Effect Of Deep Eutectic Solvents Research Articles

Effect of deep eutectic solvents on the biocatalytic properties of β-glucosidase@ZnOFe nano-biocatalyst

In this work, we investigate the use of aqueous deep eutectic solvents (DESs) consisting of different hydrogen bond acceptors (choline chloride, ammonium salts or betaine) and hydrogen bond donors (amines, sugars and alcohols), as co-solvents in biocatalytic reactions catalyzed by a nano-biocatalyst with β-glucosidase (BGL) activity. For this purpose, β-glucosidase from Thermotoga maritima was immobilized on the surface of green zinc oxide-iron oxide nanoparticles (BGL@ZnOFe) derived from an aqueous olive leaf extract. The covalent bonding of β-glucosidase on the surface of nanoparticles was demonstrated by X-ray photoelectron spectroscopy. The effect of a wide range of DES solutions on the biocatalytic features of BGL@ZnOFe was thoroughly investigated. The concentration of DES as well as the specific combination of hydrogen bond acceptors and hydrogen bond donors had a significant impact on the hydrolytic activity of immobilized β-glucosidase. Most choline chloride and betaine-based DESs enhanced the enzymatic activity and thermal stability of BGL@ZnOFe up to 50%. The enzymatic activity of the nano-biocatalyst towards the hydrolysis of bioactive phenolic compounds depends on the nature of the DES used. Choline chloride:butylene glycol-based medium had beneficial effect on a transglycosylation reaction, such as the synthesis of salidroside, increasing the total turnover number of the biocatalytic process by 55%. This work indicates that the use of several choline chloride and betaine-based DESs can be successfully employed as green co-solvents in various hydrolytic and synthetic biocatalytic processes.

Ternary Liquid-Phase Equilibria of an Azeotropic Mixture (Heptane + Isopropyl Alcohol) with Deep Eutectic Solvents

The present study reports the result of the measurement and analysis of the solubility curve and tie-line data of four ternary systems containing heptane–isopropyl alcohol azeotrope mixtures and deep eutectic solvents (DESs) at T = 298.2 K and p = 0.1 MPa. This investigation is aimed to evaluate the efficiency of the prepared DESs as extractants in the separation of the heptane–alcohol azeotropic mixtures through liquid–liquid extraction (LLE) processes. In this study, four choline chloride-based DESs were prepared by a heating process. Two hydrogen bond donor (HBD) compounds (i.e., ethylene glycol and propylene glycol) were chosen in the preparation of the DESs. The solubility curves show that the effect of DESs on the immiscibility region is small. The studied systems display the type-1 LLE behavior. The measured tie-line values were adequately fitted through the nonrandom two-liquid (NRTL) thermodynamic model, and the interaction parameter values were determined. The correlation data appeared to be in good agreement with the measured tie-lie data. The extraction capacity (distribution constants and selectivities) of the studied DESs was determined. The DESs had high and similar selectivity values for the studied systems. Moreover, the distribution constants were larger than unity, indicating a favorable solvent-to-feed ratio.

Antiamoebic properties of salicylic acid-based deep eutectic solvents for the development of contact lens disinfecting solutions against Acanthamoeba

Acanthamoeba castellanii is a protist pathogen that can cause sight-threatening keratitis and a fatal infection of the central nervous system, known as granulomatous amoebic encephalitis. In this study, effects of five malonic acid and salicylic acid-based deep eutectic solvents (DES) on A. castellanii were investigated. These are salicylic acid-trioctylphosphine (DES 1), salicylic acid- trihexylamine (DES 2), salicylic acid-trioctylamine (DES 3), malonic acid-trioctylphosphine (DES 4) and malonic acid-trihexylamine (DES 5). The experiments were done by performing amoebicidal, encystment, excystment, cytopathogenicity, and cytotoxicity assays. At micromolar dosage, the solvents DES 2 and DES 3 displayed significant amoebicidal effects (P < 0.05), inhibited encystment and excystment, undermined the cell-mediated cytopathogenicity of A. castellanii, and also displayed minimal cytotoxicity to human cells. Conversely, the chemical components of these solvents: salicylic acid, trihexylamine, and trioctylamine showed minimal effects when tested individually. These results are very promising and to the best of our knowledge, are reported for the first time on the effects of deep eutectic solvents on amoebae. These results can be applied in the development of new formulations of novel contact lens disinfectants against Acanthamoeba castellanii.

Effects of Deep Eutectic Solvents on cellulosic fibres and paper properties: Green “chemical” refining

This work aims to study the effects of Deep Eutectic Solvents (DES) on cellulosic fibre structure. A focus was made on the induced fibrillation phenomena which could facilitate the further production of microfibrillated cellulose. Three DES of different pH (acid, neutral and alkaline), namely betaine hydrochloride-urea, choline chloride-urea and choline chloride-monoethanolamine, were tested. Eucalyptus and cotton pulps were used to investigate the effects of DES on both hemicelluloses and cellulose. Interestingly, cellulose was esterified during acidic DES treatment. Moreover, an internal and external fibrillation occurred with DES treatment without a great extent of modification in terms of chemical composition, crystallinity and degree of polymerisation. Compared to enzymatic hydrolysis (used as a conventional pre-treatment for cellulose microfibrillation), DES have significantly enhanced the mechanical properties of resulting papers. To conclude, DES treatment can be considered as a soft and green “chemical” refining that could be applied as a pre-treatment for cellulose microfibrillation.

Copper Deposition on Au(111) in a Deep Eutectic Solvent: An In Situ STM Study**

AbstractElectrolyte composition can have significant influences on metal deposition. In this work we employ in‐situ scanning tunneling microscope (STM), together with electrochemical methods to investigate Cu deposition on Au (111) in ethaline containing CuCl2. Cyclic voltammograms in the Cu overpotential deposition regime are dominated by a rapidly rising cathodic current, accompanied by a preceding shoulder. Instantaneous nucleation and three‐dimensional growth are discerned for the Cu deposition at larger overpotential. In‐situ STM reveals the shoulder process is associated with the formation of monoatomic‐height clusters. Meanwhile, morphology evolutions of Cu nuclei along with time and potential are followed, and layered hexagonal and hexagon fortress shaped Cu nuclei and their growth are directly observed. Furthermore, atomic‐resolution imaging elucidates an ordered incommensurate (6×√79) adsorption structure on the surface of a Cu nucleus. Our observations are helpful in gaining deeper insights into the effect of deep eutectic solvents (DES) on Cu deposition at microscopic level.

Impact of deep eutectic solvents (DESs) and individual DES components on alcohol dehydrogenase catalysis: connecting experimental data and molecular dynamics simulations

The systematic study on the effects of DESs and their individual components with the joint forces of experiments and MD simulations for the design of enzyme-compatible green solvents.

Study on the effects of deep eutectic solvents as a reaction media on the micromorphology of hydrogen-substituted graphyne and its adsorption and electrochemical properties

The choice of reaction medium had a major influence on the micro-morphology, surface area and pore volume. The 18 hydrogen-substituted graphynes (HsGYs) were synthesized with various deep eutectic solvents (DESs) as the reaction medium by coupling polymerization. The results showed that DESs had the great influence on the morphology of HsGYs. Meanwhile, HsGYs with larger surface area can be obtained by using DESs with low density and hydrophobicity as the solvent. The structure and properties of materials were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectrometer, X-ray diffractomer, UV–Vis DRS spectrum, etc. The electrochemical and adsorption properties of samples with different morphologies were tested and analyzed. The cyclic voltammetry curves showed that the samples had good capacitance behavior. HsGY-1 and HsGY-3 had relatively small contact resistance through electrochemical impedance spectroscopy analysis. The adsorption experiments showed that HsGY-12 and HsGY-13, with the larger specific surface area (336.229 and 325.005 m2g−1), had the strongest adsorption performance to chrysophanol acid (28.5 and 29.2 mg g−1). By studying the influence of DESs as a reaction solvent on the properties of HsGYs, such as morphology and specific surface area, which provided reference for the synthesis method of polymers and its application in the fields of energy storage, separation analysis and gas adsorption.

Efficient Visible-Light-Driven RAFT Polymerization Mediated by Deep Eutectic Solvents under an Open-to-Air Environment

In this work, we investigate the effects of deep eutectic solvents (DESs) on a facile reversible addition–fragmentation chain-transfer (RAFT) polymerization driven by visible light. A DES composed of tetrabutylammonium chloride (TBACl) and ethylene glycol served as a nonvolatile medium for a variety of monomers, including methyl methacrylate, methyl acrylate, dimethylacrylamide, and styrene. We first employed the polymerization-through pathway to overcome oxygen inhibition in an open-to-air environment using methyl methacrylate as the model compound. The photoiniferter polymerization using trithiocarbonates as the chain transfer agent (CTA) in DESs exhibited enhanced polymerization rates and achieved a narrow molecular weight distribution. Interestingly, even dithiobenzoate, the CTA with low efficiency for photoiniferter polymerization, exhibited a nearly 4.5-fold increase in the apparent polymerization rate constants when compared to the reaction in dimethyl sulfoxide. Moreover, the stability of the CTAs was increased in DESs for efficient control of molecular weight distribution and preservation of functional chain ends. We then surveyed photocatalysts for photoelectron/energy transfer (PET) RAFT polymerization and found that eosin Y was compatible with DESs. The PET-RAFT polymerization using dithiobenzoate in DESs showed even higher polymerization rates than the photoiniferter polymerization and enabled the polymerization under natural sunlight. Besides methyl methacrylate, other monomers also exhibited an increased polymerization rate in DESs, comparable to reactions in ionic liquids. These results suggest that DESs are effective and green media to facilitate photo-induced RAFT polymerization without additives or tedious degassing processes.

Some thermodynamic properties and computational study of DESs (choline chloride/ethylene glycol and choline chloride/malonic acid) in lithium nitrate + propylene carbonate solutions at T = 298.15 K

Deep eutectic solvents (DESs) with propylene carbonate represent an appealing alternative for organic solvents and ionic liquids to dissolve lithium salts. The present research reports the effect of deep eutectic solvents {DESs (choline chloride/ethylene glycol with the molar ratio of 1.00:2.00) and (choline chloride/malonic acid with the molar ratio of 1.00:1.00) on the thermodynamic and transport properties of solutions of lithium nitrate (LiNO3) in propylene carbonate (PC). To evaluate solute–solvent interactions in the above systems first the volumetric, ultrasonic, and viscometric properties were studied. For this purpose, the density (d), speed of sound (C) and viscosity (η) were measured for the binary solutions of (LiNO3 + PC) and quaternary solutions containing (LiNO3 + PC) and DES in different mass fraction of, w = (0.05, 0.010, 0.015 and 0.020), at 298.15 K under ambient pressure. The measured data were used for calculation of the apparent molar volume (Vφ), standard partial molar volume (Vφ0), apparent molar isentropic compressibility (κϕ), partial molar isentropic compressibility (κφ0), partial molar volumes of transfer (ΔtrVφ0) and viscosity B-coefficient of (LiNO3 + PC + DES) solutions. Then, to evaluate the interaction energies, the density functional theory (DFT) of LiNO3 with DESs in PC has also been studied. The thermodynamic and transport investigations indicated that the choline chloride/ethylene glycol interactions are more favorable than choline chloride/malonic acid with LiNO3 in the presence of PC. Generally, the additions of these DESs on the solution of LiNO3 + PC lead to enhancing of the solute–solvent interactions. Also, the DFT results revealed that the interaction between the ChCl/EG with LiNO3 in PC is stronger than ChCl/MA with LiNO3 in PC confirming the result deduced from our experimental studies.

Salting- in effect of deep eutectic solvents on the aqueous solutions of D-glucose by using isopiestic method

In this work, the salting-in effect of some deep eutectic solvents (DESs) based on choline chloride on the aqueous solutions of D-glucose using the vapor–liquid equilibrium (VLE) data were investigated. The water activity data were obtained precisely using an improved isopiestic method and correlated with Wilson, e-NRTL, and UNIQUAC models. Also, the Hansen solubility parameters were calculated to predict the selection of appropriate solvent system. The e-NRTL model was employed to calculate activity coefficient, and the Gibbs free energies of transfer of D-glucose from water to aqueous DES solutions. Isoactivity lines of water in all systems show a large positive deviation from the linear isopistical relation (Stokes-Robinson's Zdanovskii law), which is due to the salting-in effect. The results indicate that the salting-in effect is greater in the presence of glycerol based DES and show strong interactions between D-glucose and the DES and is favorable.

The effect of silica modified by deep eutectic solvents on the properties of nature rubber/silica composites

The effect of deep eutectic solvent (DES) modified silica on the properties of nature rubber (NR) composites were investigated. The DES is an environment-friendly and low-cost solvent, which was prepared by mixing choline chloride and urea in a 1:2 molar ratio. The NR composites filled with DES modified silica were prepared and the properties were tested. The interaction between the DES and silica were characterized by Fourier transform infrared spectroscopy (FTIR), the interaction between silica and silica were tested by differential scanning calorimetry (DSC). The dynamic properties, such as rolling resistance and wet skid resistance, and were tested by dynamic mechanical analysis (DMA). Morphologies of the composites were characterized by scanning electron microscopy (SEM). The results indicate that the DES can interact with silica by hydrogen bond to improve the compatibility between the rubber and silica. When the content of DES was 3 phr, the tensile strength, modulus at 300%, tear strength, and the crosslinking density of the composites was increased. At the same time, the proper content of DES can reduce the rolling resistance of the vulcanized rubber while maintaining good wet skid resistance.

Deep eutectic solvents improve the stability of forsythoside A

AbstractForsythoside A is used as the main chemical marker for quality control of Forsythia suspensa (Thunb.) Vahl (F. suspensa, Lianqiao in Chinese) fruits and leaves. The hydrolysis of forsythoside A at high temperature and effects of deep eutectic solvents (DESs) on stability of forsythoside A were studied in the article. Forsythoside A, I, and H may be directly converted into each other at high temperature. With more heating time, they are gradually decomposed into smaller molecular compounds. High temperature, alkaline conditions, high humidity, the oxidant, and light drastically destroyed stability of forsythoside A, while acidic conditions and the antioxidant protected it. Compared with water and alcohol solvents, DESs improved effectively stability of forsythoside A due to the formation of hydrogen bonds between DESs and forsythoside A. Our research preliminarily uncovered the converting mechanism of forsythoside A and confirmed that DES improved the stability of forsythoside A.

Ultrafast Lignin Extraction from Unusual Mediterranean Lignocellulosic Residues.

Pretreatment is still the most expensive step in lignocellulosic biorefinery processes. It must be made cost-effective by minimizing chemical requirements as well as power and heat consumption and by using environment-friendly solvents. Deep eutectic solvents (DESs) are key, green, and low-cost solvents in sustainable biorefineries. They are transparent mixtures characterized by low freezing points resulting from at least one hydrogen bond donor and one hydrogen bond acceptor. Although DESs are promising solvents, it is necessary to combine them with an economic heating technology, such as microwave irradiation, for competitive profitability. Microwave irradiation is a promising strategy to shorten the heating time and boost fractionation because it can rapidly attain the appropriate temperature. The aim of this study was to develop a one-step, rapid method for biomass fractionation and lignin extraction using a low-cost and biodegradable solvent. In this study, a microwave-assisted DES pretreatment was conducted for 60 s at 800 W, using three kinds of DESs. The DES mixtures were facilely prepared from choline chloride (ChCl) and three hydrogen-bond donors (HBDs): a monocarboxylic acid (lactic acid), a dicarboxylic acid (oxalic acid), and urea. This pretreatment was used for biomass fractionation and lignin recovery from marine residues (Posidonia leaves and aegagropile), agri-food byproducts (almond shells and olive pomace), forest residues (pinecones), and perennial lignocellulosic grasses (Stipa tenacissima). Further analyses were conducted to determine the yield, purity, and molecular weight distribution of the recovered lignin. In addition, the effect of DESs on the chemical functional groups in the extracted lignin was determined by Fourier-transform infrared (FTIR) spectroscopy. The results indicate that the ChCl-oxalic acid mixture affords the highest lignin purity and the lowest yield. The present study demonstrates that the DES-microwave process is an ultrafast, efficient, and cost-competitive technology for lignocellulosic biomass fractionation.

Effect of deep eutectic solvent’s characteristics on extraction and bioactivity of polyphenols from Sapodilla pulp

In the present study, a sustainable and efficient deep eutectic solvent (DES)-based ultrasound-assisted extraction method for Sapodilla pulp polyphenols was developed. Seven different DESs prepared using carboxylic acid, polyol and amide were evaluated and compared with an aqueous-organic solvent mixture- acetone–water (50%)- the control used in this study. Low pH and high polarity markedly enhanced the recovery of the polyphenols in acid-based DESs. The highest yield was obtained with oxaline, followed by maloline and laline, as the presence of three OH groups considerably retarded the interaction between DES and target compounds, enhanced the viscosity and reduced the availability of H-bonding sites in glyceline and maline. Although the extraction rate was considerably slower in highly viscous DESs, the time required to attain the equilibrium was only marginally higher for oxaline and maloline than the acetone–water mixture. Reduced air incorporation due to high viscosity and strong H-bonding with DESs also substantially enhanced the storage stability of released antioxidants in DES. The low pH of carboxylic acid constituents and innate toxicity of urea at high concentration were responsible for high antimicrobial activity of acid, and amide-based DES extracts against Aspergillus and Bacillus. However, cell lysis and enzyme inhibitory properties of polyphenols were responsible for antimicrobial activities of polyol-based DESs and organic solvent-based extracts. However, the ability of fungi to metabolize the substrates effectively reduced DESs’ efficiency against the organism compared to bacteria. Therefore, these solvents have great potential as possible alternatives to conventional solvents health-related areas, such as food and medicines.

Effect of deep eutectic solvents based on choline chloride on the thermodynamic and transport properties of D-fructose in aqueous solution

In this work, the effect of some deep eutectic solvents (DESs) based on choline chloride on the thermodynamic and transport properties of D-fructose in aqueous solutions was investigated. Using the vapor-liquid equilibrium (VLE) data, water activity (aw), osmotic coefficient and vapor pressure data were obtained. The performance of different local composition models such as Wilson, e-NRTL, and UNIQUAC for correlating of these data have been examined. The calculated negative values of Gibbs free energies of transfer (ΔGtri) indicate favorable interaction of DESs with D-fructose. Further, the standard partial molar volumes Vφ0, partial molar isentropic compressibility Kφ0, viscosity B-coefficient and molar refractions RD for the solutions have been calculated from the measured density and speed of sound, viscosity and refractive index data at T = (288.15 to 318.15) K. Interaction volume Vint and cavity volume Vcav have been computed from scaled particle theory (SPT) to probe solute-solvent interactions. The viscosity B-coefficients was used to discuss structure-making tendency of the solutions studied.

Study on improvement of chiral separation of capillary electrophoresis based on cyclodextrin by deep eutectic solvents

For the first time, the mechanism of deep eutectic solvents (DESs) improving chiral separation by capillary electrophoresis has been studied. The capillary electrophoresis chiral separation has been improved by using DESs as the auxiliary additive. Taking tropicamide, homatropine hydrochloride, ofloxacin, atenolol and propranolol hydrochloride as model chiral separation targets and cyclodextrin (CD) as the chiral selector, and the effects of DESs on the chiral separation resolution were investigated on the basis of optimized conditions. The results of fluorescence spectrophotometry and non-aqueous capillary electrophoresis showed that DESs can improve the resolution of the enantiomers, and the coordination mechanism of DESs was also explored. After DESs were added, the resolution of the above enantiomers increased from 1.26, 1.70, 5.10, 1.90, 2.02 to 3.02, 4.10, 6.86, 2.84 and 5.51 respectively, and the binding constant of CD with propranolol hydrochloride increased from 23 M−1 to 142 M−1. The results showed that DESs is an effective auxiliary additive to improve the separation efficiency of capillary electrophoresis with CD as a basic chiral additive.

Application of Deep Eutectic Solvents and Ionic Liquids in the Extraction of Catechins from Tea.

This work aimed to comprehensively evaluate the potential and effectiveness of deep eutectic solvents (DESs) in the extraction of seven catechins from various tea samples. Different combinations of DES were used, consisting of Girard’s reagent T (GrT) in various mixing ratios with organic acids and choline chloride. The yields of the DES extractions were compared with those from ionic liquids and conventional solvent. DES contained malic acid, as the hydrogen bond donors showed a good solubility of catechins with different polarities. In the second part of the study, a solid-phase extraction (SPE) method was applied to the extraction of catechins from tea infusions. The method was applied to the determination of selected catechins in tea leaves and tea infusions. Furthermore, we demonstrated that the proposed procedure works well in the simultaneous monitoring of these polyphenols, which makes it a useful tool in the quality control of tea.

Tailoring the morphology of poly(high internal phase emulsions) synthesized by using deep eutectic solvents

Abstract High internal phase emulsions (HIPEs) are among complex biphasic fluids that expand on the traditional emulsion compositions, for instance, for the preparation of macroporous polymers by emulsion templating. The use of deep eutectic solvents (DESs) as the nonaqueous internal phase of HIPEs allows expanding the conditions at which polymerizations are typically carried out in aqueous HIPEs. Herein, the properties of polystyrene macroporous polymers were studied by polymerizing DES-in-oil HIPEs using choline chloride-based DESs as the internal phase. The effect of DESs’ composition – with amide, alcohol, and carboxylic acid as hydrogen bond donors – and the homogenization method used for the HIPE preparation – vortexing versus high-speed homogenizer – was studied. The stability and droplet size of HIPE precursor, as well as the macroporous structure and the mechanical properties of the synthesized polyHIPEs, are discussed.

Extractive desulfurization of fuels using diglycol based deep eutectic solvents

Abstract In this work, the effect of Deep Eutectic Solvents (DESs) on sulfur extraction of organo-sulfur compounds was investigated. Different DESs were prepared using a common hydrogen bond donor, Diglycol, and different hydrogen bond acceptors. The effects of experiment variables such as temperature, DESs/feed ratio, and the time on desulfurization efficiency of different organo-sulfur compounds were also studied. Results show that Tetra butyl ammonium bromide based DES showed relatively higher sulfur removal capabilities (Dibenzothiophene (DBT): −92 %, 2- Methylthiophene (2-MT): −86 % and Thiophene (T): −71 %)) as compared to other DESs. Also, all DESs have higher DBT extraction efficiency followed by 2-MT and T. Further, non-random two liquids (NRTL) thermodynamic model was employed to model liquid-liquid equilibrium.

Deep Eutectic Supramolecular Polymers: Bulk Supramolecular Materials

AbstractApplication of new strategies for supramolecular self‐assembly can significantly impact the properties and/or functions of supramolecular polymers. To realize a facial strategy for the development of solvent‐free supramolecular polymers in bulk, “deep eutectic solvents” were employed. Cyclodextrins and natural acids were used to prepare deep eutectic supramolecular polymers (DESPs). Deep eutectic solvents have special characteristics that endow DESPs with unique macroscopic properties and excellent processability. DESPs exhibit supramolecular adhesion and temperature‐dependent behavior originating from the combined effects of deep eutectic solvents and supramolecular polymerization. Because DESPs are solvent‐free and display interesting macroscopic properties, they have potential as new adaptive materials.