Types Of Deep Eutectic Solvents Research Articles

Starch treatment with deep eutectic solvents, ionic liquids and glycerol. A comparative study

In this work changes in potato starch during processing (dissolution and plasticization via thermocompression) in the presence of three types of media: deep eutectic solvents (DES) with different anions in choline salts and components molar ratios, ionic liquids (IL) and glycerol (G) were investigated. Urea-based DES and IL exhibited dissolving capacity towards starch (confirmed with microscopic observations and DSC). Plasticizing ability was studied using rheological characteristics of starch/media premixtures as well as mechanical tests, DMA, XRD and FTIR analysis of thermoplastic starch (TPS). Additionally, influence of concentration of two types of DES: dissolving and non-dissolving on final properties was investigated. Results revealed that viscosity of premixtures with DES and IL was lower that with G. Dissolving DES and IL led to highly amorphous materials with lower tensile strength and much higher elongation at break than TPS with non-dissolving DES and G. Imidazolium IL significantly decreased thermal stability of TPS.

Basic deep eutectic solvents as reactant, template and solvents for ultra-fast preparation of transition metal oxide nanomaterials

Developing a new type of deep eutectic solvents (DESs) is indispensable for expanding their application in various fields. Here, we report a series of new highly basic DESs. FT-IR, quantitative 1H NMR, MD simulation and physical properties show that these basic liquids are made up of hydroxide acceptor of alkali metal hydroxides in which the hydrogen bonding interactions coordinate the donor. These DESs can be played three roles as new solvents, template and reactant for facile and ultra-fast preparation of transition metal oxide nanomaterials such as NiCo2O4, MnCo2O4, NiMn2O4, CoCu2O4 and Co3O4 under mild condition. This work shows one of the low energy-intensive methods for nanomaterial preparation. These initial findings of basic deep eutectic solvents provide a potential applicability around the systematic development of transition metal oxide nanosheets.

Hydrated-Metal-Halide-Based Deep-Eutectic-Solvent-Mediated NiFe Layered Double Hydroxide: An Excellent Electrocatalyst for Urea Electrolysis and Water Splitting.

The liquid structures of deep eutectic solvents (DESs) based on hydrated metal halides and their application as electrolytes have been widely studied. However, little attention has been paid to the direct use of this type of DES in the preparation of micro-/nanomaterials. Herein, an FeCl3 ⋅6 H2 O/urea DES was used in the one-step synthesis of NiFe-LDH_D with a nanoflower morphology. In alkaline media, this catalyst promoted excellent electrocatalytic activity for the oxidation of urea at potential of 1.32 V (vs. RHE) and for the oxygen-evolution reaction at a potential of 1.39 V to achieve a current density of 10 mA cm-2 . These results were superior to the results with NiFe-LDH/NF that was obtained from an aqueous solution of FeCl3 , as well as most of the previously reported transition-metal catalysts. Furthermore, NiFe-LDH_D/NF could be readily implemented as both a cathode and an anode for the electrolysis of urea and water splitting. The use of hydrated-metal-halide-based DESs for the preparation of LDH catalysts through a dipping-redox strategy should both enrich the research of DESs and offer guidance for the rational surface engineering of catalysts for the electrolysis of urea and overall water splitting with high performance.

Preconcentration and Determination of Chlorophenols in Wastewater with Dispersive Liquid–Liquid Microextraction Using Hydrophobic Deep Eutectic Solvents

Hydrophobic deep eutectic solvents (DESs) were synthesized and developed for the preconcentration of three chlorophenols from wastewater by dispersive liquid–liquid microextraction (DLLME). The analyte concentrations were determined by high-performance liquid chromatography (HPLC). The hydrophobic DESs were prepared with the combination of hydrogen bond donors of decanoic acid or octanoic acid with different hydrogen bond acceptors of quaternary ammonium salts of tetrabutylammonium chloride, tetraoctylammonium chloride, methyltrioctylammonium chloride, and tetraheptylammonium chloride). Following the study of the stability and characterization by Fourier transform infrared spectroscopy, the hydrophobic DESs were developed as extractants and employed for the removal of 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) from wastewater. Using hydrophobic DESs as the microextraction solvents, several key parameters were optimized, including the type and volume of the hydrophobic DES, pH, and time of the extraction procedure. Under the optimized conditions, good recoveries from 90.8% to 93.0% were obtained for the three chlorophenols. The limits of detection were less than 0.05 µg/mL with relative standard deviations between 1.8% and 3.1%. The method was applied for the isolation and determination of synthetic chlorophenols in wastewater.

Green approaches for the extraction of antioxidants from eucalyptus leaves

Leaf extracts of Eucalyptus globulus present a wide range of phenolic compounds with interest in the pharmaceutical, health, agricultural, cosmetic and food industries because of their medicinal properties. Although conventional solvent extraction is the most extensively used methodology to extract and isolate these active compounds, the excessive consumption of time and energy makes its application relatively inefficient. This study investigates other more cost-effective and environmentally friendly techniques for the isolation of antioxidant phenolic compounds, such as enzyme assisted extraction (EAE), microwave assisted extraction (MAE), ultrasound assisted extraction (UAE), and deep eutectic solvent (DES) extraction. First, the conventional extraction was used to evaluate the effect of the particle size and the liquid-to-solid ratio. Next, relevant parameters of the green extraction techniques were optimized, such as time of extraction, enzyme and dose used, microwave power, and type of DES. The optimized extracts from MAE, UAE, DES and conventional extraction were characterized by UHPLC-ESI-MS, showing a similar phenolic profile with 26 tentatively identified compounds. Finally, the conditions leading to the extracts with the highest content in phenolics were evaluated in terms of specific energy consumption. The lowest specific energy consumption was obtained with MAE, with a value more than 13 times lower than conventional extraction.

Miniaturized matrix solid-phase dispersion based on deep eutectic solvent and carbon nitride associated with high-performance liquid chromatography: A new feasibility for extraction and determination of trace nitrotoluene pollutants in soil samples

In this research, a miniaturized version of matrix solid phase dispersion (MSPD) method was developed for successful extraction of five nitrotoluenes from soil samples. The terpene based deep eutectic solvent (DES) composed of borneol and DL-menthol was used simultaneously as extraction solvent and dispersing liquid. Graphitic-carbon nitride (g-C3N4) as sorbent was prepared by pyrolysis of melamine at a muffle furnace. The MSPD mixture was obtained by grinding soil, DES, and g-C3N4. Minimum amount of acetonitrile was used in the elution step. Some experimental variables including type and volume of DES, type of dispersant, mass ratio of dispersant to sample, volume of elution solvent, grinding time, and ultrasonication time were evaluated. Analysis of extracted samples was performed by high performance liquid chromatography-ultra violet detection. Under the optimized conditions; the limits of detection were achieved in the range of 0.12−0.33 μg g−1, and the relative standard deviations were equal to or lower than 9.3%. The extraction recoveries were ranged from 78 to 96%. This straightforward and fast method is effective for environmentally friendly extraction of nitrotoluenes from soil samples.

Comparison of deep eutectic solvents (DES) on pretreatment of oil palm empty fruit bunch (OPEFB): Cellulose digestibility, structural and morphology changes

In this work, a novel solvent, deep eutectic solvent (DES) was applied to examine its effectiveness in pretreating OPEFB. Three types of DESs, i.e. choline chloride-lactic acid (ChCl-LA), choline chloride-urea (ChCl-U) and choline chloride-glycerol (ChCl-G) were investigated. The pretreatment performance was based on cellulose digestibility, structural and morphology changes. At molar ratio of 1:2, ChCl-LA attained the highest reducing sugars yield of 20.7%, followed by ChCl-G (20.0%) and ChCl-U (16.9%). FT-IR and SEM results further confirmed the outstanding ability of ChCl-LA due of its ability in cellulose, hemicellulose and lignin disruption, exposing its cellulose fraction to enzymatic hydrolysis. ChCl-LA is also more favorable compare to acid and alkaline solvents as it could prevent sugars loss, use of expensive corrosion resistant equipment and ease products separation.

Kinetic study on the reaction of lauric acid with ethanol catalyzed by deep eutectic solvent based on cetyl trimethyl ammonium bromide

AbstractIn this work, a novel type of deep eutectic solvents (DES: CTAB–DES) based on cetyl trimethyl ammonium bromide (CTAB) was successfully synthesized by mixing CTAB with p‐toluenesulfonic acid monohydrate and applied as catalysts for the esterification reaction of ethanol and lauric acid. The kinetics of the reaction of ethanol and lauric acid catalyzed by CTAB–DES was investigated in the temperature range of 328.15–348.15 K. The influence of different parameters including agitation speed, temperature, catalyst loading, and the lauric acid to ethanol molar ratio on the conversion of lauric acid was discussed. The kinetic experimental data obtained were correlated by the pseudo‐homogeneous model, and the results show that it can predict the reaction process well. Moreover, CTAB–DES can be reused six times without any significant decrease in catalytic activity.

Comparison of hydrophilic and hydrophobic deep eutectic solvents for pretreatment determination of sulfonamides from aqueous environments

Two types of deep eutectic solvents were synthesized for an aqueous two-phase system to determine the sulfonamides from environmental water samples. The ChCl-Ph based ATPS showed good extraction efficiency. The method avoids use of a large number of extraction solvents.

Kinetics of the reaction of ethanol and lauric acid catalyzed by deep eutectic solvent based on benzyltrimethylammonium chloride

AbstractIn this work, three types of deep eutectic solvents (DESs: BAC‐PTSA, BAC‐2PTSA, and BAC‐3PTSA) based on benzyltrimethylammonium chloride (BAC) were successfully synthesized by mixing benzyltrimethylammonium chloride with p‐toluenesulphonic acid monohydrate (PTSA) and used as catalysts for the esterification reaction of ethanol and lauric acid. The kinetics of the reaction of ethanol and lauric acid in the presence of DESs as catalysts was investigated systemically in the temperature range of 333.15–353.15 K. The influences of different parameters including type of DESs, reaction temperature, catalyst loading, and initial reactant molar ratio on the conversion of lauric acid were discussed. The kinetic experimental data obtained were successfully correlated by the pseudohomogeneous (PH) model based on the activities. Moreover, BAC‐3PTSA is easily synthesized and reused six times without any significant decrease in catalytic activity.

Developing a new and simple ultrasound-assisted emulsification liquid phase microextraction method built upon deep eutectic solvents for Patent Blue V in syrup and water samples

In this study, Deep Eutectic Solvents (DESs) were utilized for ultrasound-assisted emulsification liquid phase microextraction (UA-ELPME) of Patent Blue V in syrup and water samples. Patent Blue V in sample solution of pH 4.0 was extracted into DES phase prepared from choline chloride and phenol. Concentration of Patent Blue V in final DES phase was measured at 627.5 nm with Uv-Vis spectrophotometry. Sample volume, pH, matrix effect, volume and type of DES, ultrasonication and centrifugation times were investigated and optimized. The developed UA-ELPME method presents a limit of detection (LOD) of 0.37 μg L−1, preconcentration factor of 15 and a relative standard deviation (RSD, %) of 6.0% under the optimum conditions. The validation was carried out with standard addition-recovery experiments for syrup and water samples. The obtained recovery results showed that the developed UA-ELPME method was applicable for routine Patent Blue V analysis in syrup and water samples.

Extraction of flavonoids in Prunella vulgaris based on deep eutectic solvent method：application of new green solvent

Flavonoids have attracted much attention due to their good anti-inflammatory, anti-oxidation and anti-tumor effects. At present, the extraction of flavonoids is mainly based on organic solvent, while the researches on the use of green and safe solvents are quite limited. Therefore, in the present study, different types of deep eutectic solvents (DESs) were applied to investigate their effect on extraction of flavonoids and optimize the process, also investigate the recovery efficiency of DESs and evaluate the recovery method for total flavonoids. The extraction yield of the total flavonoids acted as the comprehensive evaluation indexes, and a central composite design (CCD) of response surface methodology (RSM) was employed to further optimize the alcohol-based DES extraction conditions. The results showed that the optimized extraction conditions were as follows: water-DES ratio of 27%, solid-liquid ratio of 15 mL·g⁻¹, extraction temperature of 83 °C and extraction time of 42 min in ChCl-glycerol at 1:4 ratio. Under these conditions, the mean experimental value of the extraction yield (75.05 mg·g⁻¹) corresponded well with the predicted value (77.86 mg·g⁻¹). Moreover, these experimental results showed more advantages such as in higher efficiency, economy and environmental protection as compared with previously reported conventional extraction methods. In addition，the recovery yield of the total flavonoids from the DESs extraction solution achieved 97.88% by using AB-8 macroporous resin, and 88.12% desorption ratio can be achieved by 100% ethanol with 5 times resin content. After the above treated DESs were collected, the extraction yield with the same method reached 95.23%, indicating that the method of macroporous resin can be used for efficient and simple recovery and reuse. This study suggests that DESs can be used as a kind of sustainable and efficient natural extraction solvents for extraction of flavonoids from Prunella vulgaris.

Extended hierarchical solvent perturbations from curved surfaces of mesoporous silica particles in a deep eutectic solvent

HypothesisMany applications of deep eutectic solvents (DES) rely on exploitation of their unique yet complex liquid structures. Due to the ionic nature of the DES components, their diffuse structures are perturbed in the presence of a charged surface. We hypothesize that it is possible to perturb the bulk DES structure far (>100 nm) from a curved, charged surface with mesoscopic dimensions. ExperimentsWe performed in situ, synchrotron-based ultra-small angle X-ray scattering (USAXS) experiments to study the solvent distribution near the surface of charged mesoporous silica particles (MPS) (≈0.5 µm in diameter) suspended in both water and a common type of DES (1:2 choline Cl-:ethylene glycol). FindingsA careful USAXS analysis reveals that the perturbation of electron density distribution within the DES extends ≈1 μm beyond the particle surface, and that this perturbation can be manipulated by the addition of salt ions (AgCl). The concentration of the pore-filling fluid is greatly reduced in the DES. Notably, we extracted the real-space structures of these fluctuations from the USAXS data using a simulated annealing approach that does not require a priori knowledge about the scattering form factor, and can be generalized to a wide range of complex small-angle scattering problems.

Magnetic molecularly imprinted polymers based on silica modified by deep eutectic solvents for the rapid simultaneous magnetic-based solid-phase extraction of Salvia miltiorrhiza bunge, Glycine max (Linn.) Merr and green tea.

Novel magnetic molecularly imprinted polymers (MMIPs) with multiple-template based on silica were modified by four types of deep eutectic solvents (DESs) for the rapid simultaneous magnetic solid-phase extraction (MSPE) of tanshinone Ⅰ, tanshinone ⅡA, and cryptotanshinone from Salvia miltiorrhiza bunge; glycitein, genistein, and daidzein from Glycine max (Linn.) Merr; and epicatechin, epigallocatechin gallate, and epicatechin gallate from green tea, respectively. The synthesized materials were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Single factor experiments were to explore the relationship between the extraction efficiency and four factors (the sample solution pH, amount of DESs for modification, amount of adsorbent, and extraction time). It was showed that the DES4-MMIPs have better extraction ability than the MMIPs without DESs and the other three DESs-modified MMIPs. The best extraction recoveries with DES4-MMIP were tanshinone Ⅰ (85.57%), tanshinone ⅡA (80.58%), cryptotanshinone (92.12%), glycitein (81.65%), genistein (87.72%), daidzein (92.24%), epicatechin (86.43%), epigallocatechin gallate (80.92%), and epicatechin gallate (93.64%), respectively. The novel multiple-template MMIPs materials modified by DES for the rapid simultaneous MSPE of active compounds were proved to reduce the experimental steps than single-template technique, and increase the extraction efficiency.

Hollow fibre-supported graphene oxide nanosheets modified with a deep eutectic solvent to be used for the solid-phase microextraction of silver ions

ABSTRACTA deep eutectic solvent (DES) of choline chloride and thiourea was synthesised, immobilised on the surface of graphene oxide (GO) nanosheets and reinforced inside the pores of the hollow fibre (DES-GO-HF). Then, solid-phase microextraction flame atomic absorption spectrometry was designed for separation, preconcentration and determination of trace amounts of silver. Various parameters affecting the extraction recovery of the analyte, such as pH, sample volume, type of DES, extraction time, length of the hollow fiber, nature, as well as the volume and concentration of the eluent, were investigated and optimised. Under optimum conditions, the method showed good linearity in the concentration range of 1.0–40.0 µg L−1 with the determination coefficient of (r2) 0.9990 for silver. The method was very sensitive and has limits of detection and quantification (defined as 3Sb/m and 10Sb/m) of 0.2 and 0.7 µg L−1, respectively. The method was successfully applied for the determination of Ag(I) in water, wastewater, ore and hair samples. The accuracy of the method was evaluated through the recovery experiments and the analysis of certified reference materials.

Assessment of Natural Deep Eutectic Solvent Pretreatment on Sugar Production from Lignocellulosic Biomass

Before the conversion of lignocellulosic biomass into fuel such as ethanol, the biomass needs to be pretreated and the yield of ethanol is highly dependent on the pretreatment efficiency. This study investigate the performance of deep eutectic solvent (DES) in pretreating sago waste which is a type of starchy biomass. The suitable type of DES in sago waste pretreatment was selected based on three criteria, which is the structural characteristic, the sugar yield during enzymatic hydrolysis and the amount of sugar loss during pretreatment. In this study, three types of DES namely Choline Chloride-Urea (ChCl-Urea), Choline Chloride-Citric acid (ChCl-CA) and Choline Chloride-Glycerol (ChCl-Glycerol) was investigated. The effect of temperature and duration on DES pretreatment was also investigated. All DES reagents were able to disrupt the structure and increase the porosity of sago waste during pretreatment. ChCl-Urea was selected in this study as it shows apparent structural disruption as examined under Scanning Electron Microscope (SEM). The highest glucose yield of 5.2 mg/mL was derived from enzymatic hydrolysis of ChCl-Urea pretreated sago waste. Moreover, reducing sugar loss during ChCl-Urea pretreatment was low, with only 0.8 mg/mL recorded. The most suitable temperature and duration for ChCl-Urea pretreatment is at 110°C and 3 hr. In a nutshell, the application of DES in pretreatment is feasible and other aspects such as the biodegradability and recyclability of DES is worth investigating to improve the economic feasibility of this pretreatment technique.

Magnetic molecularly imprinted polymers for recognition and enrichment of polysaccharides from seaweed.

New magnetic molecularly imprinted polymers with two templates were fabricated for the recognition of polysaccharides (fucoidan and alginic acid) from seaweed by magnetic solid-phase extraction, and the materials were modified by seven types of deep eutectic solvents. It was found that the deep eutectic solvents magnetic molecularly imprinted polymers showed stronger recognition and higher recoveries for fucoidan and alginic acid than magnetic molecularly imprinted polymers, and the deep eutectic solvents-4-magnetic molecularly imprinted polymers had the best effects. The practical recovery of the two polysaccharides (fucoidan and alginic acid) purified with deep eutectic solvents-4-magnetic molecular imprinted polymers in seaweed under the optimal conditions were 89.87, and 92.0%, respectively, and the actual amounts extracted were 20.6 and 18.7μg/g, respectively. To sum up, the developed method proved to be a novel and promising method for the recognition of complex polysaccharide samples from seaweed.

The friction theory for modeling the viscosities of deep eutectic solvents using the CPA and PC-SAFT equations of state

Deep Eutectic Solvents (DESs), as recently introduced green solvents, are interesting for different fields and applications. Most of the known DESs have high viscosities, which change dramatically with temperature. Therefore, the viscosity of a DES is most often one of the vital physical properties which must be known accurately. Because of the strong non-ideal interactions between the constituents, as well as the dramatic changes of DES viscosity with temperature, modeling and predicting the viscosities of DESs over wide ranges of temperatures is very challenging. In this study, a viscosity approach is used and implemented into two advanced association equations of state for different families of deep eutectic solvents. The cubic plus association (CPA) and the perturbed chain-statistical associating fluid theory (PC-SAFT) equations of state (EoSs), which are two powerful models to handle associating compounds, have been coupled with the friction theory, which is itself among the successful theoretical viscosity models of literature. Twenty-seven different types of DESs, for which density and viscosity data are available in open literature, were considered. A large density databank, consisting of 590 density data over wide ranges of temperatures and pressures, together with a large viscosity databank covering 253 viscosity data over wide ranges of temperatures at atmospheric pressure were collected. The resulting friction theory models with the CPA and PC-SAFT EoSs were checked against experimental data and their deviations were found to be the same and equal to 4.4%. Such accuracy showed the promising capability of both models. By changing the hydrogen bond donor types for a fixed hydrogen bond acceptor, the accuracies of the models were also shown to be good with respect to experimental values. In addition, both models perfectly followed the trends of changing ratios of hydrogen bond donors to hydrogen bond acceptors. The viscosity-temperature trend of the different DESs was also successfully modeled.

Optimization of the chromatographic behaviors of quercetin using choline chloride-based deep eutectic solvents as HPLC mobile-phase additives

ABSTRACTNine types of deep eutectic solvents (DESs) were used as mobile-phase additives to improve the chromatographic behaviors of quercetin. Three variables (temperature, molar ratio and concentration) were studied. According to the ion interaction theory and the hydrogen bond, DESs components can work as ions and play an ion-pairing role with quercetin at the same time. Under the optimum condition, the number of theoretical plates was 6690.8 and the tailing factor was 1.71. Compared with acetic acid (HAc), DESs as mobile-phase additives would not damage the High Performance Liquid Chromatography (HPLC) system. The excellent properties of DESs showed their potential as additives for the determination of quercetin.

Liquid–liquid microextraction of synthetic pigments in beverages using a hydrophobic deep eutectic solvent

A method was developed for the determination of eight synthetic pigments in beverage samples by liquid–liquid microextraction followed by high performance liquid chromatography. Using hydrophobic deep eutectic solvent (DES) as the microextraction solvent, several key parameters were optimized, including the type and volume of the hydrophobic DES, pH value, vortex time and salt content. Detection limits were in the range 0.016–1.12 ng/mL, recoveries were in the range 74.5–102.5% and relative standard deviations were <5.4%. The method is simple, green and practical, and could be applied to the extraction and determination of synthetic pigments in beverages.