Kinds Of Deep Eutectic Solvents Research Articles

Microwave-assisted DES fabrication of lignin-containing cellulose nanofibrils and its derived composite conductive hydrogel

Deep eutectic solvents (DES) have been regarded as green solvents in the biorefinery of lignocellulosic biomass, but long duration time has severely limited efficiency. The microwave-assisted DES pretreatment along with enzymatic hydrolysis and high-pressure homogenization process was proposed to produce lignin-containing cellulose nanofibrils (LCNF) from corncob. Benefiting from microwave-assisted DES pretreatment, the duration time was greatly shortened; meanwhile the effects of different kinds of DES on the resultant LCNF were investigated. The results showed that, the microwave-assisted DES fabricated LCNF (M-LCNF) was successfully obtained, exhibiting good nano size, thermal stability, colloidal stability, and fluorescence. M-LCNF was further introduced into phytic acid (PA) enhanced poly(acrylamide-co-acrylic acid) (P(AM-co-AA)) network and constructed composite conductive hydrogels (PLP). The obtained hydrogels exhibited good mechanical strength, UV blocking ability, fluorescence, and conductivity. A simple battery assembled with the resultant PLP as electrolyte had an out voltage of 2.41 V. The composite conductive hydrogel showed good sensing performance towards different stimuli (e.g., stretching and compression) and human motions in real time. It is expected that this research would provide an alternative way for green fabrication of LCNF and potential application of LCNF in flexible sensors.

Ultrasonic-assisted extraction of flavonoids from peanut leave and stem using deep eutectic solvents and its molecular mechanism

Natural bioactive compounds extracted from agricultural by-products have received considerable attentions. Twenty-two kinds of deep eutectic solvents (DESs) with ultrasonic were screened to extract flavonoids from peanut leave and stem. ChCl-acetic acid (ChCl-Aa) with 1:2 M ratio resulted in more effective extraction of flavonoids compared to other solvents The best extraction conditions were found to be at a 27% water content in DES/H2O, for 43 min with 31:1 g/mL liquid/solid ratio, giving 2.980 mg/g dw of flavonoids through the response surface method. SEM showed that ChCl-Aa had a certain dissociation impact on the sample matrix, while 1H NMR analysis revealed the formation of hydrogen bonds between daidzein and ChCl-Aa. Changes in the H–bond length and number were observed by the B3LYP/6-31G (d,p) level of theory to confirm the experimental spectra. This study reveals that DESs are efficient for obtaining value-added products and could applied to other natural products.

Synthesis of isoamyl hexanoate catalyzed by deep eutectic solvent based on benzyltrimethylammonium chloride: RSM and ANN optimization and kinetics

AbstractBackgroundIsoamyl hexanoate is a widely used edible spice. In this paper, the process and kinetics of the esterification of hexanoic acid and isoamyl alcohol to isoamyl hexanoate catalyzed by deep eutectic solvents (DESs) were studied. Several kinds of DESs (BTMAC‐zPTSA) were prepared from benzyltrimethylammonium chloride (BTMAC) and p‐toluenesulfonic acid monohydrate (PTSA) with a molar ratio of z. The synthesis process of isoamyl hexanoate was optimized by response surface methodology and artificial neural network. The effects of process conditions such as the kind and load of catalyst, alcohol/acid ratio and reaction temperature were studied. In the temperature range of 338.15 to 368.15 K, BTMAC‐1.2PTSA was selected as the catalyst, and then the kinetic data and chemical equilibrium composition of the esterification of hexanoic acid with isoamyl alcohol were determined.ResultsAfter optimizing the synthesis process of isoamyl hexanoate using response surface methodology and artificial neural network, the conversion rate of hexanoic acid increased to 92.15%. The esterification reaction kinetics were described using a pseudo‐homogeneous model based on activity, with an average relative deviation of 1.9% and activation energy of 25.79 kJ mol−1. The catalytic performance of catalyst BTMAC‐1.2PTSA remains good after five cycles of use.ConclusionThe established kinetic model has a good predictive effect on the kinetic data for the synthesis of isoamyl hexanoate. The catalyst BTMAC‐1.2PTSA has good stability and recyclability, and has the potential to replace traditional catalysts in the production of isoamyl hexanoate. © 2023 Society of Chemical Industry.

Physicochemical Properties, Thermal Stability, and Pyrolysis Behavior of Antioxidative Lignin from Water Chestnut Shell Obtained with Ternary Deep Eutectic Solvents.

The molecular weight of lignin extracted from lignocellulosic biomass is an important factor in determining its valorization in industrial processes. Herein, this work aims to explore the extraction of high molecular weight and bioactive lignin from water chestnut shells under mild conditions. Five kinds of deep eutectic solvents were prepared and applied to isolate lignin from water chestnut shells. The extracted lignin was further characterized with element analysis, gel permeation chromatography, and Ultraviolet-visible and Fourier-transform infrared spectroscopy. The distribution of pyrolysis products was identified and quantified with thermogravimetric analysis-Fourier-transform infrared spectroscopy and pyrolysis-gas chromatograph-mass spectrometry. The results showed that choline chloride/ethylene glycol/p-toluenesulfonic acid (1:1.8:0.2 molar ratio) exhibited the highest fractionation efficiency for lignin (84.17% yield) at 100 °C for 2 h. Simultaneously, the lignin showed high purity (90.4%), high relative molecular weight (37,077 g/mol), and excellent uniformity. Furthermore, the aromatic ring structure of lignin remained intact, consisting mainly of p-hydroxyphenyl, syringl, and guaiacyl subunits. The lignin generated a large number of volatile organic compounds during the depolymerization process, mainly composed of ketones, phenols, syringols, guaiacols, esters, and aromatic compounds. Finally, the antioxidant activity of the lignin sample was evaluated with the 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay; the lignin from water chestnut shells showed excellent antioxidant activity. These findings confirm that lignin from water chestnut shells has a broad application prospect in valuable chemicals, biofuels and bio-functional materials.

Liquid-liquid extraction and mechanism analysis of extracting fuel additive isopropanol from mixture with choline-based deep eutectic solvents as efficient extractants

• Choline-based DESs was prepared for the separation of IPA- n -heptane. • The extraction performance of three kinds of DESs was compared by LLE experiment. • MD simulation was used to explore the mechanism of extraction process. • The effect of azeotrope ratio on extraction was studied. Deep eutectic solvents (DESs) have wide application prospects in azeotropic separation since of their advantages of good thermal stability, non harmfulness and low raw material price. As a green solvent, DESs has attracted more and more attention in recent years. As a high-quality fuel additive, isopropanol (IPA) has high chemical added value because of its high energy density, low volatile and small corrosive. Therefore, extracting high alcohols such as IPA from azeotropes can effectively improve the combustion efficiency of fossil fuels and reduce tail gas emissions. In this work, ethylene glycol and other hydrogen bond receptors were selected to synthesize three choline-based DESs to extract IPA from n -heptane. The selectivity of DESs to IPA was obtained by liquid–liquid equilibrium (LLE) experiment and the separate efficiency of diverse DESs was compared. To profoundly investigate the intrinsic principle of extracting IPA from DESs, molecular dynamics (MD) simulation method was utilized to acquire the interaction energy between DESs and IPA/ n -heptane, as well as the radial distribution function between DESs and IPA and other kinetic analysis data. The data showed that the experiment is in great assertion with the simulation, DESs synthesized from choline chloride and ethylene glycol has the leading extraction impact of IPA among three kinds of DESs, and Cl - played an imperative part in LLE. In addition, the effect of azeotrope ratio on separation efficiency was explored by simulating LLE with different azeotrope composition.

Study on the technology of efficient extraction of eleutheroside E from Acanthopanax senticosus by green solvent DES.

Acanthopanax senticosus (Rupr. & Maxim.) Harms is a medicinal and edible plant which is clinically used for the recovery and treatment of cardiovascular and central diseases. As a characteristic active pharmaceutical ingredient of Acanthopanax senticosus, eleutheroside E is the core of the therapeutic effect. Organic solvent extraction has low selectivity, low extraction rate, difficulty in separation and purification and safety risks. The purpose of this study was to extract the effective component of Acanthopanax senticosus with a new green solvent. In this article, two kinds of deep eutectic solvents (DESs) (DES-1 and DES-2) were synthesised by heating and stirring methods. Eleutheroside E was extracted by ultrasonic extraction with two kinds of DES as extractants and quantitatively analysed by Orbitrap-tandem mass spectrometry (MS/MS). The main results showed that the initial polarity of the DES was similar to that of 60 to 80% ethanol and hydrogen bond donors were the main factors affecting the polarity of DES. In the test, the viscosity of DES was higher than that of ethanol, and even the addition of a small amount of water (10%) caused intermolecular hydrogen bond disruption and redistribution of the solvent, resulting in a significant decrease in solvent viscosity. The solvents in the test group were stable after standing at 5°C in the dark for 100 days. The extraction rate of eleutheroside E by DES solvent was 5-6 times higher than that by ethanol. DES-1 and DES-2 can efficiently extract eleutheroside E. This study developed a new method for the application of the green extraction of eleutheroside E with certain practical significance.

DES Based Efficient Extraction Method for Bioactive Coumarins from Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav.

In this study, a simple and environmentally friendly method was developed for the extraction of seven active coumarins from Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav.(A. dahurica) based on deep eutectic solvents (DESs). Among the 16 kinds of DES based on choline chloride, the DES system with the molar ratio of choline chloride, citric acid, and water as 1:1:2 had the best extraction effect. Ultrasonic-assisted response surface methodology (RSM) was used to investigate the optimal extraction scheme. The results showed that the optimal extraction conditions were a liquid–solid ratio of 10:1 (mL/g), an extraction time of 50 min, an extraction temperature of 59.85 °C, and a moisture content of 49.28%. Under these conditions, the extraction yield reached 1.18%. In addition, scanning electron microscopy (SEM) was used to observe the degree of powder fragmentation before and after extraction with different solvents. The cells of A. dahurica medicinal materials obtained by DES ultrasonic-assisted treatment were the most seriously broken, indicating that DES had the highest efficiency in the treatment of A. dahurica. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) DPPH radical scavenging model was used to evaluate the biological activity of DES extract. The results showed that DES extract had better scavenging ability of DPPH free radical. Therefore, DES is a green solvent suitable for extracting coumarin compounds of A. dahurica, with great potential to replace organic solvents.

Ultrafast fractionation of wild-type and CSE down-regulated poplars by microwave-assisted deep eutectic solvents (DES) for cellulose bioconversion enhancement and lignin nanoparticles fabrication

Genetic engineering is considered a promising approach to decrease “biomass recalcitrance” and enhance the lignin valorization. Caffeoyl Shikimate Esterase (CSE) was recently indicated to play an important role in lignin biosynthesis. However, the effect of this enzyme on poplar lignin structure and subsequent treatment has not been systematically analyzed. In this study, ultrafast microwave-assisted deep eutectic solvents (DES) pretreatment was effectively performed to deconstruct the main components in wild-type (WT) and CSE down-regulated poplar. After pretreatment with two kinds of DES (ethylene glycol-based and glycerol-based DES), the saccharification efficiency of CSE down-regulated poplar was significantly improved, reaching 96.15%. In addition, the yield of DES lignin increased to 62.66% and 72.89% after Ethylene Glycol and Glycerol-based DES pretreatment in CSE poplar woods as compared to WT poplar wood (48.06% and 60.47%). Moreover, structural and morphological variations of lignin after CSE down-regulation and DES pretreatments have been systematically studied by 2D-HSQC, 31P NMR, GPC, SEM, and TEM techniques. Results showed that native lignin from WT and CSE down-regulated poplars had similar structural features excepted for high content of H-type and p-hydroxybenzoate (PB) units in the CSE down-regulated poplar lignin. Furthermore, quantification of different linkages (β-O-4, β-β, β-5, etc.) in native lignin and DES lignin fractions suggested the ultrafast DES fractionation resulted in the significant cleavage of these linkages under glycerol-based DES pretreatment. Meanwhile, the DES lignin from glycerol-based DES pretreatment was found to be small and homogeneous lignin nanoparticles (LNPs). In short, the glycerol-based DES pretreatment is an environmentally benign scheme to produce easily digestible biomass and the LNPs with narrow size distribution. These findings are very important in assessing the fabricability of CSE poplar in the current biorefinery scenario.

Optimization of Extraction Process of Methyl Eugenol and Asarinin in Asarum with Deep Eutectic Solvent Based on the Response Surface Methodology

To explore a green and efficient extraction technology for the extraction of active ingredients of Asarum, the deep eutectic solvent combined with ultrasonic was applied to compare the extraction efficiency of 10 kinds of deep eutectic solvents, taking the extraction rate of methyl eugenol and asarinin as indices. Single-factor experiments were adopted to investigate the influence of molar ratio, liquid-to-solid ratio, eddy time, ultrasonic time, and temperature of the deep eutectic solvent on the extraction rate of methyl eugenol and asarinin. Based on single-factor experiments, the surface response methodology was used to optimize the extraction process conditions. The results showed that the optimum extracting process conditions of methyl eugenol and asarinin in Asarum consisted of a ratio of choline chloride to glycerol of 1 : 3, a DES volume of 2 mL, an ultrasonic temperature of 60°C, an ultrasonic time of 30 min, and a vortex oscillation of 7 min. Under the optimum extracting process conditions, the contents of methyl eugenol and asarinin were 1.9428 mg/g and 0.9989 mg/g, respectively, and the comprehensive index was 2.3280 (RSD of 1.91%). The results were close to the predicted values of the response surface model, demonstrating the applicability of the model. The extraction rate of methyl eugenol and asarinin in Asarum by this method was higher than that of water extraction and alcohol extraction, which fully indicated the high efficiency of ultrasonic-assisted green deep eutectic solvent extraction technology. The results provide data support for further development and utilization of Asarum.

Capture of Acidic Gases from Flue Gas by Deep Eutectic Solvents

Up to now, many kinds of deep eutectic solvents (DESs) were investigated for the capture of acidic gases from flue gases. In this review, non-functionalized and functionalized DESs, including binary and ternary DESs, for SO2, CO2 and NO capture, are summarized based on the mechanism of absorption, physical interaction or chemical reaction. New strategies for improving the absorption capacity are introduced in this review. For example, a third component can be introduced to form a ternary DES to suppress the increase in viscosity and improve the CO2 absorption capacity. DESs, synthesized with halogen salt hydrogen bond acceptors (HBAs) and functionalized hydrogen bond donors (HBDs), can be used for the absorption of SO2 and NO with high absorption capacities and low viscosities after absorption, due to physicochemical interaction between gases and DESs. Emphasis is given to introducing the absorption capacities of acidic gases in these DESs, the mechanism of the absorption, and the ways to enhance the absorption capacity.

Arecanut (Areca catechu L.) seed extracts extracted by conventional and eco-friendly solvents: Relation between phytochemical compositions and biological activities by multivariate analysis

Arecanut (Areca catechu L.) seed is an important by-product of commercial crop Arecanut planted in tropical or sub-tropical regions. This study for the first time investigated the phyto-chemical compositions and bio-activities of the Arecanut seed extracts extracted by conventional solvents and deep eutectic solvents (DESs). Results showed that the Arecanut seed extracts obtained by the screened DESs exhibited the highest total alkaloid content (TAC, 33.92 mg ARE/g DW), moderate total phenolic content (TPC) and total flavonoid content (TFC). However, high TPC (57.92 mg GAE/g DW) and TFC (427.56 mg RE/g DW) were obtained by acetone and 50 % EtOH, respectively. Ethyl acetate extracts yielded the lowest TPC (0.74 mg GAE/g DW), TFC (4.24 mg RE/g DW) and TAC (0.62 ARE/g DW). A total of 32 compounds (phenolics, flavonoids, and alkaloids) were identified in the Arecanut seed extracts by using high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF/MS) method. Among them, gallic acid, (-)-gallocatechin, (-)-epigallocatechin, D-catechin, isorhamnetin-3-O-galactoside, arecaine, arecoline, and guvacoline were the main compounds. Additionally, two kinds of DESs (L-Proline-Ethylene glycol and L-Proline-Lactic acid) extracts exhibited superior properties on 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS+), hydroxyl (OH−) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activities, ferric reducing antioxidant power (FRAP), reducing power, cupric reducing antioxidant capacity (CUPRAC), inhibitory ability of α-glucosidase and anti-bacterial activity as compared with the extracts extracted by other solvents. Multivariate analysis results revealed that the extraction solvents significantly affected the phytochemical constituents and biological activities of the Arecanut seed extracts. In conclusion, Arecanut seed is a potential source enriched in natural antioxidants for application in the medicinal aspects. Additionally, the present work provided eco-friendly DESs for high-efficient extracting the useful active compounds from Arecanut seed.

Application of deep eutectic solvents modified oxidized Hydrogen-substituted graphyne in adsorption and electrochemistry

Deep eutectic solvents (DES), as the reaction medium, had gained considerable attention in the fabrication of advanced carbon nanostructure materials due to their designability. Here, a DES-mediated strategy was investigated to modify the oxidized hydrogen-substituted graphyne (O-HsGY). Ten kinds of DES based on choline chloride were used to modify O-HsGY and improve its adsorption and electrochemical performance. The morphology of DES-mediated oxidized hydrogen-substituted graphyne (DES-O-HsGY) were characterized by field emission-scanning electron microscopy (FE-SEM) and showed some cavity structure. Brunauer Emmett teller and X-ray diffraction characterization confirmed that the material had a relatively average pore size and a wide layer spacing (0.388 nm), which was conducive to ion transport. The adsorption and electrochemical properties of DES-O-HsGY were also studied and presented the excellent performance. The DES (Choline chloride: Ethylene glycol, 1:2) modified material had the best adsorption performance for thiabendazole, and the maximum adsorption value was 0.85 mg/g. The obtained electrochemical testing results proved that the cyclic voltammetry characteristic curve of the modified material not only had stability and deformation resistance at high scanning rate of 300 mV/s, but also had good conductivity. Therefore, the DES-mediated oxidized hydrogen-substituted graphyne had the promising prospect in the field of adsorption and electrochemistry.

Deep eutectic solvents with multiple weak acid sites for highly efficient, reversible and selective absorption of ammonia

Developing new NH3 separation technology is very meaningful for the environmental protection related to ammonia synthesis process. In this work, we found that ethylamine chloride (EaCl) can form deep eutectic solvents (DESs) with resorcinol (Res) and phloroglucinol (Phl). The chemical and physical properties of new DESs were determined first, because they are the basic data for DESs. Considering that such kinds of DESs have multiple weak acid sites, we systematically investigated the NH3 absorption performance of prepared DESs. We found that the prepared DESs show chemical absorption for NH3, with quite high NH3 solubilities, particularly at reduced pressures. Specifically, the solubilities of NH3 in prepared DESs reach 9.00 mol/kg at 313.2 K and 102.1 kPa, and 3.73 mol/kg at 313.2 K and 4.7 kPa. The prepared DESs also show highly reversible absorption for NH3, and selective absorption towards N2 and H2. The underlying mechanism of prepared DESs for NH3 absorption was finally investigated by theoretical calculations and spectroscopic characterizations.

Microwave-assisted deep eutectic solvents (DES) pretreatment of control and transgenic poplars for boosting the lignin valorization and cellulose bioconversion

Reducing the “biomass recalcitrance” and simultaneously improving the efficiency of deconstruction and conversion is vitally important in a biorefinery process. Herein, a microwave-assisted deep eutectic solvents (DES) pretreatment was developed to deconstruct the control and transgenic (C3H, HCT and C3H + HCT co-inhibition) poplars, and improve the lignin extractability and valorization. NMR and GPC results showed that native lignin (Double Enzymatic Lignin, DEL) in different poplars exhibited slightly different structural characteristics, affecting the subsequent lignin extractability and value-added applications. After two kinds of DES (ethylene glycol-based and glycerol-based DES) pretreatments, the yield of DES lignin was obviously increased to 45.38–53.09 % and 46.38–54.30 % in transgenic poplar woods as compared to control poplar wood (37.25 and 38.86 %). In addition, molecular weight, and abundances of different linkages (β-O-4, β-β, β-5, etc.) in the DES lignin fractions were significantly decreased, suggesting the microwave-assisted DES pretreatment has a strong deconstruction ability towards to poplar wood. Moreover, the rapid and efficient pretreatment facilitated the isolation of the lignin fractions from transgenic poplars, and the regenerated DES lignin fractions exhibited excellent antioxidant properties, which will lay the foundation for the lignin valorization. Furthermore, the enzymatic saccharification ratios of the DES pretreated substrates were significantly increased to 87.36–96.55 % in control and transgenic poplar woods, indicating that microwave-assisted DES pretreatment indeed boosted cellulose bioconversion. In short, the combination of genetic modification and DES pretreatment can significantly reduce the “biomass recalcitrance” and promote the biomass valorization.

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.

Facile and rapid fractionation of bamboo wood with a p-toluenesulfonic acid-based three-constituent deep eutectic solvent

Here, we report a strategy with the application of p-toluenesulfonic acid (p-TsOH) based three-constituent deep eutectic solvent (3c-DES) for the efficient fractionation of bamboo wood towards its main components. Three kinds of deep eutectic solvents (DESs), including choline chloride (ChCl)/ ethylene glycol (EG)/p-TsOH, tetrabutylammonium chloride (N4Cl)/EG/p-TsOH and tetrapropylammonium chloride (N3Cl) /EG/ p-TsOH, were facilely prepared and assessed for the pretreatment of bamboo wood. ChCl-EG-p-TsOH (molar ratio of 1:0.5:1) was found to be the most effective, evidenced by more than 93.36% xylan and 90.32% lignin removals with most of the cellulose (86.73%) retained in the pretreated bamboo in a short time of 10 min at 100 °C and a 10 wt. % solid loading, which significantly improved delignification by more than 85% compared with that of using ChCl-EG (molar ratio of 1:2) as a two-constituent at the same conditions. The 3c-DES pretreatment resulted in the desirable deconstruction of the recalcitrant of cell walls in woody biomass, evidenced by the higher glucose yield of 90.2% by the enzymatic hydrolysis of the cellulose-rich substrate, which was nearly four-fold higher than that of the untreated bamboo. The extracted lignin showed high purity (95%) with a moderate and homogeneous molecular weight, showing promising potential applications in the downstream production of biochemicals and biomaterials. Furthermore, the 3c-DES exhibited excellent recoverability by evaluating the fractionation efficiency and enzymatic hydrolysis performance with the recycled DES. The results from this study demonstrated that p-TsOH-based 3c-DES showed practical significance for the fast and effective fractionation of woody biomass for high-quality components.

Extraction of Flavonoids from Scutellariae Radix using Ultrasound-Assisted Deep Eutectic Solvents and Evaluation of Their Anti-Inflammatory Activities.

Deep eutectic solvents (DESs) play important roles in the extraction of active constituents in traditional Chinese medicine. Ultrasound-assisted DES has been used to extract flavonoids from Scutellaria baicalensis. Using the contents of scutellarin, baicalin, baicalein, wogonoside, wogonin, and oroxylin A as quantitative indices, different kinds of DESs have been optimized for extraction and betaine/acetic acid has shown the highest yield. The Box–Behnken response surface method (RSM) was utilized to select the extraction conditions with the highest yields. The optimal extraction conditions were as follows: the molar ratio of betaine/acetic acid was 1:4, the water content was 40%, the solid/liquid ratio was 1:100 g/mL, the extraction temperature was 52 °C, and the extraction time was 23 min. Compared with traditional reflux extraction using 70% ethanol as the solvent, ultrasound-assisted DES has a shorter extraction time and higher yields. Furthermore, anti-inflammatory activities of the two extracts by ultrasound-assisted DES and reflux were compared using RAW264.7 cells and the methyl thiazolyl tetrazolium (MTT) method, and they showed equal anti-inflammatory activities. The results demonstrated that the ultrasound-assisted DES method for extraction of flavonoids from scutellariae radix is simple, green, efficient, and reproducible. This research provides good method guides for the rapid and efficient extraction of flavonoids from natural sources.

Green and enhanced extraction of coumarins from Cortex Fraxini by ultrasound-assisted deep eutectic solvent extraction.

Green and enhanced extraction of bioactive ingredients from medicinal plants has become a hot research field, and deep eutectic solvents have been considered as a novel kind of sustainable solvents in the extraction process. In this study, hydrogen bond acceptor (choline chloride, etc.) and hydrogen bond donor (l-malic acid, etc.) were used to prepare different kinds of deep eutectic solvents to extract coumarins from Cortex Fraxini. The extraction conditions, including the composition and moisture content of deep eutectic solvents, extraction time, and liquid-solid ratio, were systematically optimized basing on the extraction yield of coumarins. To further investigate the extraction mechanism, Fourier transform infrared spectroscopy was performed, and the microstructures of Cortex Fraxini powders were observed before and after extraction using scanning electron microscope. Results showed that the novel ultrasound-assisted extraction with conditions of deep eutectic solvent containing betaine/glycerin (1:3), aqueous solution (20%), solid-liquid ratio (15mg/mL), and extraction time (30min) exhibited the best extraction yields for the four target coumarins and much better extraction efficiency than with conventional solvent extractions. This suggests that the new ultrasound-assisted deep eutectic solvent extraction could be used as a green and high-efficient approach for extraction of the main coumarins from Cortex Fraxini.

Absorptive Desulfurization of Model Biogas Stream Using Choline Chloride-Based Deep Eutectic Solvents

The paper presents a synthesis of deep eutectic solvents (DESs) based on choline chloride (ChCl) as hydrogen bond acceptor and phenol (Ph), glycol ethylene (EG), and levulinic acid (Lev) as hydrogen bond donors in 1:2 molar ratio. DESs were successfully used as absorption solvents for removal of dimethyl disulfide (DMDS) from model biogas steam. Several parameters affecting the absorption capacity and absorption rate have been optimized including kinds of DES, temperature, the volume of absorbent, model biogas flow rate, and initial concentration of DMDS. Furthermore, reusability and regeneration of DESs by means of adsorption and nitrogen barbotage followed by the mechanism of absorptive desulfurization by means of density functional theory (DFT) as well as FT-IR analysis were investigated. Experimental results indicate that the most promising DES for biogas purification is ChCl:Ph, due to high absorption capacity, relatively long absorption rate, and easy regeneration. The research on the absorption mechanism revealed that van der Waal interaction is the main driving force for DMDS removal from model biogas.

Application of choline-based deep eutectic solvent for the extraction of crude-oil contaminated soils

ABSTRACT Choline-based deep eutectic solvents (DESs) have many outstanding features as they are easy to prepare, inexpensive, low-toxic, low volatile, and biodegradable, which make them increasingly attractive in industrial chemistry and green chemistry. In this paper, the abilities of three different kinds of DESs for crude oil removal from contaminated soils were compared and it was found the DES formed by phenylpropionic acid and choline chloride (mole ratio = 2:1) had the best performance. The effects of extraction time, temperature and the solvent–soil ratio on phenylpropionic acid/choline chloride DES performance were evaluated. The rational extraction conditions were recommended as follows: mass ratio of DES to soil was 10:1 and 60 min extraction time at 80°C. The extraction (desorption) process could be described by Freundlich desorption isotherm mode. In addition, the phenylpropionic acid/choline chloride DES could be recycled and the oil removal efficiency was about 90% after 10 cycles. This finding suggested that choline-based DES extraction was a promising technology for crude oil removal from contaminated soil.