Deep Eutectic Solvent System Research Articles

Comparative of malonic acid aqueous solution and malonic acid-based deep eutectic solvent for LiCoO2 cathode materials recovery: Leaching efficiency and mechanism

Deep eutectic solvents (DESs) and aqueous organic acids are two leaching systems that have achieved remarkable results in hydrometallurgical recovery of spent lithium-ion batteries (LIBs). However, previous studies have only evaluated a single leaching system at a time and thereby failed to compare the differences between DES and organic acids systems in detail. In this study, our purpose was to clarify the differences between the efficiencies of two leaching systems—a malonic acid (MA) aqueous solution and a DES of choline chloride: malonic acid (ChCl:MA) via a systematic investigation of the conditions and mechanisms associated with the leaching of LiCoO2 cathode materials using these two systems. The effects exerted by various process parameters, such as reaction time, temperature, and liquid-to-solid ratio, on the leaching efficiency of these two systems were investigated. The results showed that the Co and Li leaching efficiencies of the DES were higher than those of the MA aqueous solution under identical experimental conditions. The kinetic differences between the two systems were reflected in the fact that the MA aqueous solution was regulated by diffusion, whereas the DES leaching was regulated by chemical reactions. Spectroscopic analysis and density functional theory calculations indicated that MA acts as both a ligand and a reducing agent in aqueous solutions, whereas MA in the DES only acts as a reducing agent. In addition, Co was present in the MA aqueous and DES leaching solutions as octahedral (Co(H2O)2(C3H2O4)2) and tetrahedral ([CoCl4]2-), respectively.

An integrated process by ultrasonic enhancement in the deep eutectic solvents system for extraction and separation of chlorogenic acid from Eucommia ulmoides leaves

This study established an integrated process for the extraction and enrichment of chlorogenic acid(CGA)from Eucommia ulmoides leaves in a deep eutectic solvent system via ultrasonic wave-enhanced adsorption and desorption practices utilizing macroporous resins. Although deep eutectic solvents (DESs) have the advantages of chemical stability, good dissolving capacity, and nonvolatilization, routine solvent recovery operations are not suitable for subsequent separation in this solvent system. Based on the above characteristics, this study integrated the extraction and enrichment processes, in which DESs extracts directly loaded onto the macroporous adsorption resin, avoiding the loss of target components in solvent recovery and redissolution processes. The screening results of solvents and resin types further showed that choline chloride-malic acid (1:1) was the optimal DES, and the NKA-II resin had high adsorption and elution performance for CGA. The viscosities of the DESs were much higher than those of water and conventional organic solvents; thus, the mass transfer resistance was large, which could also affect the adsorption behaviour of the macroporous resin. The thermal and mechanical effects of ultrasound could effectively enhance the efficiency of the mass transfer, adsorption, and desorption in the DES systems. When compared to no sonication treatment, the CGA adsorption at various ultrasonic powers (120–600 W) was examined. At optimal ethanol concentration (60%), the effect of the ultrasonic treatment on the recovery of the DESs (water eluting process) and the desorption capability of CGA were confirmed. The use of three volumes of water elution could recover the DESs without loss of CGA. The adsorption process significantly differed depending on the ultrasonic settings, and the absorption balance time and experimental adsorption capacity at equilibrium were enhanced. Additionally, the adsorption procedure of the NKA-II macroporous resin for CGA under ultrasonic treatment could be clarified by the pseudo second order kinetic equation and the Freundlich isotherm model. Thermodynamic and dynamic parameters indicated that physical adsorption was the main process of the entire procedure, and it was a spontaneous, exothermic, and entropy-reducing physical adsorption process. This study potentially indicates that the use of ultrasonication, as a high-efficiency, environmentally friendly method, can enhance the features of the macroporous resin to better purify target chemicals from a DES extract.

Extraction of protein from sesame meal: Impact of deep eutectic solvents on protein structure and functionality

There is an increasing need for sustainable sources of dietary protein. Sesame meal is a protein-rich waste from the industrial production of sesame oil. It could help meet this need if high quality protein could be extracted from the meal in an environmentally friendly way. The traditional alkali-soluble acid precipitation extraction process produces proteins with poor functionality and harmful to the environment. Deep eutectic solvents (DESs) offer a novel, sustainable approach to protein extraction. In this study, four DES systems (choline chloride-glycerol, choline chloride-ethylene glycol, choline chloride-oxalic acid, and choline chloride-glycolic acid) were designed and tested in 3 M ratios (10 sample solutions). Extracted proteins were compared with protein extracted by traditional alkali-soluble acid precipitation in terms of structure and function. The choline chloride-ethylene glycol system extracted protein with a purity of 93.3%. The choline chloride-oxalic acid system performed well in terms of solubility, emulsification, foaming and thermal stability. These results indicate that deep eutectic solvents can effectively extract sesame protein with characteristics appropriate for use in the food industry. This research lays the groundwork for high-value utilization of sesame meal, which is currently discarded as waste.

Integrated strategies for furfural production and lignocellulose fractionation in aqueous deep eutectic solvents

The current biomass refinery pretreatment using deep eutectic solvents (DES) has primarily focused on downstream utilization of cellulose and lignin, while often overlooking the potential of hemicellulose. Herein, an innovative and integrated strategy was proposed for simultaneous production of furfural (FF) and fractionation of lignin and cellulose from biomass using the same aqueous DES. To achieve this goal, response surface methodology (RSM) was employ to optimize the dilute hydrochloric acid (HA) pretreatment of corn stover, a representative of lignocellulosic material, ensuring complete removal of hemicellulose. The resulting hemicellulose hydrolysate was then efficiently converted into FF in aqueous DES system, achieving an impressive yield of 72.82 %. By introducing MgCl2 as a catalyst, the FF yield soared to an exceptional 86.94 %. Furthermore, a plausible mechanism was elucidated for the conversion of hemicellulose to FF in the aqueous DES. Concurrently, the solid residue resulting from the dilute HA pretreatment was fractionated using the same aqueous DES, successfully extracting cellulose and lignin fractions. Notably, the separated cellulose solid residue exhibited an outstanding digestion efficiency of 96.3 % after 72 h of enzymatic hydrolysis at 30 FPU/g, as confirmed through meticulous FTIR analyses. In addition, an advanced 2D-HSQC NMR technique was utilized to unveil the intricate structure of the obtained lignin, revealing a guaiacol-syringyl-p-hydroxyphenyl (G-S-H) type lignin enriched with abundant CH3O- and β-O-4 linkages. A mass balance analysis showed the production of 14.0 g FF, 31.9 g glucose and 14.2 g lignin from 100 g dry corn stover. This state-of-the-art approach presented not only pioneers a novel avenue for the concurrent production of FF but also offers a sustainable and eco-friendly method for the fractionation of lignin and cellulose using DES solvents.

Sustainable extraction of polyphenols from vine shoots using deep eutectic solvents: Influence of the solvent, Vitis sp., and extraction technique

Vine shoots are the main by-products of grapevine pruning with no added value. In the present study, deep eutectic solvents (DESs) were used as alternatives to traditional chemical solvents, for the extraction of phytochemicals from grapevine shoots. Three levulinic acid-based DESs were tested for the first time, and their performance was compared to methanol (a standard chemical solvent) regarding the extraction of phenolic compounds from thirteen Vitis sp. shoots. Two extraction methods have been applied: ultrasound-assisted extraction and solid-liquid extraction. A total of eleven polyphenols which belongs to four families (proanthocyanins, stilbenes, hydroxycinnamic acids, and flavonols) have been identified and quantified in the extracts.The statistical analysis shows that the levulinic acid-based DES systems are novel and important alternatives to chemical solvents due to favourable eco-friendly properties and remarkable extraction performance of polyphenols. On the other hand, the ultrasound-assisted extraction technique has significantly increased the extraction rate in comparison to the solid-liquid extraction method with p-values lower than 0.05 for most compounds. The genetic factor has been shown to play an important role in the content of extracted polyphenols, being V. riparia pubescente the one that presented the highest concentrations of extracted polyphenols. Finally, the polyphenol-enriched extracts have proven important properties such as antioxidant activity and significant delay in bacteria growth against both gram-positive and gram-negative bacteria. It is important to note that, to the best of our knowledge, this is the first time that deep eutectic solvents have been used for the extraction of bioactive compounds from vine shoot residues.

Investigation of the effects of ternary deep eutectic solvent composition on pretreatment of sorghum stover

AbstractBiomass‐derived deep eutectic solvents (DESs) have been introduced as promising pretreatment and fractionation solvents because of their mild processing conditions, easy synthesis, and green solvent components from biomass. In recent DES studies, solvent‐based third constituents like water, ethanol, and others improve the processibility of typical binary DESs. However, the impacts of these components are not well understood. Here, two solvent‐based constituents, including water and ethylene glycol, were applied to 3,4‐dihydroxybenzoic acid (DHBA)‐based DES system for improving the conversion efficiency of cellulose‐rich fraction and the properties of lignin fraction. Chemical composition, enzymatic digestibility, degree of polymerization of cellulose and physicochemical properties of lignin were used to evaluate the impact of each third constituent on biomass processing. Ternary ChCl‐DHBA DESs exhibited better performances in delignification, fermentable sugar production, and preservation of β‐O‐4 ether linkage in lignin compared with binary ChCl‐DHBA DES.

Pickering Emulsions and Hydrophobized Films of Amphiphilic Cellulose Nanofibers Synthesized in Deep Eutectic Solvent.

Herein, a dual-functioning deep eutectic solvent system based on triethylmethylammonium chloride and imidazole was harnessed as a swelling agent and a reaction medium for the esterification of cellulose with n-octyl succinic anhydride (OSA). The modified or amphiphilic cellulose nanofibers (ACNFs), synthesized using three different OSA-to-anhydroglucose unit molar ratios (0.5:1, ACNF-1; 1:1, ACNF-2; and 1.5:1, ACNF-3), were further converted into nanofibers with degree of substitution (DS) values of 0.24-0.66. The ACNFs possessed a lateral dimension of 4.24-9.22 nm and displayed surface activity due to the balance of hydrophobic and hydrophilic characteristics. The ACNFs made stable aqueous dispersions; however, the instability index of ACNF-3 (0.51) was higher than those of ACNF-1 (0.29) and ACNF-2 (0.33), which was attributed to the high DS-induced hydrophobicity, causing the instability in water. The amphiphilic nature of ACNFs promoted their performance as stabilizers in oil-in-water Pickering emulsions with average droplet sizes of 4.85 μm (ACNF-1) and 5.48 μm (ACNF-2). Self-standing films of ACNFs showed high contact angles for all the tested DS variants (97.48-114.12°), while their tensile strength was inversely related to DS values (ACNF-1: 115 MPa and ACNF-3: 49.5 MPa). Aqueous dispersions of ACNFs were also tested for coating fruits to increase their shelf life. Coatings improved their shelf life by decreasing oxygen contact and moisture loss.

Ion clustering, aggregation and diffusion in amide based deep eutectic solvents: A microstructural investigation using various NMR spectroscopic techniques and molecular dynamics simulation

A thorough understanding of the structure and dynamics of deep eutectic solvents (DESs) is necessary to optimize the uses of this new class of solvents for many potential applications. Herein, we have studied ion clustering, aggregation and diffusion mechanism in DESs composed of acetamide and sodium/potassium thiocyanate using 1D NMR, pulsed field gradient stimulated echo (PFGSE) NMR and 2D nuclear Overhauser effect spectroscopy (2D NOESY) techniques, and molecular dynamics simulation. We have varied the fraction of salts to investigate the composition dependent microscopic structural insight. A great enhancement in diffusion coefficient (D) of acetamide with increasing the fraction of KSCN (fKSCN) has been observed in PFGSE measurements. The experimental diffusion activation energy (Ea) decreases significantly with increasing fKSCN, which is in excellent agreement with the Ea values obtained from simulated mean squared displacements (MSD). The calculated radial distribution functions (RDF) indicate that the Na+ ions strongly coordinate with acetamide molecules and form ion-clusters and aggregated structures in the medium. However, as Na+ ions are gradually replaced by K+ ions, ion-clustering and aggregation decrease due to relatively weak coordination ability of larger cation, which supports the enhancement of experimental D with increasing fKSCN. In the 2D NOESY study, the intensity of the cross peaks between methyl and amide protons of acetamide decreases relative to the diagonal peak intensity as the fKSCN increases in the medium. This study indicates that the extent of intermolecular NOE reduces as the structural flexibility increases due to less efficient ion-clustering with increasing K+ ion concentration, thus strongly corroborates the results from PFGSE experiment and simulation. Furthermore, 1D and 2D NMR data exhibit an intramolecular chemical exchange between two amide protons in acetamide, the extent of which increases with increasing temperature as well as fKSCN in the DES system. The present study provides a multifaceted picture of composition-dependent distinct microstructures in DES.

Machine learning prediction of delignification and lignin structure regulation of deep eutectic solvents pretreatment processes

Prediction of the pretreatment efficiency of lignocellulosic biomass with ternary deep eutectic solvents (DES) containing Lewis acids by machine learning (ML). Principal component analysis, partial least square method, spearman correlation matrix, random forest, extreme gradient boosting and deep neural network were used to elucidate the correlation between 77 variables and the mechanism of lignin depolymerization. The effects of raw material composition, reaction conditions, physicochemical properties of DES and structural parameters in lignin on 9 target variables including β-O-4 bond, β-β bond, β-5 bond, weight average molecular weight, number average molecular weight, polydispersity index, ratio of syringyl units to guaiacyl units, content of phenolic hydroxyl groups and delignification were analyzed. Multivariate analysis showed that temperature, polarity related parameters of HBD and acidity of Lewis acids contributed significantly to the degree of lignin depolymerization. The types and fracture mechanisms of the bonds between different structural units of lignin can be determined by the analysis of structural parameters. XGBoost model has the best performance among all the ML models, and the R square of the test sets for the target variables is above 0.76. Feature importance analysis showed that structural parameters significantly affected the pretreatment effect. The physical and chemical parameters of HBD, such as dipole moment, Log P and surface tension should be paid attention to in the design of DES. The study of the weak intermolecular forces in the lignin and DES systems is beneficial to reveal the mechanism of the pretreatment process. This study provides novel insights into the structural regulation and high-value utilization of lignin in the process of DES pretreatment of lignocellulosic biomass.

Electrochemical preparation of nanostructure zinc oxide in emulsion deep eutectic solvents mixtures

Deep eutectic solvents (DESs) offer important advantages over classical nano-metal oxides based on eutectic systems as a result of important characteristics based on forming significant molecular design and appropriate diminution molecules; they can be candidates as fundamental materials in electrochemistry applications, such as batteries, nanogenerators, and solar cells. In this study, an ethaline: oxaline 1:1 M ratio was successfully applied to synthesize uniform nano zinc oxide using polyaniline polymer molecules as an additive. The deep eutectic solvent system exhibited new and novel active media for synthesising ZnO nanoparticles. The addition of aniline and water molecules to DES media significantly supported the formation of zinc oxide nanoparticles. Nano zinc oxide was synthesised from extracted olive leaves. The olive leaves were extracted using digestion systems in aniline: ethaline: oxaline deep eutectic solvent systems. Deep eutectic solvent emulsions have been assessed as effective synthesis media in current electrochemical processes because they are inexpensive and environmentally friendly. They produce ZnO nanocrystals with 37 nm diameters dispersed in homogeneous reagents, whereas the morphology of ZnO nanocomposites prepared in a microemulsion exhibits significant structure and 50–100 nm ZnO nanoparticles. In electrochemical synthesis conditions, when using the electrochemical method, microemulsion systems were found to serve as enhancement media for forming special structures of ZnO nanocomposite cooperate together with aniline, exhibiting excellent electrochemical activity.

Lithium-Ion Battery Cathode Recycling through a Closed-Loop Process Using a Choline Chloride-Ethylene Glycol-Based Deep-Eutectic Solvent in the Presence of Acid.

This study evaluates the ability of a choline chloride:ethylene glycol-based deep eutectic solvent (DES) to dissolve lithium cobalt oxide (LCO) which is used as a cathode active material in Li-ion batteries. Both a commercial powder and spent cathodes have been used. It was demonstrated that if HCl is added in a small proportion, a rapid and efficient LCO dissolution can be achieved. Indeed, if more than three protons are added per one cobalt atom present in the LCO structure, a complete dissolution of the material is accomplished within 2 h at 80 °C. This result might be considered as a viable alternative compared to the literature where much longer reaction times and higher temperatures are applied to achieve similar results with the same DES system used either pure or in presence of additional reducing agents. It was further demonstrated that Co and Li can be fully precipitated after Li2 CO3 addition. This precipitation does neither pollute the DES nor leads to its degradation provided the pH does not exceed 10. Finally, it was shown that two additional reuse cycles can be carried out without any decrease of recovery efficiency, while no degradation products have been detected within the DES phase.

Uncovering the Critical Factors that Enable Extractive Desulfurization of Fuels in Ionic Liquids and Deep Eutectic Solvents from Simulations.

Environmental regulatory agencies have implemented stringent restrictions on the permissible levels of sulfur compounds in fuel to reduce harmful emissions and improve air quality. Problematically, traditional desulfurization methods have shown low effectiveness in the removal of refractory sulfur compounds, e.g., thiophene (TS), dibenzothiophene (DBT), and 4-methyldibenzothiophene (MDBT). In this work, molecular dynamics (MD) simulations and free energy perturbation (FEP) have been applied to investigate the use of ionic liquids (ILs) and deep eutectic solvents (DESs) as efficient TS/DBT/MDBT extractants. For the IL simulations, the selected cation was 1-butyl-3-methylimidazolium [BMIM] and the anions included chloride [Cl], thiocyanate [SCN], tetrafluoroborate [BF4], hexafluorophosphate [PF6], and bis(trifluoromethylsulfonyl)amide [NTf2]. The DESs were composed of choline chloride with ethylene glycol (CCEtg) or with glycerol (CCGly). Calculation of excess chemical potentials predicted the ILs to be more promising extractants with energies lower by 1-3 kcal/mol compared to DESs. Increasing IL anion size was positively correlated to enhanced solvation of S-compounds, which was influenced by energetically dominant solute-anion interactions and favorable solute-[BMIM] π-π stacking. For the DESs, the solvent components offered a range of synergistic, yet comparatively weaker, electrostatic interactions that included hydrogen bonding and cation-π interactions. An in-depth analysis of the structure of IL and DES systems is presented, along with a discussion of the critical factors behind experimental trends of S-compound extraction efficiency.

Structural characterization and stability of glycated bovine serum albumin-kaempferol nanocomplexes.

Kaempferol (Kae), a flavonoid is endowed with various functions. However, due to its poor water solubility and stability, its application in the food and pharmaceutical fields remains elusive. Emerging reports have emphasized the importance of bovine serum albumin (BSA), and glycosylated BSA (GBSA) prepared in the nature deep eutectic solvent system as drug delivery system carriers. In our study, ultraviolet and fluorescence spectra revealed the higher interactions of BSA and GBSA with Kae. Through analysis of Z-average diameter, zeta-potential, polydispersity index (PDI), encapsulation efficiency (EE), loading capacity (LC) of BSA-Kae nanocomplexes (NPs) and GBSA-Kae NPs, GBSA-Kae NPs showed a higher absolute value of zeta-potential and lower PDI, while its EE and LC were also higher. Structural characterization and stability analysis revealed that GBSA-Kae NPs had more stable properties. This study laid the theoretical foundation for improving the solubility and stability of Kae during its delivery and transport.

Solubility of Some Drugs in Aqueous Solutions of Choline Chloride-Based Deep Eutectic Solvent Systems: Experimental Data, Modeling, and the Impact of Solution pH.

The solubility of drugs in water and organic solvents is a crucial factor in numerous pharmaceutical processes. In recent years, a new type of solvent called deep eutectic solvents (DESs) has been developed as a useful solvent for drugs. Choline chloride-glycerol/urea (ChCl-G/U) systems are DESs recognized as a novel category of environmentally friendly solvents. One recent application of this type of DES in water is the solubilization of drugs. This study aimed to investigate the solubility of certain drugs in ChCl-G/U. In addition, the solubilization mechanisms of the DESs studied, and quantitative structure-property relationship (QSPR) models for solubilization were proposed. The solubility of 13 drugs in an aqueous solution of the ChCl-G/U system was investigated using the shake flask method. The study was conducted at 10% and 50% mass fractions of the studied systems. Multiple linear regression models were used to develop mathematical relationships between the solubilization of the studied compounds in the presence of ChCl-G/U + water mixture using QSPR models. The solubility of the compounds showed a significant increase upon adding ChCl-G/U to the aqueous solutions. Based on the data obtained, QSPR models were developed using solubilization ratio and structural descriptors. The experimental data demonstrates the potential of utilizing ChCl-G/U as a medium to enhance the solubility of poorly soluble drugs in water. Solubilization of solutes in ChCl-G/U + water mixtures could be correlated with the structural properties of drugs. Moreover, the final pH of the solutions in ChCl-U is a critical factor that must be considered when using this system for solubilization.

Exploration of the interaction mechanism of lignocellulosic hybrid systems based on deep eutectic solvents

The interactions of three deep eutectic solvents (DES) choline chloride-glycerol (ChCl-GLY), ChCl-lactic acid (ChCl-LA) and ChCl-urea (ChCl-U) with cellulose-hemicellulose and cellulose-lignin hybrid systems were investigated using the simulated computational approach. Aiming to simulate DES pretreatment of real lignocellulosic biomass in nature. DES pretreatment could disrupt the original hydrogen bonding network structure among the lignocellulosic components and reconstruct the new DES-lignocellulosic hydrogen bonding network structure. ChCl-U had the highest intensity of action on the hybrid systems, removing 78.3% of the hydrogen bonds between cellulose-4-O-methyl Gluconic acid xylan (cellulose-Gxyl) and 68.4% of the hydrogen bonds between cellulose-Veratrylglycerol-b-guaiacyl ether (cellulose-VG), respectively. The increase of urea content facilitated the interaction between DES and lignocellulosic blend system. Finally, the addition of appropriate water (DES:H2O = 1:5) and DES formed the new DES-water hydrogen bonding network structure more favorable for the interaction of DES with lignocellulose.

Deep eutectic solvent-ultrasound assisted extraction as a green approach for enhanced extraction of naringenin from Searsia tripartita and retained their bioactivities.

Naringenin (NA) is a natural flavonoid used in the formulation of a wide range of pharmaceutical, fragrance, and cosmetic products. In this research, NA was extracted from Searsia tripartita using an environmentally friendly, high efficiency extraction method: an ultrasound-assisted extraction with deep eutectic solvents (UAE-DES). Six natural deep eutectic solvent systems were tested. Choline chloride was used as the hydrogen bond acceptor (HBA), and formic acid, ethylene glycol, lactic acid, urea, glycerol, and citric acid were used as hydrogen bond donors (HBD). Based on the results of single-factor experiments, response surface methodology using a Box-Behnken design was applied to determine the optimal conditions for UAE-DES. According to the results, the optimal NA extraction parameters were as follows: DES-1 consisted of choline chloride (HBA) and formic acid (HBD) in a mole ratio of 2:1, an extraction time of 10 min, an extraction temperature of 50°C, an ultrasonic amplitude of 75 W, and a solid-liquid ratio of 1/60 g/mL. Extracted NA was shown to inhibit the activity of different enzymes in vitro, including α-amylase, acetylcholinesterase, butyrylcholinesterase, tyrosinase, elastase, collagenase, and hyaluronidase. Thus, the UAE-DES technique produced high-efficiency NA extraction while retaining bioactivity, implying broad application potential, and making it worthy of consideration as a high-throughput green extraction method.

Deep eutectic solvent-modified mesoporous silica for CO2 capture: A new generation of hybrid sorbents

The escalating level of atmospheric carbon dioxide (CO2) is currently one of the most pressing environmental concerns for scientists. Consequently, a wide range of sorbents are investigating for their CO2 uptake ability. Studies showed that morphology-controlled mesoporous silica (MPS) and deep eutectic solvents (DESs) perform exceptionally well towards CO2 capture. However, based on their respective physicochemical properties, both MPS and DES systems have their own drawbacks when used separately. A novel strategy is adopted here by combining MPS and DES [choline chloride: ethylene glycol (ChCl: EG):: 1: 2 mol ratio] to prepare a hybrid high-performing porous sorbent - porous DES (PDES) for CO2 capture. PDES has shown superior CO2 capture capacity relative to the DES (ChCl: EG) alone. CO2 capture efficiency of PDES system was further improved by adding superbases 1,5-diazabicyclo[4.3.0]–non-5-ene (DBN). DBN-added PDES system exhibited remarkable CO2 uptake efficiency of 72.4 mg/g (mg of CO2 captured/g of liquid media) and excellent CO2 absorption-expulsion reversibility. The work establishes that a functional MPS-DES combination can enhance CO2 absorption dramatically creating a new generation of high-performing, inexpensive, environmentally-friendly, and widely accessible porous liquid material as effective CO2 sorbent.

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.

Deep Eutectic Solvent-based green extraction and gas chromatography determination of phthalates released from food contact materials

A sensitive and efficient green emulsification liquid-liquid microextraction (ELLME) method using deep eutectic solvents (DES) for extraction of phthalates released from food contact materials (FCMs) was optimized for GC-MS determination of Butyl Benzyl Phthalate (BBP) and Di-2-Ethylhexyl Phthalate (DEHP). The optimal DES system for phthalate extraction was determined to be Choline Chloride:Phenol (1:2 molar ratio). Tetrahydrofuran (THF) was utilized as the emulsifier solvent. The effects of vortex agitation times and centrifugation times on extraction efficiency were investigated. The method yielded quantification limits (LOQ) of 0.036 and 0.005 mgL-1 for BBP and DEHP, respectively. Repeatability relative standard deviations (RSDr) of 2.9% and 2.2% were obtained for BBP and DEHP, respectively, while corresponding medium precision relative standard deviations (RSDR) were 2.8% and 3.2%. Recovery rates from spiked samples were 94.8% for BBP and 95.1% for DEHP. Finally, determination of BBP and DEHP released from contact materials into water and beverage samples at various temperatures confirmed the applicability of the method for assessment of phthalates and their migration from FCMs.

A novel CO2-sensitive in situ deep eutectic solvent system: Efficient extraction of polyphenol phytochemicals

In the present study, monoethanolamine (MEA) was applied as a solvent for the extraction of polyphenols from lingonberry (Vaccinium vitis-idaea L.) pomace. In addition to solvent extraction an in situ DES could be formed with the secondary metabolites to obtain higher extraction yield. FT-IR, DSC, and TGA were used to validate MEA-based in situ DESs with reference compound. And the reusability of the solvent system still reached about 70.2% after the fifth cycles. The Box-Behnken experimental design method was used to determine the extraction efficiency under optimal conditions in practical applications, and the highest extraction yields of polyphenols increased 1.06–1.21 folds higher than that of traditional solvents. In addition, the extraction mechanism was studied using density functional theory. In summary, this study proposed a green and sustainable strategy to replace traditional solvents for targeted extraction of polyphenols from plants.