Formation Of Deep Eutectic Solvents Research Articles

The properties of Chinese Baijiu distilled spent grain-derived hydrochar: effect of in situ deep eutectic solvents formation during hydrothermal carbonization

Distilled spend grain with rice husk (DSGH), a by-product of Chinese Baijiu, can be used as a solid fuel after hydrothermal carbonization (HTC) treatment. To enhance carbonization during HTC, a new strategy based on the addition of lactic acid to DSGH and AlCl3 is proposed for the in situ formation of deep eutectic solvents (DESs). The results show that in situ DES formation significantly enhanced the recovery of organic matter, thereby increasing the yield of hydrochar. Moreover, in situ DES formation effectively hindered the reaction between NH4+ and polysaccharides. Additionally, DES disrupted the protein structure in DSGHP, thereby intensifying protein hydrolysis and deamination. Furthermore, the DES altered the HTC process of the DSGHP. In summary, the incorporation of in situ DESs significantly influenced the HTC of DSGHP, leading to notable improvements in the recovery and quality of hydrochar. This study provides valuable insights into the potential of DESs in enhancing HTC processes, particularly for biomass such as DSGHP.

An integrated method for rapid extraction of fluorescent whitening agents from selected cosmetics by in situ formation of deep eutectic solvent

A novel extraction methodology was developed based on deep eutectic solvent (DES) in situ formation. The solvent was synthesized from a binary mixture of L-cysteine, functioning as a hydrogen bond acceptor, and 2-methylphenol, serving as a hydrogen bond donor. The DES’s inherent molecular structures and extensive hydrogen bonding networks were characterized using the Fourier-transform infrared spectroscopy (FT-IR), while its hydrophobic nature was assessed by determining molecular polarity. Its extraction efficiency was demonstrated through the extraction of fluorescent whitening agents (FWAs) in cosmetic products, acting as a model analytical application. This was accomplished using vortex-assisted emulsification solid–liquid extraction (SLE) method, followed by high-performance liquid chromatography-fluorescence detection. Response surface methodology was employed to optimize extraction conditions in a multivariate experimental design. This approach streamlined the multi-operation extraction process via ingeniously integrating extraction and clean-up into a single step, resulting in significant reductions in extraction time required and high sample throughputs of approximately 40 samples per hour. The methodology was validated and exhibited excellent linearity in concentration ranges of 0.01–24 mg/L for five FWAs and 0.01–40 mg/L for other three FWAs, with correlation coefficients (r) ranging from 0.9985 to 1.000. The limits of detection and quantification were in the range of 0.03–0.26 mg kg−1 and 0.10–0.87 mg kg−1, respectively. The reliability and practicality of the proposed method were affirmed by quantifying eight FWAs in ninety-four commercially available facial masks and whitening creams, yielding recoveries values between 90.0 % and 106.0 % with relative standard deviations (RSDs) of 1.0–4.3 %. Inorganic ions and organic compounds present in the samples had minimal impact on FWAs detection following sample pre-treatment. This procedure showcased exceptional extraction capabilities towards a diverse array of FWAs with the aid of multiple interactions, suggesting significant potential for increasing sample throughput while reducing organic solvent and material consumptions compared with conventional SLE methods. The low-toxicity DES is an excellent alternative to traditional extractants typically applied to SLE techniques.

Highly efficient separation of phenol with tetraethylammonium chloride-based deep eutectic solvents: Experiments and theoretical calculations

To gain more insight into the mechanism of the separation of phenols by deep eutectic solvents (DESs), four DESs: tetraethylammonium chloride (TEAC)-ethylene glycol (EG), TEAC-diethylene glycol (DEG), TEAC-triethylene glycol (TEG) and TEAC-tetraethylene glycol (TTEG) were prepared for the extraction of phenols from model oil. Experimental parameter optimization results indicated that four DESs were effective in extracting phenols, and TEAC-EG had the highest extraction efficiency (EE), with EE up to 98.95%. Subsequently, the formation mechanism of DESs and the extraction mechanism were revealed at the molecular/atomic level by quantum calculations using density functional theory (DFT). The most stable configurations, hydrogen bonding lengths, and interaction energies of DESs and corresponding systems have been calculated, and the weak interactions in the systems were visualized and further analyzed. The results showed that DESs formation were mainly due to a combined effect of hydrogen bonding and van der Waals (vdW) forces. Besides, hydrogen bonding and vdW forces between DESs and phenol were the main forces acting to extract phenol, and the hydrogen bonding within DESs was weakened when DESs interacted with phenol.

In situ formation of natural deep eutectic solvent on membrane after fat hydrolysis for lindane isomers determination in peanut paste

In this work a sample pretreatment approach assumed liquid-liquid microextraction based on the in situ formation of a hydrophobic natural deep eutectic solvent on a hydrophobic membrane impregnated with natural terpenoid was developed. The procedure included alkaline hydrolysis of a food sample containing fat to form fatty acids, which acted as precursors for the in situ formation of the deep eutectic solvent with natural terpenoid. Two processes were observed on the membrane surface: in situ formation of the hydrophobic deep eutectic solvent and liquid-liquid microextraction of the target analytes. After microextraction, the membrane containing the analytes was easily removed from the sample solution. The developed approach was applied to the separation and preconcentration of hydrophobic organochlorine pesticides (ɑ-hexachlorocyclohexane and γ-hexachlorocyclohexane) from a hydrophobic sample matrix (peanut paste), followed by their determination by gas chromatography with electron capture detection. Under optimal conditions, the limits of detection and quantification for both analytes were 0.3 and 1.0 μg kg−1, respectively. The procedure allowed the separation of fat-soluble analytes from a complex sample matrix with a high content of fat. The extraction recoveries were in the range of 93–95 %.

Application of PC‐SAFT EoS and SCFT for the modeling of thermophysical properties comprising deep eutectic solvent and alcohols

AbstractZinc (II) chloride based deep eutectic solvent (DES) were formed by mixing zinc (II) chloride with phosphoric acid. Fourier‐transform infrared spectroscopy was used to identify any possible shifts when the two compounds were assorted, and differential scanning calorimetry (SDT Q600 V20.9 Build 2D) was utilized to evaluate the formation of deep eutectic solvent. Densities, , and speed of sound, u, of [ZnCl2][phosphoric acid] 1:2.5 with methanol, ethanol, or propanol have been measured at T = (293.15, 303.15, 308.15, and 313.15) K and at atmospheric pressure. Excess molar volumes (), isentropic compressibilities (), deviation in isentropic compressibility (), and intermolecular free length () were calculated from the densities, and speed of sound, respectively. To fit the excess molar volumes and deviation in isentropic compressibilities, the Redlich–Kister smoothing polynomial was used. Also, we have used perturbed chain statistical associating fluid theory equation of state (PC‐SAFT EoS) for modeling the densities of the binary mixtures, and Schaaff's collision factor theory (SCFT) and Nomoto's relation (NR) were used for modeling the speed of sounds for the binary mixtures.

Extraction of Eugenol from Essential Oils by In Situ Formation of Deep Eutectic Solvents: A Green Recyclable Process

Extraction of Eugenol from Essential Oils by In Situ Formation of Deep Eutectic Solvents: A Green Recyclable Process

A molecular insight into formation of deep eutectic solvents and their application for the enhancement of proton transportation via graphene oxide-based proton exchange membranes

A molecular insight into formation of deep eutectic solvents and their application for the enhancement of proton transportation via graphene oxide-based proton exchange membranes

Separation of protein by formation of deep eutectic solvents using trimethylamine oxide

It is still a challenge to recover protein from discarded shrimp shells by an environmentally friendly and effective method. A method to recover proteins from shrimp shells by forming deep eutectic solvents (DESs) is reported in this study, in which trimethylamine oxide (TMAO) and proteins act as hydrogen bond acceptor and hydrogen bond donor, respectively. The optimal protein extraction conditions were optimized by single factor experiments with TMAO concentration of 7%, extraction temperature of 50 °C and extraction time of 16 h. Furthermore, it was systematically explored and verified that TMAO achieves extraction by forming hydrogen bonds with amino hydrogen atoms, peptide-bonded hydrogen atoms and carboxyl hydrogen atoms of proteins. Complementarily, the wide range of TMAO applications for protein extraction was also verified by using other internal salts and protein sources. As a non-toxic and environmentally friendly extractant, TMAO not only has great development prospects in the field of extraction, but also has great significance for realizing the virtuous cycle of resources.

The Complex Story Behind a Deep Eutectic Solvent Formation as Revealed by l-Menthol Mixtures with Butylated Hydroxytoluene Derivatives

The Complex Story Behind a Deep Eutectic Solvent Formation as Revealed by <scp>l</scp>-Menthol Mixtures with Butylated Hydroxytoluene Derivatives

Deep Eutectic Solvents with Excellent Catalytic Ability for Extractive and Oxidative Desulfurization under Room Temperature

Deep eutectic solvents (DESs) have been intensively investigated as promising green solvents for extraction combined with oxidative desulfurization (EODS) of fuel oil. However, it is still a challenge to explore the effect of hydrogen bond acceptor (HBA) and hydrogen bond donor (HBD) structure on the formation of DESs and the performance of desulfurization. In this study, exploratory density functional theory (DFT) calculation was first carried out to reveal the influence of the electron density of HBA on the preparation of DES. Then, the structures of DESs were optimized, and their interaction energy was calculated. The structure of HBA and HBD has an important effect on the formation of DES and the capacity of EODS. Under optimal conditions (30 °C, O/S = 2), the desulfurization efficiency of phenol/formic acid (Ph/FA) DES can reach as high as 99.8%. Further, the desulfurization mechanism was also investigated by experiments, characterizations, and verified DFT calculations. This study not only provides a new aspect for designing and understanding DESs but also provides a novel catalyst for efficient EODS.

Oxymatrine-fatty acid deep eutectic solvents as novel penetration enhancers for transdermal drug delivery: Formation mechanism and enhancing effect

Transdermal delivery of drugs is commonly limited by low skin permeability. The aim of the study was to synthesize deep eutectic solvents (DESs) based on oxymatrine (OMT) and fatty acids with various alkyl chain lengths (LCFAs) as novel vehicles, to solubilize the water-insoluble drug and enhance percutaneous penetration. Quercetin (QUE) was selected as a model drug. Combining differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and molecular simulations demonstrated that the formation of DESs was mediated by charge-assisted hydrogen bonding. Physicochemical properties including stability, viscosity, and solubilization capacity were also studied. Subsequently, the effect of three stable DESs on drug release and skin permeability was evaluated. The results showed that QUE was solubilized well and presented a different sustained release behavior in DESs. Meanwhile, DESs enhanced the skin permeation of OMT and QUE, which was influenced by alkyl chain lengths of LCFAs, whereas DES consisting of lauric acid (LA) exhibited the highest enhancing effect. FTIR, DSC, and molecular docking further demonstrated consistency between micro molecular mechanism and macro penetration behavior. Additionally, HaCaT cells treated with DESs showed high cell viability, suggesting their good skin safety. Taken together, OMT-LCFA DESs would be a promising penetration enhancer for transdermal drug delivery, which also provides guidance for the design of new DESs.

In situ formation of deep eutectic solvents based dispersive liquid–liquid microextraction for the enrichment of trace phthalate esters in aqueous samples

In this work, several new in situ deep eutectic solvents (DESs) were prepared with two low toxic phenols thymol and p-cresol as hydrogen bond donors (HBDs) and three biodegradable esters 3-hydroxyhexanoate, butyl lactate and methyl salicylate as hydrogen bond acceptors (HBAs), and the in situ formation of DESs could be achieved at room temperature. Based on the in situ formation of DESs, a dispersive liquid–liquid microextraction (DLLME) method was developed to enrich four phthalate esters (PAEs) from water and beverage samples combined with gas chromatography-flame ionization detection (GC-FID). After the most appropriate type of DES was determined, the influencing factors of the in situ DES-based DLLME procedure were explored and optimized by Design of experiment (DoE). The optimized in situ DES-based DLLME approach exhibited good linearity in the range of 1–800 µg/L with determination coefficient (R2) from 0.9936 to 0.9983, limits of detection (LODs) within 0.5–2 μg/L, enrichment factors (EFs) from 256.3 to 467.1 and extraction recoveries (ERs) of 51.26 %-93.42 %. Finally, the proposed method was successfully applied for the determination of PAEs in water and beverage samples contacted with plastics, and good practical applicability was presented with the spiked recoveries of 76.17 %-118.09 %.

(Physical and Analytical Electrochemistry Division Max Bredig Award In Molten Salt and Ionic Liquid Chemistry) Of Ionic Liquids and Hydrogen Bonds

Whether it is the solubility of biopolymers, the rates of reactions, the physical properties of ionic liquids, or the formation of Deep Eutectic Solvents, the concept of the hydrogen bond often finds itself at the centre of explanations of ionic liquids’ behaviours. How strange it would seem to someone entering the field today that the idea that hydrogen bonds could form in ionic liquids was even recently controversial. So, how did this transformation come about?In this presentation, you will meet some of the most well-known names in ionic liquids, both past and present. Key insights have only come from a variety of different techniques, both experimental and theoretical, being brought to bear on the question of whether hydrogen bonds exist or are of any use in ionic liquids and their solutions. You will also see that opposing views can turn out to both be correct and controversies are not always solved by one side ‘winning’ over the other.

Stir membrane liquid-phase microextraction based on milk fats hydrolysis and deep eutectic solvent formation: Determination of bisphenols

In this paper, a stir membrane liquid-phase microextraction approach based on milk fats hydrolysis and in situ deep eutectic solvent formation was developed for the first time. The approach was applied to clean-up and preconcentrate bisphenols from milk samples. The procedure assumed alkaline hydrolysis of samples fats to obtain water-soluble salts of fatty acids that acted as precursors for the deep eutectic solvent formation. A stir membrane disk impregnated with menthol was placed into the sample solution. The formation of microdroplets of the hydrophobic fatty acids was observed under sample acidification. Collection of the extract phase on the disk was based on deep eutectic solvent formation. Under optimal conditions, the RSD was < 6 %, limits of detection for bisphenols were 0.3–0.5 μg kg−1. The extraction recoveries were in the range of 95–97 %, which indicated the excellent capability of the developed approach to extract hydrophobic analytes from complex matrices.

Stepping away from serendipity in Deep Eutectic Solvent formation: Prediction from precursors ratio

Deep Eutectic Solvents (DESs) are a class of environment friendly and cheap solvents that are effectively employed in many different fields; nevertheless, a thorough elucidation of their structure is still lacking and the unambiguous categorization of a mixture as a DES is challenging. Throughout this paper, we develop a procedure based on computational tools (supported by experimental data) that could help in making a priori predictions of DESs formation. After validating the approach with X-ray scattering data, a series of aromatic molecules (as Hydrogen Bond Donor, HBD) was investigated to corroborate the method that could be potentially extended to other DESs. The computational findings evidenced a remarkable and unprecedented predictive power. Furthermore, as a bridge between computed and experimental data, a linear correlation between the calculated chloride-HBD coordination number and the decrease of the freezing temperature of the mixtures is found, being 0.7 a threshold value to obtain a liquid eutectic mixture at room temperature as further validated by experimental Raman spectra. This approach has been preliminary tested also with DESs based on alternative HBDs (i.e., aliphatic alcohols, amines, and carboxylic acids), confirming the flexibility and the generality of the method.

Fast and energy-effective deep eutectic solvent-based microextraction approach for the ICP-OES determination of catalysts in biodiesel

In this research a reversed-phase deep eutectic solvent-based air-assisted dispersive liquid-liquid microextraction approach was presented for the first time and applied to the determination of catalysts (sodium, potassium, calcium and magnesium) in biodiesel samples by the inductively coupled plasma-optical emission spectroscopy. Catalysts in samples were extracted with the hydrophilic deep eutectic solvent with the assistance of air. The obtained extract phase after phase separation was analyzed by the spectral method. In this procedure the natural three-component deep eutectic solvent based on choline chloride, lactic acid and water provided fast (15 instant extraction cycles) and effective mass-transfer (extraction recovery 95-98 %). Lactic acid as precursor of the deep eutectic solvent in the presence of water provided an effective condition for separation of doubly charged metal ions. Choline chloride acted as water-soluble hydrogen bond acceptor for the deep eutectic solvent formation. The developed procedure was utilized for analysis of different nature biodiesel samples and certified reference material. It was evaluated, that the procedure is sensitive (limits of detection 3 µg kg−1), well reproducible (RSD < 7%), green (no hazardous organic solvents and mineral acids) and energy-effective (no microwave digestion of samples).

An effervescence-assisted dispersive liquid-liquid microextraction based on three-component deep eutectic solvent for the determination of fluoroquinolones in foods

An effervescence-assisted dispersive liquid-liquid microextraction approach using three-component deep eutectic solvent based on short-chain and medium-chain carboxylic acids and terpenoid was developed for the first time. The microextraction procedure was applied to the determination of fluoroquinolone antibiotics in foods (milk and shrimp samples) by high-performance liquid chromatography with fluorometric detection. In this microextraction procedure three-component deep eutectic solvent acted as a proton donor agent and an extractant. The carbon dioxide bubbles caused by the fast reaction between precursor of deep eutectic solvent (short-chain carboxylic acid) and effervescent agent (sodium carbonate) promoted the dispersion of the extractant in an aqueous sample phase. Various carboxylic acids were studied as hydrogen bond donors for the formation of deep eutectic solvents and proton donor agents for the generation of CO2 bubbles. Two natural terpenoids (menthol and thymol) were studied as the hydrogen bond acceptors for the formation of three-component solvent. The extraction system based on heptanoic acid and thymol (1:2, mol/mol) containing formic acid (proton donor for generating CO2 bubbles) provided maximum extraction recovery (86–99%) and a higher extraction efficiency of analytes compared to their extraction into individual hydrophobic precursors of the system. The LODs, calculated from the blank tests based on 3σ, were varied from 0.03 to 0.06 μg L−1 and from 0.3 to 0.6 μg kg−1 for fluoroquinolone antibiotics in milk and shrimp samples, respectively. The proposed approach provided effective dispersion of extractant speeding up the extraction process and fast separation of phases without any external energy assistance.

Liquefying Flavonoids with Terpenoids through Deep Eutectic Solvent Formation.

The formation of deep eutectic solvents (DES) is tied to negative deviations to ideality caused by the establishment of stronger interactions in the mixture than in the pure DES precursors. This work tested thymol and menthol as hydrogen bond donors when combined with different flavonoids. Negative deviations from ideality were observed upon mixing thymol with either flavone or flavanone, two parent flavonoids that only have hydrogen bond acceptor (HBA) groups, thus forming non-ionic DES (Type V). On the other hand, the menthol systems with the same compounds generally showed positive deviations from ideality. That was also the case with the mixtures containing the more complex hydroxylated flavonoid, hesperetin, which resulted in positive deviations when mixed with either thymol or menthol. COSMO-RS successfully predicted the behavior of the solid-liquid phase diagram of the studied systems, allowing for evaluation of the impact of the different contributions to the intermolecular interactions, and proving to be a good tool for the design of DES.

Water based-deep eutectic solvent for ultrasound-assisted liquid–liquid microextraction of parabens in edible oil

A novel water-based deep eutectic solvent was synthesized and used for the ultrasound-assisted liquid–liquid microextraction of parabens in edible oil and for their determination by high performance liquid chromatography. Herein, the water-based deep eutectic solvent was formulated at room temperature by tetrabutylammonium chloride as hydrogen bond acceptor and water as hydrogen bond donor at the molar ratio of 1:5. As component, water has the effect on tailoring the physicochemical properties of water-based deep eutectic solvent and assisting tetrabutylammonium chloride (hydrogen bond acceptor) capturing parabens (hydrogen bond donor) through in-situ deep eutectic solvent formation. The developed method has satisfactory linearity (1.5–500 μg/L), limits of detections (0.2–0.4 μg/L), precisions (RSDs ≤ 5.8%), and was fruitfully applied to detect parabens in edible oil with excellent recoveries (85.1–106.8%). The feature of the procedure lies in simplicity, low cost and high sensitivity, and this can be extended for the efficient separation of other hydrophobic compounds.

Molecular mechanism and extraction performance evaluation of diethylene glycol-based DES for extraction desulfurization process of fuel oil

From July 1, 2020, China has fully implemented the most stringent National VI emission standards for automobiles. Thiophenes (TPs) are main form of sulfur compounds in China crude oil. More than 80% of TPs is composed of dibenzothiophene (DBT). The upgrade of emission regulations will drive technological upgrades. Deep eutectic solvent (DESs) has great potential for industrial application because of its simple preparation, low cost and high extraction rate. Based on the quantum chemistry (QC), this work proposed a screening method for DESs to extract DBT from Heptane + DBT mixtures. Through quantum chemical (QC) calculation, the probability distribution of surface charge density σ (σ-profile) was obtained, and suitable DES was selected as the extractant. Molecular dynamics (MD) simulation of the microscopic behavior of the involved DESs and mixtures was carried out, and the diffusion and aggregation behavior of sulfides in DES were studied. Through the analysis of intermolecular interaction energy, radial distribution function, spatial distribution function and self-diffusion coefficient, the formation of DESs and the extraction mechanism of DBT as well as the influence of hydrogen bond acceptors (HBA)/ hydrogen bond donors (HBD) type and molar ratio were explained. The effects of process parameters and thiophene compounds on desulfurization were studied.