Deep Eutectic Mixture Research Articles

Formation of Aqueous Two‐Phase Systems Using Potassium Salt and Deep Eutectic Mixtures for Extraction of Proteins

AbstractLiquid‐liquid extraction such as an aqueous two‐phase system (ATPS) is considered a promising method in the biotechnology field for extraction of biomolecules. The binary mixture of polyethylene glycol (PEG)/salt is the most common ATPS. The ability of eutectic mixture‐based ATPS to fractionate protein macromolecules remains not well understood. Here, the role of hydrogen bond donors (HBDs) in eutectic mixtures was investigated in relation to the phase formation ability and extraction efficiency of protein. Both potassium salt and an eutectic combination were used to prepare the ATPSs. Choline chloride/urea aqueous two‐phase separation proved to be the most effective method for protein extraction. The creation of a two‐phase system and the efficiency with which a protein can be extracted from a crude solution are both affected by the choice of HBD.

Screening of deep eutectic solvent mixtures for treating empty fruit bunches to obtain cellulose nanofiber

Cellulose nanofibers (CNFs) are attractive reinforcing materials for advanced nanocomposites due to their uniqueness characteristics. The study aims to extract CNFs from empty fruit bunches (EFB) using different deep eutectic solvent (DES) mixtures to determine which DES mixture produces the highest CNFs yield. Various DES mixtures, e.g. (i) choline chloride-oxalic acid dehydrates (ChCl-OAD); (ii) choline chloride-malic acid (ChCl-MA); (iii) choline chloride-citric acid (ChCl-CA); and (iv) choline chloride-acetic acid (ChCl-AA) was used as extraction solvent for CNFs. ChCl-OAD is the most effective DES mixture, producing the highest CNFs at 45.6%. The produced CNFs were nanosized, with an average diameter of 27.8 nm and degree of crystallinity of 66.7%. This research may act as foundation for the large-scale, high-yield production of nanocellulose using DES.

Merging Proline:Xylitol Eutectic Solvent in Crosslinked Chitosan Pervaporation Membranes for Enhanced Water Permeation in Dehydrating Ethanol.

The scope of this research aims at merging a new deep eutectic mixture (DES) into a biopolymer-based membrane for a pervaporation application in dehydrating ethanol. Herein, an L-proline:xylitol (at 5:1) eutectic mixture was successfully synthesized and blended with chitosan (CS). A complete characterization of the hybrid membranes, in terms of morphology, solvent uptake, and hydrophilicity, has been conducted. As part of their applicability, the blended membranes were assayed for their ability to separate water from ethanolic solutions by means of pervaporation. At the highest temperature (50 °C), a water permeation of ca. 0.46 kg m-2 h-1 was acquired, representing a higher permeation than the pristine CS membranes (ca. 0.37 kg m-2 h-1). Therefore, CS membranes demonstrated an enhanced water permeation thanks to their blending with the hydrophilic L-proline:xylitol agent, making these membranes a good candidate for other separations containing polar solvents.

Comparison of the acidity of systems based on choline chloride and lactic acid

The acidity/alkalinity of solvents is a parameter that affects their use and at the same time, it is a basic property of solvents or systems. In the case of new types of deep eutectic solvent-like mixtures (DES-like mixtures), their use is questionable, considering that they do not correctly describe the acidity/alkalinity of the solutions. The aim of this work was to characterize the acidity of systems containing choline chloride (ChCl) and lactic acid (LacA) in molar ratios of 1:1 to 1:9 with different water content, and to determine the acidity by titration and express it using milliequivalents of acids per kilogram of solvent (the first time). The prepared DES-like mixtures had an acidity of 3377 ± 63 meq/kg for ChCl/LacA (1:1) up to 7511 ± 28 meq/kg for ChCl/LacA (1:9). The acidity of these solvent systems increased with an increasing ratio. ChCl solution showed an acidity value of only 0.175 ± 0.05 meq/kg. In addition, it was found that acidity has completely additivity properties in these systems.

Delignification of Halophyte Atriplex crassifolia by Green Recyclable Deep Eutectic Solvents for Enhanced Production of Biogas

Deep eutectic solvents (DESs) have upgraded the practices of valorizing lignocellulosic feedstock by lessening biomass recalcitrance through delignification in precise and economical manner. In this study, the influence of a series of deep eutectic mixtures was evaluated on the halophyte Atriplex crassifolia for achieving elevated biogas production. Initially, the biomass was pretreated via several DESs with varying hydrogen bond donors (HBDs) including carboxylic acids, amine/amide, and polyols/glycols. DES composed of choline chloride (ChCl) and lactic acid (LA) evidenced as the most effective solvent in achieving high lignin removal rates and was further optimized by evaluating the parameters of molar ratio of DES components, solid-to-liquid ratio, and solvent addition. A maximum delignification value of 89.5% was achieved by 15% diluted ChCl: LA (1:2) DES at a biomass loading of 1:15. The solubilization rate of diluted ChCl: LA was also raised up to 38%. FT-IR analysis revealed significant lignin elimination from ChCl: LA pretreated substrates. Moreover, ≥88% of ChCl: LA DES was recovered after up to three pretreatment cycles, retaining ≥85% delignification efficiency. Fresh DES-pretreated Atriplex crassifolia recorded 32.2 mL/g of biogas production yield due to increased cellulosic content. The findings validated Atriplex crassifolia as an efficient feedstock for biogas production and confirmed the affectivity of ChCl: LA pretreatment in eliminating the lignin barrier, ultimately making cellulosic sugars readily biodegradable and highly accessible for anaerobic microorganisms.

Fabrication of photochromic and electrochromic (PVP-am)/WO3/MoO3 hydrogel composites and glass films with programmable shapes

Recently, the fabrication of functional and stimuli-responsive hydrogels using deep eutectic solvent derivatives is gaining tremendous scientific recognition owing to their unique self-switching properties. In this study, perfluorinated deep eutectic mixtures were prepared as the template for the synthesis of WO3/MoO3 composites. The metal oxide-based composites were further employed as a chemical crosslinking agent for the polymerization of polyvinyl pyrrolidine (PVP) and acrylamide (Am), for the construction of (PVP-Am)/WO3/MoO3 hydrogel composites. The hydrogels displayed unique morphologies and mechanical properties. The hydrophilic nature of hydrogels as well as the high concentration of dispersed WO3/MoO3 composites in the polymer network contributes to their photochromic activity and allows an immediate coloration upon exposure to light at a short time. Howbeit, the low concentration of the dispersed WO3/MoO3 composites in the dry glass membrane is responsible for the blue coloration and an extended time of photochromic response. In addition, the electrochromic behavior of the hydrogel composites displayed a strong quasi-rectangular shape potential window as well as a well-defined redox cyclic voltammetry curve when exposed to high voltage. This could be due to the photoredox property of the WO3/MoO3 composites responsible for charge transfer between the different oxidation states.

Selective Extraction of Antioxidants by Formation of a Deep Eutectic Mixture through Mechanical Mixing

Extraction of active compounds from natural materials is commonly used to produce a diverse range of ingredients, nutrients, drugs, flavors, and fragrances. While solvent-based approaches are standard for these extraction procedures, large solvent volumes, greenhouse gas emission (due to atmospheric release of volatile organic compounds), and large energy requirements are significant issues. Here, we describe a novel process wherein a mechanical action is applied to a solid-state mixture comprising a quaternary ammonium salt and a biological material containing active molecules to form a deep eutectic mixture. It is first shown that eutectic mixtures can be formed for a wide range of naturally occurring compounds. Selective extraction of these compounds from natural products is then demonstrated using rosemary leaves with three different quaternary ammonium salts. The eutectic mixture formed is purified by liquid/liquid extraction using an oily phase to concentrate the active constituents in the deep eutectic phase. The resulting natural extracts are shown to exhibit high antioxidant activities, which were measured using the conjugated autoxidizable triene (CAT) and the oxygen radical absorbance capacity (ORAC) assays.

Application of a deep eutectic mixture and ionic liquid as carriers in polymer adsorptive membranes for removal of copper(II) and zinc(II) ions from computer scrap leachates

Application of a deep eutectic mixture and ionic liquid as carriers in polymer adsorptive membranes for removal of copper(II) and zinc(II) ions from computer scrap leachates

Facile synthesis of triazolo/benzazolo[2,1-b]quinazolinone derivatives catalyzed by a new deep eutectic mixture based on glucose, pregabalin and urea.

In this study, a novel natural deep eutectic solvent was prepared from glucose, pregabalin, and urea. The prepared solvent was identified using a variety of techniques, including Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), differential thermal analysis (DTA), and refractive index measurements (RI). The prepared deep eutectic solvent was then utilized for the one-pot synthesis of quinazolinone derivatives. The yields of the product obtained with and without the catalyst were determined, providing insights into the catalytic efficiency of the system. This protocol offers several advantages, including mild reaction conditions, easy reagent preparation, a green process, short reaction times (2-60 min), high yields (80-99%), and a straightforward procedure with the possibility of catalyst reusability.

Development of salt-induced homogenous liquid-liquid extraction based on ternary deep eutectic solvent coupled with dispersive liquid-liquid microextraction for the determination of heavy metals in honey

In this work, a homogenous liquid–liquid extraction method was combined with dispersive liquid–liquid microextraction and utilized for the extraction of Co, Zn, Ni, Cu, Pb, and Tl from honey samples before their determination by inductively coupled plasma-atomic emission spectrometry. For this purpose, firstly, diluted honey solution was transferred into a glass test tube and mixed with a few milliliters of a mixture of n-butanol and choline chloride: menthol: p-aminophenol deep eutectic solvent. A homogenous solution was obtained. After that an appropriate amount of sodium chloride was added into the solution and sonicated for 6 min. During this step, the homogenous solution was broken and the mixture of n-butanol and the deep eutectic solvent mixture was collected on top of the solution. The supernatant phase was removed and quickly injected into deionized water. After centrifugation, the collected phase at the bottom of the tube was injected into the determination system. Under the optimum situations, low limits of detection (0.24–0.74 ng g–1) and quantification (0.79–2.46 ng g–1), high extraction recoveries (80–92%), and good repeatability (relative standard deviations equal to or less than 3.6% and 3.9% for intra– and inter-day precisions, respectively) were acquired. Finally, the offered method was employed for determination of the studied heavy metals in various honey samples marketed in Tabriz city, Iran.

Summarizing the Effect of Acidity and Water Content of Deep Eutectic Solvent-like Mixtures—A Review

Deep eutectic solvent-like (DES-like) mixtures re-emerged in green chemistry nineteen years ago and yet have led to a large number of publications covering different research areas and different application industries. DES-like mixtures are considered a special class of green solvents because of their unique properties, such as high solubilization ability, remarkable biocompatibility, low production cost, low volatility, relatively simple synthesis methods, and considerable stability. Several studies have been published that analyze the effect of acidity/alkalinity and water content in DES-like mixtures on their physicochemical properties and behavior. This work summarizes the characterization of green solvents and, subsequently, the influence of various factors on the resulting pH values of green solvent systems. Part of this work describes the influence of water content in DES-like mixtures on their physical and chemical properties. The acidity/alkalinity effect is very important for green solvent applications, and it has the main impact on chemical reactions. As the temperature increases, the pH of DES-like mixtures decreases linearly. The type of hydrogen bond donors has been shown to have an important effect on the acidity of DES-like mixtures. The water content also affects their properties (polarity, solubilization capacity of DES-like mixtures).

Extraction of Flavonoids from Koenigia weyrichii Using a Deep Eutectic Mixture of Choline Chloride + Glycerine

Extraction of Flavonoids from Koenigia weyrichii Using a Deep Eutectic Mixture of Choline Chloride + Glycerine

Synthesis of benzopyranophenazine derivatives in the presence of Glycerol: Urea: NH4Cl mixture

Deep eutectic solvents have become attractive alternatives to conventional solvents due to their interesting characteristics such as physicochemical properties, low cost of components, easiness to prepare, low toxicity, bio renewability and biodegradability. To make the deep eutectic mixture more cost effective and renewable, carbohydrate was linked with the deep eutectic mixture, since, carbohydrates are the most significant renewable compound. In this work, we have used low melting mixtures comprised of carbohydrates to create reaction media for organic transformations. The physical properties such as density, viscosity, acidity, refractive index, surface tension, solubility, glass transition temperature, and thermal stability of the mixture were studied. Glycerol: Urea: NH4Cl low melting mixture was employed as reaction medium and catalyst for the effective synthesis of Benzopyranophenazine carbonitrile which made the reaction cost effective, safe and reduced the use of organic solvent. The reaction between o-phenylenediamine, 2-hydroxy -1,4 naphthoquinone, malononitrile and aldehyde was performed effectively with good to excellent yields.

Extraction of Emerging Contaminants from Environmental Waters and Urine by Dispersive Liquid-Liquid Microextraction with Solidification of the Floating Organic Droplet Using Fenchol:Acetic Acid Deep Eutectic Mixtures.

In this work, several eutectic mixtures formed by fenchol and acetic acid at seven molar ratios (between 4:1 and 1:4) were characterized and studied for the first time for their possible application as extraction solvents in dispersive liquid-liquid microextraction based on the solidification of the floating organic droplet (DLLME-SFO). A group of 13 emerging contaminants (gemfibrozil, bisphenol F, bisphenol A, 17β-estradiol, testosterone, estrone, levonorgestrel, 4-tert-octylphenol, butyl benzyl phthalate, dibutyl phthalate, 4-octylphenol, 4-nonylphenol, and dihexyl phthalate) was selected and determined by liquid chromatography with ultraviolet and tandem mass spectrometry detection. Among the studied mixtures, only those of 2:1 and 1:1 provided the suitable features from an operational and repeatability point of view, suggesting that several eutectic mixtures of the same components may also provide similar results. Once the extraction conditions of both mixtures were optimized, the method was applied to the extraction of sea water, urine, and wastewater at different concentration levels, allowing the achievement of absolute recovery values between 49 and 100% for most analytes with relative standard deviation values below 19%. In addition, several samples of each type were analyzed, finding bisphenol A and gemfibrozil in some of them. The greenness of the method was also evaluated using the AGREEprep metric. The DLLME-SFO procedure was found to be very simple, quick, and effective and with a good sample throughput.

External Heavy-Atom Activated Phosphorescence of Organic Luminophores in a Rigid Fluid Matrix

Growing attention has been paid to pure organic room-temperature phosphorescence (RTP). Although an insufficient population and fast nonradiative decay of triplet excitons are avoided in recent endeavors, complicated synthesis and limited universality still hinder its development. Further, fluid RTP materials are more difficult to design because of faster nonradiative relaxation. Herein, a deep eutectic mixture of glucose and choline, a stable supercooled liquid at room temperature, is employed as a matrix. Direct transformation from commercial fluorescent dyes to RTP fluid is realized by doping without modifications. The excited triplet states are generated by an external heavy atom, while the rigid noncovalent network stabilizes them with both functions intrinsic to the liquid matrix. Modulation of matrix components also results in nearly white light emission of a single dye. This study presents a general strategy to design fluid RTP materials starting from the vast library of fluorophores.

Modifiers based on deep eutectic mixtures: A case study for the extraction of anthocyanins from black bean hulls using high pressure fluid technology

Deep eutectic solvents (DES) were selected as water modifiers to perform the subcritical water extraction (SWE), aiming at the selective extraction of anthocyanins from black beans hulls. To identify an efficient and environmentally friendly solvent, the COSMO-RS model was used, which was able to predict the affinities of individual anthocyanins in different DES modifiers in water. In this case, the combination of choline chloride and citric acid as water modifiers was the most promising solvent. Temperature, flow rate, and percentage of DES in subcritical water extraction were optimized. The best anthocyanin extraction (3 mg C3G g−1) was obtained at 90 °C, 5 mL min−1, and 1 % DES, a threefold increase compared to pure water. Therefore, the implementation of SWE with DES opens the possibility of increasing the extraction efficiency, meeting the requirements of a green and sustainable approach for applying extracts with anthocyanins as natural colorants.

Appraisal of adsorptive potential of novel one-walled meso-phenylboronic acid functionalized calix[4]pyrrole for liquid phase sequestration of paracetamol

It is critical to design an ecological and economically benign adsorbent for the decontamination of micropollutants from the aquatic realm. Supramolecular functional materials have garnered remarkable attention in recent times owing to their various potential applications. A supramolecular meso-phenylboronic acid functionalized calix[4]pyrrole (mPBA-C4P) was fabricated via a green synthetic approach utilizing a deep eutectic mixture of N,Ń-dimethylurea and L-(+)-tartaric acid, which was subsequently applied as an advanced adsorbent for paracetamol (PC) removal from aqueous phase. The characterization of mPBA-C4P was accomplished with NMR (1H and 13C), FTIR, high-resolution mass spectrometry (HRMS), SEM-EDX, Brunauer-Emmet-Teller (BET) analysis, and elemental mapping. The mPBA-C4P unveiled a commendable adsorption characteristics adsorbing > 92% PC within 20 min from simulated water having 30 mg L−1 PC concentration. The isotherm modeling inferred the Freundlich model to appropriate the equilibrium data, with high Langmuir adsorption capacity (479.30 mg g−1 at 298 K). The ΔH° (–53.98 kJ mol−1) along with a drop in adsorption capacity with temperature implied the process to be exothermic. The kinetics was in accord with the pseudo-second order model specifying chemisorption mechanism. However, the bt (2.56 kJ mol−1) and E (1.08 kJ mol−1) implied physical adsorption, suggesting, thereby, that the adsorption of PC occurred via concurrent physisorption and chemisorption. The mPBA-C4P maintained a decent removal rate after five consecutive adsorption–desorption cycles speculating its good reusability and practicality. Salting out effect was responsible for the enhancement in PC confiscation in presence of different ions. Based on FTIR spectral data, pH, isotherm, kinetic, thermodynamic and ionic studies, the proposed mechanism governing the uptake of PC by mPBA-C4P involved hydrogen bonding, π-π, n-π, anion-π and cation-π interactions, respectively. These findings indicated that mPBA-C4P could be weighed as a potentially superior adsorbent for alleviating paracetamol-laden waters.

A synergetic green approach for enhanced CO2 capture in protic deep eutectic mixtures – Kinetics and Henry’s solubility determination

Anthropogenic CO2 emitted by burning fossil fuels have been the most prevalent cause of global warming. Recent investigations on the use of liquid scrubbers as absorbents have been carried out widely. In the current study, the ability of protic deep eutectic solvents (pNADES) to act as liquid scrubbers is being investigated. Sixteen pNADESs formed with amino acids as Hydrogen bond acceptors (HBA) and fatty acids as Hydrogen bond donors (HBD) respectively. CO2 solubility in pNADES was recorded as a function of pressure (0 – 2.5 MPa) and temperature (298.15 – 323.15 K). The highest solubility was exhibited by Histidine and Decanoic acid (H: DA) pNADES (0.45 mg CO 2/g pNADES) at 1.5 MPa and 313.15 K. Henry’s solubility for H: DA was noted to be (3.06 mol of CO 2 /mol pNADES) guaranteeing effective absorption. Kinetics of absorption recyclability of the solvent shows moderate reutilization (86 %) even after 3 absorption cycles.

Thermo-responsive hydrogel with deep eutectic mixture co-monomer as drawing agent for forward osmosis

Deep eutectic mixture (DEM) and N-isopropylacrylamide (NIPAM) were co-polymerized as thermo-responsive P(NIPAM-co-DEM) hydrogel drawing agents for forward osmosis (FO). N-hexyl-N,N-dihydroxyethyl-N-methylammonium chloride–acrylic acid ([DHEA]Cl-AA) DEM is non-toxic and highly conductive due to its ionic (R4N+, Cl−) and hydrophilic (-OH, -C=O) groups. Addition of DEM at different contents (0–7.5 wt%) afforded P(NIPAM-co-DEM) with wide open pores as excellent water channels during water absorption. Their critical temperatures ranged Tc = 34.7–51.4 °C. At T < Tc, P(NIPAM-co-DEM) attained equilibrium swelling ratios = 32–43 (vs. 19 for PNIPAM), highlighting the advantage of DEM for enhanced water absorption. Heating the hydrogels at T > Tc resulted in 87.6–96 % dewatering efficiencies. Among the fabricated hydrogels, P(NIPAM-co-DEM) with 5 wt% DEM exhibited the highest water uptake and dewatering efficiency at moderate Tc. It achieved the highest FO water flux (initial Jv = 2.38 LMH in DI water feed). P(NIPAM-co-DEM) with 5 wt% DEM effectively and consistently desalinated low salinity water (2000 mg L−1 NaCl, Jv = 1.81 LMH) and treated domestic wastewater (Jv = 1.90 LMH) at T = 25 °C in cycled operations via efficient water recovery T = 45 °C and hydrogel drying via solar irradiation (1 kW m−2 for 1.5 h). Overall results demonstrate the potential of deep eutectic mixtures for the development of hydrogels as effective FO drawing agents.

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.