Betaine-based Deep Eutectic Solvents Research Articles

Extraction of oleanolic acid from wine pomace using betaine-based deep eutectic solvents

Extraction of oleanolic acid from wine pomace using betaine-based deep eutectic solvents

Extraction and characterisation of kudzu root residue lignin based on deep eutectic solvents.

Lignin has great potential as the most abundant renewable phenolic polymer. Studies have shown that lignin structure varies depending on different sources and different extraction methods. However, there are few studies on lignin in kudzu root residue. The aim of the study was to explore optimal extraction conditions of Pueraria lobata residue lignin (PLL) with deep eutectic solvents (DESs) and characterise the structure and morphology of PLL. Firstly, the chemical composition of kudzu root residue was determined by the Van-soest method. Then, betaine was used as hydrogen bond acceptor (HBA), nine kinds of common acids and alcohol were selected as hydrogen bond donor (HBD) to synthesise a DES to extract lignin from kudzu root residue. The influence of conditions on the extraction of PLL was explored by a betaine-based DES according to a single-factor experiment, and then the best process of PLL extraction was determined by an orthogonal experiment. Finally, the morphology and structure of PLL were analysed by scanning electron microscope (SEM), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and NMR. Cellulose, hemicellulose, lignin, and ash content in kudzu root residue were 41.13%, 16.39%, 25.03%, and 0.41%, respectively. When the DES consisted of betaine and formic acid, the solid-liquid ratio was 1:45, the extraction time was 5.5 h at 160°C, the extraction yield of lignin was 89.29%, and the purity was 83.01%. PLL was composed of interconnected spherical particles with good thermal stability and narrow polydispersity index (PDI) distribution. FTIR and 2D-heteronuclear singular quantum correlation (HSQC) NMR illustrated that PLL was a typical G-type and S-type lignin. This study would fill the gap of research on lignin in kudzu root residue and provide a theoretical reference for the utilisation of lignin in kudzu roots as well as a new thinking for the recycling of kudzu root resources.

Determination of the solubility profile of isophthalic acid in some aqueous solutions of betaine-based deep eutectic solvents: Study the extent of H-bonding interactions between starting materials of deep eutectic solvents in aqueous medium

The equilibrium solubility of isophthalic acid (IPA) in three aqueous solutions of betaine/propylene glycol (Bet/PG, 1:5 M ratio), betaine/ethylene glycol (Bet/EG, 1:3 M ratio) and betaine/glycerol (Bet/Gly, 1:3 M ratio) deep eutectic solvents (DESs) (1) was determined experimentally by utilizing a shake-flask method at 293.15–313.15 K covering the whole composition range at atmospheric pressure (≈85 kPa). For three investigated systems, an increase in solubility was observed by decreasing water mass fraction; so that, the lowest and highest solubilities were in water at 293.15 K and pure DESs at 323.15 K, respectively. Also, the mixtures containing PG presented the higher values of the solubility than that of EG or Gly which may be attributed to its lower dipole moment and dielectric constant (2.27 D, 32.0) than the others. By representation the derived equilibrium solubilities with models of Jouyban-Acree, Jouyban-Acree-van't Hoff, NRTL and Wilson a maximum overall mean relative deviation of 15.9% was achieved. Moreover, the solubilities of IPA in ternary (Bet + PG, EG or Gly + water) mixtures at 298.15 were measured to investigate the extent of H-bonding interactions of Bet with PG, EG or Gly into DESs in the presence of water by comparing IPA solubility data for each binary (DES + water) system and the corresponding ternary mixtures. The results suggested that the H-bonding interactions between two components of DESs were disappeared when the water content was exceeded 60% (g/g). This result more explored by recording 1H NMR spectra of diluted DESs with deuterium dioxide. Eventually, an endothermic and enthalpy-driven process in most mixtures was determined by thermodynamic analysis of IPA dissolution and mixing processes based on the modified van't Hoff equation.

Comparison of physicochemical and thermal properties of choline chloride and betaine-based deep eutectic solvents: The influence of hydrogen bond acceptor and hydrogen bond donor nature and their molar ratios

Within the green chemistry area, deep eutectic solvents (DESs) are playing an increasingly prominent role thanks to their intriguing physicochemical properties. However, a comparative study encompassing a wide range of properties as a function of different parameters such as the nature of the hydrogen bond acceptor (HBA) and donor (HBD) and their molar ratio is still missing. In this work, six DESs based on the most used HBAs (choline chloride (ChCl) and betaine (Bet)) and HBDs (ethylene glycol (EG), glycerol (Gly) and levulinic acid (LevA)) combined in three different molar ratio (1:2, 1:3, 1:4) have been prepared and subjected to a series of analysis aimed at measuring different properties such as density, viscosity, refractive index, thermal stability and thermal behaviour. The most striking findings see the EG-based DESs displaying the lowest density and viscosity values, while the Gly-based DESs exhibited the highest. High viscosity and density have been obtained using Bet instead of ChCl as HBA. Increasing the amount of HBD in DESs caused lower viscosity in all cases, while density increased for all Gly-based DESs and decreased for EG and LevA-based DESs. The refractive index also decreased when the HBD portion was increased. However, higher refractive index was obtained using ChCl instead of Bet as HBA. The temperature and wavelength dependence of the refractive index is otherwise described pretty well by a Sellmeier model. The molar refractivity implied by density and refractive index data via the Clausius-Mossotti equation is consistent with that predicted by the empirical but well-established model of Wildman and Crippen.The short thermal stability of all investigated DESs is strictly related to the HBD used. EG-based DESs were less stable than LevA-based ones while Gly-based DESs were the most stable materials. Moreover, for all DESs three characteristic mass loss events have been identified. They can be attributed to the evaporation/degradation of the HBD, of the intimately interacting HBD-HBA and of the HBA, respectively. Finally, DSC analyses showed that all DESs can be used as solvents given that they are liquids at room temperature, and they maintain a liquid state in a broad range of temperatures (Tg < −50 °C or no thermal events are observed).

Effect of temperature and composition on solubility and thermodynamics of salicylic acid in aqueous mixtures of betaine-based deep eutectic solvents

Effect of temperature and composition on solubility and thermodynamics of salicylic acid in aqueous mixtures of betaine-based deep eutectic solvents

High-Value Bioconversion of Ginseng Extracts in Betaine-Based Deep Eutectic Solvents for the Preparation of Deglycosylated Ginsenosides.

Deep eutectic solvents (DES), as a green alternative to traditional organic solvents in biocatalysis, not only activate proteins but even increase the efficiency of enzymatic reactions. Here, DES were used in a combinatorial enzyme-catalyzed system containing β-glucosidase BGLAt and β-galactosidase BGALAo to produce deglycosylated ginsenosides (De-g) from ginseng extracts (GE). The results showed that DES prepared with betaine and ethylene glycol (molar ratio, 1:2) could significantly stimulate the activity of the combinatorial enzymes as well as improve the acid resistance and temperature stability. The DES-based combinatorial enzyme-catalyzed system could convert 5 g of GE into 1.24 g of De-g (F1, F2, 20 (S)-PPT, and CK) at 24 h, which was 1.1 times that of the buffer sample. As confirmed by the spectral data, the changes in the conformations of the combinatorial enzymes were more favorable for the binding reaction with the substrates. Moreover, the constructed DES-based aqueous two-phase system enabled the recovery of substantial amounts of DES and De-g from the top phase. These results demonstrated that DES shows great application as a reaction solvent for the scale-up production of De-g and provide insights for the green extraction of natural products.

Comprehensive exploration of the adsorption capacity of innovative betaine-based deep eutectic solvents for carbon dioxide capture

Compared with traditional organic solvents and ionic liquids, deep eutectic solvents (DESs) as innovative emerging solvents has attracted widespread attentions in the field of CO2 absorption due to its remarkable advantages, such as low melting point, cheapness, easy preparation, regeneration and biodegradation. Herein the halogen-free DESs constituting of betaine as hydrogen bond acceptor, 1,2-propanediol and diethylene glycol as hydrogen bond donor were employed to absorb CO2. The CO2 absorption capacity of DESs with different molar ratios was measured at a certain temperature (303.15–348.15 K) and pressure (180–770 kPa). The results show that the solubility of CO2 in DESs can be improved by decreasing the temperature and increasing the pressure. The solubility of CO2 in DESs increases with increasing mole ratio of 1,2-propanediol, but decreases with increasing mole ratio of diethylene glycol. The Jou and Mather model was used to calculate the CO2 solubility data, which was compared with the experimental results. Through the estimated Henry's constant, the gibbs free energy, enthalpy and entropy of absorption were calculated and the results indicate that the CO2 dissolution in DESs is a non-spontaneous exothermic process. Regeneration can be achieved by depressurizing and heating the DES-CO2 system. By comparing with the Henry's constant Hm of the reported solvents, this work provides the possibility and space for further optimizing the use of new materials DESs to capture CO2.

Solubility of mesalazine in aqueous solutions of two betaine-based deep eutectic solvents at different temperatures: Data correlation and thermodynamic analysis

Temperature-dependent solubility data for mesalazine in the cosolvency systems composed of water and deep eutectic solvents (DESs) obtained from betaine as a hydrogen bond acceptor and ethylene glycol (EG) or propylene glycol (PG) as hydrogen bond donors were determined by a shake flask technique at 293.15–313.15 K under atmospheric pressure (≈ 85 kPa). Based on the results, type of hydrogen bond donor plays an important role in solubilization power of DESs for mesalazine; so that, the values of mesalazine solubility in betaine/EG DES + water mixtures were higher than that the other. It was also found that the solubility of mesalazine in the investigated mixtures increased by increasing mass fractions of DESs as well as enhancing temperature reaching to the maximum values in neat DESs at 313.15 K. The Hansen solubility parameters for mesalazine, neat solvents of betaine/EG or betaine/PG DESs and water were calculated to predict the solubility of drug in the investigated systems. Moreover, X-ray powder diffraction was served to analyze the equilibrium solid phase crystal of mesalazine and the results turns out that no polymorphic transformation or crystal transition during the whole solvent crystallization process. The solubility data were then represented with some cosolvency models (Jouyban-Acree, Jouyban-Acree-van’t Hoff and so on) and activity coefficient models (NRTL, Wilson and UNIQUAC). According to the calculated percentage averaged relative deviations (ARD%) for back-calculated data, all the studied models present good correlation. Additionally, an endothermic and enthalpy-driven process for mesalazine dissolution in aqueous mixtures of betaine-based DESs obtained from apparent thermodynamic analysis.

Experimental determination and correlation of naproxen solubility in biodegradable low-toxic betaine-based deep eutectic solvents and water mixtures at 293.15 K to 313.15 K

For enhancement the low bioavailability of poorly water-soluble naproxen, three deep eutectic solvents (DESs) obtained from betaine as a hydrogen bond acceptor and propylene glycol, ethylene glycol or glycerol as a hydrogen bond donor (Bet/PG, Bet/EG or Bet/Gly DESs) are utilized from 0.0 to 1.0 mass fractions of DESs at T = (293.15–313.15) K under atmospheric pressure (≈ 85 kPa). The solubility values tend to enhance with enhancing mass fraction of each DES as well as increasing temperature and the maximum values are obtained in the highest mass fraction of DESs at 313.15 K. Besides, the Hansen solubility parameters are used to predict the selection of appropriate cosolvent system; the results indicated that the Bet/PG DES is a proper cosolvent for naproxen solubilization. Moreover, the equilibrated solid phase crystal of naproxen with neat solvents is characterized with X-ray powder diffraction analysis to identify no polymorphic transformation, solvate formation or crystal transition during the whole solvent crystallization process. In addition, the experimental solubilities are correlated with the temperature dependency of traditional cosolvency models including Jouyban-Acree, Jouyban-Acree-van't Hoff and modified Wilson-van't Hoff together with the activity coefficient models of NRTL, Wilson and UNIQUAC. The accuracies of the calculated solubilities are evaluated by calculation of the mean relative deviation (MRD%) and the results suggested that the Jouyban-Acree (MRD% ≤ 8.9) along with the NRTL activity coefficient model (MRD% ≤ 2.0) are more accurate than the others. Finally, the respective apparent thermodynamic quantities of the dissolution and mixing processes, namely Gibb's energy, enthalpy, and entropy are calculated based on the van't Hoff and Gibbs equations.

Extraction of essential oils from tea tree (Melaleuca alternifolia) and lemon grass (Cymbopogon citratus) using betaine-based deep eutectic solvent (DES).

The essential oils of tea tree (Melaleuca alternifolia) leaves mainly contain eucalyptol, α-terpinene, -terpinene, and terpinen-4-ol and have anti-bacterial, anti-fungal, anti-infective, and anti-inflammatory actions. The essential oils of lemon grass (Cymbopogon citratus) leaves mainly contain neral, geranial, and geraniol and have anti-microbial and anti-fungal activities and hypocholesterolemic effect. The present study describes the use of low-toxicity solvents called betaine-based deep eutectic solvents (DESs) for efficient extraction of essential oils from tea tree and lemon grass. H2 O and EtOH were used for extraction as control methods. Quantitative analysis was performed using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode. Scanning electron micrography (SEM) and antioxidant assays for extracted samples were also conducted. The results indicated that extraction for tea tree using betaine/sucrose (molar ratio 2:1) improved the yields of terpinolene and eucalyptol 2.5- and 1.9-fold, respectively, compared with the control method. In lemon grass, extraction using betaine/sucrose (molar ratio 2:1) improved the yields of neral and geranial 1.9- and 1.7-fold, respectively, compared with the control method. These results demonstrated the effective extraction of essential oils from plant leaves under milder conditions than those needed for the conventional methods. The environmentally benign DESs for the extraction would be applicable to the food and cosmetic industries.

Betaine-based deep eutectic solvents mediated synthesis of zinc oxide nanoparticles at low temperature

Deep eutectic solvents (DES) are gaining popularity as a potential substitute for ionic liquids because of their lower cost and biodegradability. Betaine and phenol with melting points ∼300 °C and ∼43 °C, respectively, combine with a molar ratio of 1:2 to form a liquid at room temperature with a eutectic melting point of ∼20 °C. ZnO nanoparticles (NPs) were synthesized by using an eco-friendly and green synthesis method utilizing betaine-based DES at low temperature ∼80 °C for 2 h. X-ray diffraction analysis confirms the highly crystalline and single-phase formation of ZnO NPs with hexagonal-Wurtzite phase structure. The surface morphology of the ZnO NPs confirmed using scanning electron microscopic images revealing the mostly spherical in shape and some n-pointed stars and transmission electron microscopy images confirms that NPs are sub-100 nm in range. Also, energy dispersive X-ray results confirm the elemental composition of Zn K (∼8.6 keV) and O K (0.52 keV) to be ∼88.5 ± 1.7% and 11.5 ± 1.3%, respectively. Fourier transform infrared spectroscopy confirms the bands at 565 and 410 cm−1 is assigned to asymmetric stretching and bending vibrations of the Zn–O tetrahedron. Thermogravimetric analysis verified the thermal stability with phase purity, resulting in the formation of the single-phase crystalline ZnO NPs. UV–Vis absorption study confirms the bandgap of ∼3.1 eV. The high stability and dispersion of NPs in water confirms the interaction of DES molecules on the surface of the NPs with water. ZnO NPs incorporated in PVA thin films show strong UV–Vis absorption confirming use of these transparent thin films for UV-shielding applications. As far as we know, this study is unique, green, eco-friendly and cost-effective in that the authors were able to synthesize ZnO NPs from betaine-based DES.

Recycling of full components of polyester/cotton blends catalyzed by betaine-based deep eutectic solvents

The development of an environmental methodology for polyethylene terephthalate (PET) degradation and separation from cotton is significant for the full utilization of waste polyester/cotton blends (PCBs). Therefore, it is crucial to find a catalyst that can efficiently catalyze PET degradation and completely separate from cotton. In this work, betaine based deep eutectic solvents (DESs) were first synthesized and innovatively used for selective degradation of PET fibers from PCBs. As a result, PET fiber was degraded completely, a purified monomer bis (2-hydroxyethyl terephthalate) (BHET) with a yield of 85% was obtained that could be repolymerized to produce PET, and 95% of the cotton was recycled and maintained its original structural integrity. Meanwhile, the synergistic mechanism was also proposed by in-situ IR, 1H‐NMR and DFT calculations. This work provides a new approach to recycle full components of waste PCBs.

Thermodynamic study of the aqueous pseudo-binary mixtures of betaine-based deep eutectic solvents at T = (293.15 to 313.15) K

ABSTRACT This work investigates physicochemical properties of betaine/propylene glycol (Bet/PG) and betaine/ethylene glycol (Bet/EG) DESs in water by measuring their densities in neat state and aqueous mixtures over the entire composition range at T = (288.15–318.15) K under atmospheric pressure (≈ 85 kPa). The obtained values of density were used to compute the excess molar volumes (), molar volume (V m), apparent molar volume (), limiting apparent molar expansibility () and the isobaric thermal expansion coefficient (). The solute-solvent interactions in the investigated solutions are evaluated on the basis of these important physicochemical properties. The results indicated that two studied DESs act as a structure-making solute in water over the whole temperature range using Hepler’s constant. Finally, the experimental densities were correlated with some models including Jouyban-Acree, Jouyban-Acree-van’t Hoff, modified Jouyban-Acree-van’t Hoff, Redlich-Kister and Emmerling. The Redlich-Kister expression and Jouyban-Acree model were also used for representation of values.

Comprehensively Explore Adsorption Capacity of Innovative Betaine-Based Deep Eutectic Solvents for Carbon Dioxide

Comprehensively Explore Adsorption Capacity of Innovative Betaine-Based Deep Eutectic Solvents for Carbon Dioxide

Green extraction of apigenin and luteolin from celery seed using deep eutectic solvent

In recent years, deep eutectic solvent (DES) has attracted a great deal of attention as an environmentally friendly solvent and could be used as an alternative to conventional solvents. In this study, 34 choline and betaine-based deep eutectic solvents were prepared and investigated the ability to extract apigenin and luteolin from the celery seed. The results showed that DES composed of betaine hydrochloride and propylene glycol had the best extraction efficiency. Using one factor at a time combined with response surface methodology, the optimal conditions of extraction were determined as follows: time of extraction: 19 min, extraction temperature: 75 °C, the water content in solvent: 40% (w/w). Antisolvent (water) combined with distillation was proposed as an efficient method to recover apigenin and luteolin from the DES extract. The relationship between components of DES and solubility of apigenin, luteolin was also established which was the starting point for the prediction of extractability of DES. Molecular dynamics revealed that betaine hydrochloride and propylene glycol could interact with each other by the formation of two types of hydrogen bond while water molecules might play an important role in the ability to dissolve apigenin and luteolin of DES.

Effective Extraction of Limonene and Hibaene from Hinoki (Chamaecyparis obtusa) Using Ionic Liquid and Deep Eutectic Solvent.

The essential oils of hinoki (Chamaecyparis obtusa) leaves have anti-bacterial, anti-fungal, and relaxation properties that are likely associated with the major components such as sabinene, α-terpinyl acetate, limonene, elemol, myrcene, and hibaene. The present study describes the use of a cellulose-dissolving ionic liquid (IL) [C2mim][(MeO)(H)PO2] and low-toxicity solvents called betaine-based deep eutectic solvents (DESs) for the efficient extraction of hinoki essential oils. As a control method, organic solvent extraction was performed using either hexane, ethyl acetate (EtOAc), or acetone at 30 °C for 1 h. Both the experimental and control methods were conducted under the same conditions, which relied on partial dissolution of the leaves using the IL and DESs before partitioning the hinoki oils into the organic solvent for analysis. Quantitative analysis was performed using gas chromatography–mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. The results indicated that extraction using the [C2mim][(MeO)(H)PO2]/acetone bilayer system improved the yields of limonene and hibaene, 1.5- and 1.9-fold, respectively, when compared with the control method. In addition, extraction using betaine/l-lactic acid (molar ratio 1:1) gave the greatest yields for both limonene and hibaene, 1.3-fold and 1.5-fold greater, respectively, than when using an organic solvent. These results demonstrate the effective extraction of essential oils from plant leaves under conditions milder than those needed for the conventional method. The less toxic and environmentally begin DESs for the extraction are also applicable to the food and cosmetic industries.

Understanding the Formation of Deep Eutectic Solvents: Betaine as a Universal Hydrogen Bond Acceptor.

The mechanism of formation of betaine-based deep eutectic solvents (DES) is presented for the first time. Due to its polarity unbalance, it was found that betaine displays strong negative deviations from ideality when mixed with a variety of different organic substances. These results pave the way for a comprehensive design of novel deep eutectic solvents. A connection to biologically relevant systems was made using betaine (osmolyte) and urea (protein denaturant), showing that these two compounds formed a DES, the molecular interactions of which were greatly enhanced in the presence of water.

Choline-chloride and betaine-based deep eutectic solvents for green extraction of nutraceutical compounds from spent coffee ground

Coffee beans contain several compounds which have shown nutraceutial properties; among them chlorogenic acids (CGAs) are the most studied, have shown nutraceutical properties. These molecules are also present in the waste by-product known as spent coffee grounds (SCG). SCG are generated during the production of coffee drink, whereby roasted, ground coffee beans are heat or steam treated. A HPLC-PDA/ESI-MS method has been developed for the analysis of the most representative CGAs in SCG samples using a green extraction approach based on deep eutectic solvents (DESs). We examined fifteen different DESs based on choline chloride and betaine as hydrogen bond acceptor in combination with different hydrogen bond donors being seven alcohols, two organic acids, one sugar and urea. Fifteen CGAs were detected, identified and quantified for the evaluation of extraction efficiency. A betaine-based DES with triethylene glycol (molar ratio 1:2) was the most effective one at extracting CGAs from SCG also compared to a conventional organic solvent. Thirty percent of water added to DES and sample to solvent ratio 1:15 (g/mL) were selected as the best extraction conditions. The chromatographic method was validated studying LOD, LOQ, retention time and peak area precision, and linearity range. Retention time and peak area repeatability were determined obtaining RSDs values below 0.63 % and 8.51 %, respectively. Inter-day precision was determined obtaining RSDs value below 0.58 % and 8.80 % for retention time and peak area, respectively.

Application of deep eutectic solvents for the extraction of phenolic compounds from extra-virgin olive oil.

A HPLC-DAD/ESI-MS method has been developed and validated for the analysis of the most representative phenolic compounds in extra-virgin olive oil (EVOO) samples using a green extraction approach based on deep eutectic solvents (DESs) at room temperature. We examined ten DESs based on choline chloride and betaine in combination with different hydrogen bond donors comprising six alcohols, two organic acids, and one urea. Five phenolic compounds, belonging to the classes of secoiridoids and phenolic alcohols, were selected for the evaluation of extraction efficiency. A betaine-based DES with glycerol (molar ratio 1:2) was found to be the most effective for extracting phenolic compounds as compared to a conventional solvent. The optimization of the extraction method involved the study of the quantity of water to be added to the DES and evaluation of the sample-to-solvent ratio optimal condition. Thirty percent of water added to DES and sample to solvent ratio 1:1 (w/v) were selected as the best conditions. The chromatographic method was validated by studying LOD, LOQ, intraday and interday retention time precision, and linearity range. Recovery values obtained spiking seed oil sample aliquots with standard compounds at 5 and 100μg/g concentration were in the range between 75.2% and 98.7%.

Betaine-based deep eutectic solvents with diol, acid and amine hydrogen bond donors for carbon dioxide absorption

Deep eutectic solvents (DESs) are known as alternative green solvents due to their ease of synthesis, availability, biodegradability and negligible volatility. DESs consisted of betaine as the hydrogen bond acceptor with 1,2-propanediol, levulinic acid and methyl diethanolamine (MDEA) as the hydrogen bond donors, were prepared in 1:3 and 1:6 molar ratios. The carbon dioxide solubilities in these DESs were determined using a volumetric apparatus at 313.15 K and 6 bar. The results show that CO2 solubilities in betaine-based DESs are higher than the reported CO2 solubilities in choline chloride-based DESs, for DESs having the same hydrogen bonding donor and an identical or similar composition. The viscosity and polarity of hydrogen bond donors affected the ability of deep eutectic solvent to absorb carbon dioxide. The betaine-MDEA deep eutectic solvent, with molar ratio of 1:6, has the highest absorption capacity of 0.0814 mol CO2/mol DES, measured at 313.15 K and 6 bar.