratios of 1:2 and 1:5 (ChCl:EG). Examined along with leaching process parameters (temperature, duration), increasing the fraction of hydrogen bond donors (HBDs) decreased DES surface tension and enhanced leaching. Complete Co recovery was achieved using1:5 ChCl:EG DES at 160oC and 48 hours. Leaching temperatures >160oC are discouraged due to DES thermal degradation. The electrodeposition process was optimized for selective Co recovery with high faradaic efficiency. The leaching ability of the DES was antithetical to the stability of electrodeposition cell components and required operational parameter adjustment to minimize degradation. The optimized system (copper cathode and stainless-steel anode) employing 1:5 DES leachate exhibited a faradaic efficiency of ~80 %, specific Co recovery of ~0.8 mg hr-1 cm-1 at 50 oC and evidence of uniform deposition. DES surface tension is a key descriptor of metal recovery, and guidelines are presented to maximize selective Co recovery.

CO2 capture by imidazolium-based deep eutectic solvents: the effect of steric hindrance of N-heterocyclic carbenes.

CO2 capture by deep eutectic solvents (DESs) formed between 1,3-bis(isopropyl)imidazolium 1,2,4-triazolide ([IiPim][Triz]) and ethylene glycol (EG) is investigated in this study. [IiPim][Triz]-EG DESs exhibit a capacity of ∼1.0 mol CO2 per mol DES at 1.0 atm and 25 °C. Surprisingly, mechanistic results disclose that CO2 reacts with EG but does not bind with the C-2 site of the [IiPim]+ cation, which may be due to the high steric hindrance of the C-2 site of the N-heterocyclic carbene IiPim present in [IiPim][Triz]-EG DESs.

Application of Choline Chloride - Ethylene Glycol Deep Eutectic Solvent for the Extraction of Monocylclic Aromatic Hydrocarbon Contaminants from Soil

Abstract Monocyclic aromatic hydrocarbons like Benzene, toluene, ethylbenzene and xylene (BTEX) are among environmental pollutants that are considered among chemicals of concern. They are often found in industrial effluents, which when discharged into farmlands end up contaminating the soils. Such happenings warrant the remediation of the soil for environmental sustainability. Solvent extraction, prominent among the techniques employed for this remediation, is limited by the type of solvent used, as volatile organic solvents end up producing secondary pollutants. Various kinds of green solvents like Ionic Liquids (ILs) and Deep Eutectic Solvents (DESs) have been used in this technique as replacements for the conventional ones. In this study, DES made from choline chloride and ethylene glycol in the ratio of 1:2 was synthesized, characterized and used for the remediation of soils contaminated with monocyclic aromatic hydrocarbons (BTEX). Response surface methodology was employed to model and optimize the extraction process. Extraction efficiencies of 76.25, 79.04, 81.93 and 78.66% were obtained for benzene, toluene, ethylbenzene and xylene in a single stage extraction at optimum condition of 45 minutes, 0.841 and 440 rpm for extraction time, solvent mass fraction and mixing rate respectively. Further studies on the solvent regeneration and reuse were conducted. The findings showed that the solvent has capacity to perform effectively in two (2) successive extraction cycles without regeneration, and can undergo up to five (5) cycles upon regeneration without significant loss in its extracting ability. These studies show the possibility of remediating soils contaminated with BTEX using DES under mild extraction conditions.

Experimental and dynamic molecular study of zinc extraction from sphalerite concentrate in ternary deep eutectic solvent

The utilization of deep eutectic solvents (DESs) as a novel class of solvents in metal production offers a promising alternative to aqueous solutions due to their biocompatibility and non-aqueous nature. This study investigated the leaching of sphalerite concentrate using a ternary stable DES composed of choline chloride (ChCl), p-toluene sulfonic acid (PTSA), and ethylene glycol (EG) (at a molar ratio of 1:1:1). The effects of time, temperature, and milling time on zinc recovery were examined within specific ranges (20–1440 min, 40–100 °C, and 0–24 h, respectively). The study revealed the significant influence of time and temperature on zinc dissolution efficiency within ChCl:PTSA:EG. Higher temperatures and longer leaching times were found to improve efficiency substantially. The research emphasized the crucial role of milling time, demonstrating that longer durations enhanced zinc efficiency by introducing more defects on the sphalerite surface and reducing particle size. Under optimized conditions, including a temperature of 100 °C, 24 h of ball milling, and 1440 min of leaching, a zinc recovery of 99.7% was achieved. Infrared analysis confirmed the chemical stability of the solvents during the leaching process. The sphalerite leaching process involved the formation of zinc chloride ion complexes and evolution H2S gas. An unexpected finding is the presence of lead sulfate in the leach residue, which may be attributed to sulfide oxidation to sulfate species. The Avrami kinetic model provided an excellent fit with the sphalerite dissolution data in ChCl:PTSA:EG DES, indicating that the rate-controlling step was primarily influenced by the diffusion process. R2 values for kinetics fitting data were in the range of 0.87–0.97 for temperature of 40–100 °C. The molecular dynamic (MD) simulation findings indicated robust electrostatic interactions between the metal ions Zn2+ and Fe2+ and the Cl− ions of the ChCl molecules. Additionally, the MD calculations showed that the metal ions formed complexes with some O-S-O atoms within the PTSA molecule.

Electrodeposition of copper on glassy carbon and palladium from choline chloride - ethylene glycol deep eutectic solvent

Electrodeposition of copper from deep eutectic solvents (DES) based on a mixture of choline chloride and ethylene glycol containing CuCl2·2H2O at 50 °C and 80 °C was studied. Electrochemical reduction/oxidation of Cu(II)/Cu(0) on glassy carbon (GC) and palladium (Pd) electrodes was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) emphasizing that this process takes place through two steps, Cu(II) ↔ Cu(I) and Cu(I) ↔ Cu(0). The CV results showed that in chloride-rich DES electrolytes, the increased presence of chloro ligands raises the overpotential required for Cu electrodeposition. The electrochemical impedance spectroscopy (EIS) results indicate simultaneous electrodeposition of Cu and electrosorption of large cations on electrodeposited Cu on both GC and Pd substrates. Scanning electron microscopy (SEM) results showed that Cu grains of approximately 1 μm were obtained by electrodeposition of Cu on both Pd and GC, whereby better coverage by electrodeposited Cu was obtained on Pd than on GC. Cu electrodeposited on Pd was relatively uniform and smooth, but porous, while Cu electrodeposited on GC was dispersed in small agglomerates. Energy-dispersive X-ray spectroscopy (EDS) of Cu electrodeposited on Pd detected the dominant presence of Cu with the possibility of the formation of CuPd alloy. The presence of CuPd alloy face-centred cubic structures is confirmed by X-ray diffraction (XRD) along with metallic Cu.

Interactions between components of choline chloride/propylene glycol or ethylene glycol deep eutectic solvents in the presence of water by determination of amlodipine besylate solubility profile

Improving amlodipine besylate (AMB) solubility as a poorly water-soluble drug is one of the biggest limits in preparation of different formulations in the pharmaceutical industry. Aiming to increase the aqueous AMB solubility, its solubility in choline chloride/propylene glycol (ChCl/PG) or choline chloride/ethylene glycol (ChCl/EG) deep eutectic solvents (DESs)-water mixtures was determined here using a shake-flask way at 293.2 K–313.2 K and ambient pressure (≈85 kPa) and correlated by models of van't Hoff, Jouyban-Acree and Jouyban-Acree-van't Hoff. In these mixtures, the maximum molarities of AMB (0.297 and 0.150 mol L−1) were determined at 313.15 K when the mass fraction of ChCl/PG and ChCl/EG were 0.8 and 1.0. The maximum AMB solubility in water was (0.008 mol L−1) at 313.15 K and observed an increment of 36.7-fold and 18.5-fold in ChCl/PG + water and ChCl/EG + water, respectively. The water effect on the stability of ChCl-PG or EG hydrogen bonding interactions was investigated by measuring the molarity of AMB in ternary mixtures of ChCl + PG or EG + water at 298.15 K. Comparing the obtained results for the above-mentioned binary and ternary mixtures presented that there is no real binary mixtures of DES and water when the water mass fraction was between 0.9 to 0.4 for ChCl/PG and 0.9 to 0.2 for ChCl/EG DESs, respectively. From correlation of AMB solubility with the selected cosolvency models, the mean percentage deviations were obtained between 3.4 % to 12.3 % which are on the acceptable range. Moreover, the consequences of apparent thermodynamic analysis demonstrated an endothermic and entropy-driven dissolution of AMB in all portions of ChCl/PG or ChCl/EG + water pseudo-binary mixtures.

CO2 Capture Mechanism by Deep Eutectic Solvents Formed by Choline Prolinate and Ethylene Glycol.

The choline prolinate ([Ch][Pro]) as a hydrogen bond acceptor and ethylene glycol (EG) as a hydrogen bond donor are both used to synthesize the deep eutectic solvents (DESs) [Ch][Pro]-EG to capture CO2. The CO2 capacity of [Ch][Pro]-EG is determined, and the nuclear magnetic resonance (NMR) and infrared (IR) spectrum are used to investigate the CO2 capture mechanism. The results indicate that CO2 reacts with both the amino group of [Pro]- anion and the hydroxyl group of EG, and the mechanism found in this work is different from that reported in the literature for the [Ch][Pro]-EG DESs.

Exploration of the mechanism for the extraction of phenolic compounds in model coal tar by choline chloride:ethylene glycol deep eutectic solvents

Exploration of the mechanism for the extraction of phenolic compounds in model coal tar by choline chloride:ethylene glycol deep eutectic solvents

Development of deep eutectic solvent-based microwave-assisted extraction combined with temperature controlled ionic liquid-based liquid phase microextraction for extraction of aflatoxins from cheese samples.

In this study, for the first time, a deep eutectic solvent-based microwave-assisted extraction was combined with ionic liquid-based temperature controlled liquid phase microextraction for the extraction of several aflatoxins from cheese samples. Briefly, the analytes are extracted from cheese sample (3g) into a mixture of 1.5mL choline chloride:ethylene glycol deep eutectic solvent and 3.5mL deionized water by exposing to microwave irradiations for 60 s at 180W. The liquid phase was taken and mixed with 55μL 1-hexyl-3-methylimidazolium hexafluorophosphate. By cooling the solution in the refrigerator centrifuge, a turbid state was obtained and the analytes were extracted into the ionic liquid droplets. The analytes were determined by high-performance liquid chromatography equipped with fluorescence detector. Low limits of detection (9-23ng kg-1 ) and quantification (30-77ng kg-1 ), high extraction recovery (66%-83%), acceptable enrichment factor (40-50), and good precision (relative standard deviations ≤ 5.2%) were obtained using the offered approach. These results reveal the high extraction capability of the method for determination of aflatoxins in the cheese samples. In this method, there was no need for organic solvents and it can be considered as green extraction method.

Solvent pre-selection for binary mixtures based on the activity coefficient at infinite dilution in deep eutectic solvent: Tetraethylammonium chloride+ Ethylene glycol

The values of activity coefficient at infinite dilution (γ12∞) were reported for 27 solutes in tetraethylammonium chloride + ethylene glycol deep eutectic solvent (DES) system at a molar ratio of 1.000:1.997 by inverse gas chromatography (IGC) method at intervals of 10 K from 303.15 to 333.15 K. Then the measured γ12∞ values were used to determine the thermodynamic functions (ΔH1E,∞, ΔS1E,∞, and ΔG1E,∞). The values of selectivity (Sij∞) and capacity (kj∞) for six extraction problems (that is, heptane/toluene, benzene/methanol, heptane/thiophene, acetone/ethanol, cyclohexane/benzene, and cyclohexane/ethanol.) were calculated from experimental γ12∞ values and compared with literature values of other solvents under the same separation conditions. The results indicate that the studied DES is a potential extractant for separation of cyclohexane/ethanol and heptane/thiophene systems. The Flory-Huggins interaction parameters (χ12∞) were used to evaluate the miscibility between DES and organic probes, and the results reveal that alcohols exhibited the best solubility in tested DES. Furthermore, the Hildebrand solubility parameters (δ2) were calculated for tested DES, and the values of δ2 decreased with the increase of temperature.

Analysis of the Nucleation and Growth of Pd-Co on Glassy Carbon from Ethaline at 298 K Using the Theoretical Model for Bimetal Phases

In this project, the process of Pd-Co bimetallic electrodeposition on glassy carbon was studied using a choline chloride and ethylene glycol deep eutectic solvent (DES) at a temperature of 25 °C. The methodology applied for the electrochemical study comprised usual electrochemical techniques such as cyclic voltammetry (CV) and Chronoamperometry (CA). The latter showed the alloy reduction peaks, as well as the potential interval and sweep rates where a satisfactory response of the deposits was established. In addition, the type of nucleation of the alloy NPs is presented through theoretical models, as well as the value of the (apparent) diffusion coefficient, numerical density of active sites and nucleation frequency. Finally, the conclusions obtained prove that the DES used was as an optimal medium that favored the electrodeposition of the Pd-Co alloy.

Effective ammonia separation by non-chloride deep eutectic solvents composed of dihydroxybenzoic acids and ethylene glycol through multiple-site interaction

The effective separation of ammonia (NH3) has important implication for the conversion improvement and pollution control during the synthesis of NH3. In the present work, a novel kind of non-chloride deep eutectic solvents (DESs) were constructed from dihydroxybenzoic acids (DHBAs) and ethylene glycol (EG). The DHBA + EG DESs exhibit several weak acidic sites and hydrogen-bond sites, thus were proposed for NH3 separation. We found that the amounts of NH3 absorbed by DHBA + EG DESs are quite impressive, particularly at reduced pressures. The capacities can reach 5.64 and 11.69 mol/kg at 0.1 and 1 bar respectively, when the temperature of 298.2 K is considered. Besides, after five absorption–desorption cycles, the DHBA + EG DESs can preserve the excellent NH3 absorption performance. The DHAB + EG DESs can also selectively absorb NH3 from N2 and H2 in the mixed gas. The NH3 absorption mechanism of DHBA + EG DESs was further deeply illustrated by spectroscopic techniques and theoretical calculations.

Phase Equilibria and Mechanism Insights into the Separation of Isopropyl Acetate and Methanol by Deep Eutectic Solvents

Separation of methanol–isopropyl acetate (IPAC) obtained via isopropanol synthesis is essential. Deep eutectic solvents (DESs) have garnered extensive attention in the field of azeotropic separation owing to their advantages such as biodegradability, ecofriendliness, and cost-effectiveness. In this work, three choline-based DESs were prepared. Then, the experimental data of the synthesized DESs with methanol and IPAC were measured, which were linearly correlated with Hand and Othmer–Tobias equations. The GM/RT surface obtained using GUI-MATLAB software was used to determine the reliability of the fitting data based on the NRTL model. Choline chloride and ethylene glycol DES with a molar ratio of 1:2 exhibited the best methanol affinity. The effect of the solvent structure was studied using a combination of experimental and quantum chemistry and molecular dynamics (MD) calculations. Through electrostatic potential distribution, atoms-in-molecules, and independent gradient model analytical methods, the three DEEs were primarily extracted via a hydrogen bond interaction and van der Waals interaction, wherein the former played a dominant role in separation. MD simulation was used to reveal the effect of the structures of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) on the extraction process at the molecular level. The analysis results indicated that HBA was the main influencing factor in the separation, and the electrostatic interaction of Cl– and methanol was dominant in the separation. Additionally, HBDs were the secondary factor during the separation process. In this work, the reasons for the differences in the separation performances of different DESs were analyzed from a microscopic perspective, offering theoretical support for selecting suitable DESs for separating alcohol-containing azeotropic systems.

Effects of Thermal Cycling Rate on the Glass Transition Behavior of Choline Chloride and Ethylene Glycol Deep Eutectic Solvent Mixtures

Deep eutectic solvents (DESs) are a class of mixtures with the potential to serve as designer materials, and substitute for conventional organic solvents used in a wide variety of applications. The eutectic behavior of these mixtures has been explored in some depth, but the characteristic tendency of these materials is to behave contradictory to ideal, anticipated behavior. Therefore, experimental analyses are paramount to understanding the molecular dynamics of these materials. In this work, we have assessed a series of DESs using incremental compositions of Choline chloride (ChCl) and Ethylene glycol (EG). We have explored the rate dependence of glass phase transitions in these ChCl:EG mixtures using differential scanning calorimetry by quantifying the impacts of thermodynamic kinetics. The supporting evidence demonstrates that thermal cycling rate significantly affects glass transition temperatures, suggesting the importance of defining rate-independent transition temperatures for these mixtures.

Excess thermodynamic functions of phosphonium-based deep eutectic solvent for various organic solutes at different temperatures

BackgroundDeep eutectic solvents have presented excellent properties and have been utilized in various research areas of chemistry. These solvents have recently been reported as one of the most fascinating with promising possibilities when compared to the other solvents. MethodIn this present study, the limiting activity coefficients have been estimated for 32 various volatile organic solutes (aliphatic and aromatic hydrocarbons, alcohols, THF, thiophene, acetonitrile, ketones) and water in [trihexyltetradecylphosphonium decanoate + ethylene glycol] prepared at 1: 4 molar ratio, respectively. Measurements were conducted at different temperatures, T = (313.15–343.15) K and at atmospheric pressure. Gas liquid chromatography coupled with thermal conductivity detector was employed to obtain the experimental retention data of solutes in the deep eutectic solvent. The partial molar excess properties, such as enthalpies, entropies, and Gibbs energies were determined at infinite dilution from the calculated limiting activity coefficients. In addition, the selectivity and capacity values for the separation problems such as (acetone/ethanol, cyclohexane/benzene, benzene/toluene, and butanol/MEK) were determined from the limiting activity coefficients. FindingsThe attained values proved that trihexyltetradecylphosphonium decanoate + ethylene glycol deep eutectic solvent could be utilized in the separation of azeotropes. The results were discussed based on the intermolecular interactions occurring in the deep eutectic solvent mixtures. The influence of the hydrogen bond donor on deep eutectic solvent behavior was discussed.

A density functional theory based tight-binding study on the water effect on nanostructuring of choline chloride + ethylene glycol deep eutectic solvent.

The effect of water on the properties of an archetypical type III deep eutectic solvent [choline chloride : ethyleneglycol (1:2)] is analyzed using ab initio molecular dynamics simulations in the 0 to 60 wt. % water content range. The properties of the mixed fluids are studied considering nanostructuring, intermolecular forces (hydrogen bonding), the energy of interactions, dynamic properties, and domain analysis. The reported results confirm that the change in the properties of the studied deep eutectic solvent is largely dependent on the amount of water. The competing effect of water molecules for the available hydrogen bonding sites determines the evolution of the properties upon water sorption. The main structural features of the considered deep eutectic were maintained even for large water contents; thus, its hydrophilicity could be used for tuning fluid physicochemical properties.

Influence of Pre-Adsorbed TiO2 Particles on the Nucleation and Growth Mechanism of Ni in Deep Eutectic Solvent Electro-Codeposition

Electrodeposition holds excellent potential for creating controllable nanoscale functional interfaces. However, the key characteristics of these processes remain elusive, especially the composite electrodeposition processes involving inert nanoparticles. Herein, the pre-adsorption of inert particles is considered in detail in electro-codeposition. The nucleation and growth mechanism of nickel nanoparticles under the influence of pre-adsorbed inert particles is studied in a choline chloride–ethylene glycol deep eutectic solvent (DES). Cyclic voltammetry results show that pre-adsorbed TiO2 particles can significantly increase the cathodic reduction current, while codeposited TiO2 particles hinder the reduction process. Chronoamperometry analysis demonstrates that pure Ni electrodeposition in a DES follows the mechanism of instantaneous nucleation and tridimensional growth at a high potential, while the Ni electrodeposition deviated from the instantaneous nucleation model due to the pre-adsorption of TiO2 particles. Moreover, considering the classical model description of multiphase 3D nucleation and diffusion-controlled growth, the typical kinetic parameters such as nucleation rate constant and diffusion coefficient were investigated under different applied potentials. It was found that the nucleation rate constant of Ni electrodeposition increased significantly in the presence of pre-adsorbed TiO2 particles. These findings are of great significance for understanding and perfecting the electro-codeposition process containing inert nanoparticles.

Electrochemical Fabrication of Tin Films on Different Substrates in a Choline Chloride–Ethylene Glycol Deep Eutectic Solvent Containing Boric Acid

Electrochemical Fabrication of Tin Films on Different Substrates in a Choline Chloride–Ethylene Glycol Deep Eutectic Solvent Containing Boric Acid

Efficient separation of electrode active materials and current collector metal foils from spent lithium-ion batteries by a green deep eutectic solvent

The opposite electrostatic potential between the oxygen atoms on the carbonate ion and the hydrogen atoms on PVDF makes the potassium carbonate–ethylene glycol deep eutectic solvent suitable for electrode material separation.

Development of sodium hydroxide-induced homogenous liquid-liquid extraction-effervescent assisted dispersive liquid-liquid microextraction based on deep eutectic solvents; Application in the extraction of phytosterols from cow cream samples

In this study, sodium hydroxide-induced homogenous liquid-liquid extraction was combined with effervescent assisted-dispersive liquid-liquid microextraction and used for the extraction of phytosterols (lupeol, β-sitosterol, stigmasterol, campesterol, and brassicasterol) from cream samples. Two types of deep eutectic solvents (water-miscible and water-immiscible solvents) were prepared and used in the extraction procedure. In this approach, firstly, the sample was dissolved in a mixture of n-hexane and tetrabutylammonium bromide: ethylene glycol deep eutectic solvent (as extraction/disperser solvent) and a homogenous solution was obtained. After that, a few microliters of sodium hydroxide solution (as fatty acid saponification and phase separation agent) was quickly injected into the mixture. By doing so, a three-phase system was formed. Then, the supernatant phase (tetrabutylammonium bromide: ethylene glycol deep eutectic solvent) was removed and mixed with tetrabutylammonium bromide: dichloroacetic acid: octanoic acid deep eutectic solvent. The obtained solution was applied in the microextraction step. To obtain effective, reliable, robust, accurate, and precise analytical results, the effective parameters for the presented method were investigated and optimized in detail. Detection limits, extraction recoveries, and enrichment factors were in the ranges of 0.06–0.26 μg kg–1, 86–93 %, and 215–232, respectively. Intra- and inter-day repeatabilities were investigated at a concentration of 1.5 μg kg–1 (each analyte) and they were in the ranges of 5.3−7.5 and 7.2–8.8 %, respectively. Finally, the presented method was easily used in determination of the phytosterols in cow milk cream samples.