Effect Of Deep Eutectic Solvents Research Articles

Synergistic effects of deep eutectic solvents on the morphology and performance of polysulfone ultrafiltration membranes

This study investigates the synthesis of flat sheet asymmetric Polysulfone (PSF) membranes using the Non-Solvent Induced Phase Separation (NIPS) method, enhanced by incorporating Deep Eutectic Solvents (DES) composed of Choline Chloride (ChCl) and DL-Malic Acid (MA). The research explores the individual and combined effects of ChCl and MA on membrane morphology and performance. Comprehensive characterization techniques, including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy-Universal Attenuated Total Reflectance (FTIR-UATR), and Atomic Force Microscopy (AFM), were employed to analyze the structural and surface properties of the membranes. Key performance metrics such as Pure Water Permeability (PWP), protein and dye rejection, fouling behavior, porosity, surface hydrophilicity, and mechanical strength were evaluated. Results demonstrated that integrating DES into the PSF matrix significantly improved membrane properties. The 3% DES membrane exhibited the highest Pure Water Permeability (PWP) of 186.82 L/m2h/bar, the lowest water contact angle of 68.8°, and optimal balance in surface roughness parameters, leading to superior antifouling properties with high flux recovery ratio (FRR) and balanced reversible (Rr) and irreversible fouling (Rir) components. The ChCl (HBA) membrane displayed a notable PWP of 121.62 L/m2h/bar, large pore sizes (42.72 nm), and moderate surface roughness (Ra of 3.32 nm). In contrast, the MA (HBD) membrane demonstrated the highest hydrophilicity with the lowest contact angle (70.7°) and a compact, robust structure, despite its smallest pore sizes and lack of permeability. The findings underscore the synergistic effect of DES formation in the membrane, improving overall performance for ultrafiltration applications. This study provides valuable insights into the distinct roles of ChCl as an HBA and MA as an HBD in DES-modified PSF membranes, revealing their individual contributions and the importance of optimizing DES components and concentrations for specific filtration applications.

Solubility effect of deep eutectic solvent and ethanol concentration on corncob lignin extraction

This research investigates the solubility effect of deep eutectic solvent (DES) mass ratio and ethanol–water solution concentration on corncob lignin extraction. The objective is to propose a solubility matching technique based on like-dissolves-like theory to optimize lignin extraction conditions. The choline chloride (ChCl):lactic acid (LA) mass ratio that maximized lignin extraction was determined by varying DES mass ratio between 1:2 and 1:5, and ethanol–water solution (5–95 % (v/v)) was added to precipitate lignin. By using the solubility matching technique, the maximum lignin extraction was achieved at 1:4 ChCl:LA mass ratio, and 70 % (v/v) ethanol–water concentration yielded the highest lignin precipitation. Lignin is highly soluble where the solubility (δ-values) of lignin, DES, and precipitant are similar. Unlike conventional trial-and-error methods, the solubility matching technique relies on δ-values calculated by the Hildebrand and Scott equation. The proposed technique can also be applied to optimize the extraction conditions of other biomass materials.

Extraction of bioactive compounds from peel and seeds of pitomba (Talisia esculenta) using eutectic solvents

SummaryThis study explores using pitomba peel and seeds to obtain a natural extract with high antioxidant capacity, employing extraction techniques with eutectic solvents combined with agitation and temperature control. The analysis revealed that, for the extraction with pitomba peel residues, the average levels of phenolic compounds did not show significant differences except for the extraction with ethanol. In contrast, the extractions performed with pitomba seeds showed significant differences, with the combination of choline chloride with lactic acid and choline chloride with glycerol providing the highest phenolic compound values. For flavonoids, the highest amount was obtained with the extraction using L‐proline and levulinic acid for the pitomba peel and ethanol and choline chloride with levulinic acid for the pitomba seeds. The results of the DPPH and FRAP assays indicate that, for antioxidant activity, the highest DPPH value was achieved with the extraction of pitomba peel using choline chloride with glycerol. In contrast, for pitomba seeds, elevated values were found with choline chloride with glycerol and choline chloride with levulinic acid. In the FRAP assay, the averages between L‐proline with levulinic acid and choline chloride with glycerol were not significantly different, showing high values. For pitomba seeds, the averages between ethanol and choline chloride with glycerol were also not significantly different and showed the highest obtained values. The results demonstrate that the extracts obtained from pitomba residues are rich in valuable compounds for potential applications in the food and pharmaceutical industries. They highlight the significant levels of flavonoids extracted from pitomba peel and seeds and emphasise the effectiveness of deep eutectic solvents (DES), particularly choline chloride with glycerol, in the extraction process.

A green recyclable process for selective recovery of Li and Fe from spent lithium iron phosphate batteries by synergistic effect of deep eutectic solvent and oxygen

This work designs a new method for recovering spent LiFePO4 cathode materials, aiming to address issues with traditional hydrometallurgy processes such as complex operations, low lithium recovery rates, and high wastewater discharge. The method involves using a deep eutectic solvent (DES) composed of chloroacetic acid and ethanol, and oxygen as an oxidant, for the cooperative leaching of LiFePO4 powders. Based on the acidic nature of the DES and the oxidizing properties of oxygen, LiFePO4 was undergone an in-situ transformation into solid FePO4, while 100% of lithium was dissolved in the DES with high selectivity. The FePO4 product can be recovered by filtration, and the addition of oxalic acid to the filtrate allows for lithium recovery. Importantly, the structure of the DES remained unchanged after use, allowing for three recycling cycles without a significant decrease in LiFePO4 recovery efficiency. This process is environmentally friendly, with no generation of acidic or alkaline wastewater, and boasts high metal recovery rates, showcasing its huge potential for application.

Synergistic Effect of Deep Eutectic Solvent and Zinc Oxide in Transesterification of Dimethyl Terephthalate for the Synthesis of Alkyl Terephthalate Esters

Synergistic Effect of Deep Eutectic Solvent and Zinc Oxide in Transesterification of Dimethyl Terephthalate for the Synthesis of Alkyl Terephthalate Esters

Effect of Deep Eutectic Solvents Based on Choline Chloride as Extractants on the Separation of the 1-Butanol–1-Butyl Formate System: Experimental Study and Comparative Analysis

Effect of Deep Eutectic Solvents Based on Choline Chloride as Extractants on the Separation of the 1-Butanol–1-Butyl Formate System: Experimental Study and Comparative Analysis

Balancing the pretreatment effect of deep eutectic solvents on biomass and the activity of β-glucosidase originating from Paenibacillus sp. LLZ1

The two major impediments to biomass resourcing are the catalytic efficiency of enzymes and the effectiveness of biomass pretreatment. In this study, six genes encoding β-Glucosidases (BGLs) derived from Paenibacillus sp. LLZ1 were cloned and expressed. The activity of BGL-F, which had the highest enzyme activity, was 24.1 U/mg, which was 39.8–83.7% higher than that of the other BGLs. Molecular docking and surface charge analyses showed that the binding energy of BGL-F to cellobiose and its electronegative ligand-binding pocket were greater than those of other BGLs. On the other hand, by calculating and comparing the Kamlet–Taft (KT) values of deep eutectic solvent (DES) composed of different hydrogen bond donors (HBD) and hydrogen bond acceptors (HDA), it was found that DES composed of betaine and glycerol had the highest α value of 0.97, meaning that it could provide the highest hydrogen bonding capacity, and thus it had the best pretreatment effect on biomass. Analysis by circular dichroism (CD) spectroscopy revealed a decrease in α-helix and an increase in β-strand in the secondary structure of the DES-treated BGL-F, implying an increase in enzyme activity and stability. This result was also confirmed experimentally by the fact that the Km and Vmax of the enzyme in the DES system increased by 13.2% and 57.9%, respectively, and the inactivation rate (kd) decreased by 21.4%. The results of this study showed that DES consisting of glycerol-betaine achieved a better balance between the promotion of enzyme activity and biomass pretreatment.

Comparative analysis of photo-fermentation hydrogen production from pretreated corn stover by deep eutectic solvents

To compare the pretreatment effect of deep eutectic solvents (DESs) on corn stover, three types of DESs (acid, neutral, and alkaline) were used to pretreat corn stover, and their effects on lignin removal were investigated. Then the performance of photo-fermentation hydrogen production (PFHP) using DESs pretreated corn stover was compared and analyzed. The results showed that acid DESs had the best lignin removal efficiency, and the lignin removal percentages of choline chloride/formic acid (ChCl/Fac) and choline chloride/oxalate (ChCl/Oac) were 64.7% and 65.6%, respectively. The alkaline DESs had the second highest removal of lignin, while the neutral DESs had a poor effect on lignin removal. The comparison of hydrogen production indicated that the corn stover pretreated with ChCl/Oac had the best hydrogen production effect. In conclusion, the DESs pretreatment can obviously remove the lignin in corn stover, and then improve the hydrogen production capacity and efficiency of photo-fermentation, which provides a potential pretreatment method for the efficient utilization of straw biomass.

Optimizing green approach to enhanced antioxidants from Thai pigmented rice bran using deep eutectic solvent-based ultrasonic-assisted extraction

Deep eutectic solvents (DES) have garnered significant attention as extraction media owing to their commendable attributes of being environmentally sustainable and the inherent adaptability of DES's versatile physical and chemical characteristics. The present study investigated the effects of deep eutectic solvents on the total contents of anthocyanin, phenolic, and flavonoids, as well as the antioxidant activity of Thai pigmented rice bran extract. The optimal extraction parameters for deep eutectic solvent-based ultrasonic-assisted extraction (DES-UAE) were also determined using the response surface methodology (RSM). The optimal conditions for the extraction of anthocyanins and other antioxidants from pigmented rice bran using a deep eutectic solvent were choline chloride: ethylene glycol (Ch:Eg) at a 1:2 ratio, mixed with 20 % water as a solvent. The ultrasonic-assisted extraction (UAE) at 37 kHz of frequency, 50 °C of temperature, 40 min of extraction time, and a 1:6 g/mL of solid-to-solvent ratio yielded a total anthocyanin content of 4.55 ± 0.09 mg C3G/g DW, a total phenolic content of 26.49 ± 0.62 mg GAE/g DW, a total flavonoid content of 6.57 ± 0.55 mg QE/g DW, and a percent inhibition of DPPH radical of 77.83 ± 1.51. By comparing the antioxidant content that was extracted from three cultivars of pigmented rice, it was found that Leum Pua black rice bran provided significantly higher antioxidant content compared to Hom Nin purple rice bran and Mali Dang red rice bran. This research suggests an achievable, eco-friendly, and effective method for preparing high-quality, consumer-safe Thai rice bran as a raw material for nutraceuticals.

Effect of Deep Eutectic Solvents on the Activity and Stability of Cellulases and Pectinases

Effect of Deep Eutectic Solvents on the Activity and Stability of Cellulases and Pectinases

Extraction of Chitin from Giant Tiger Prawn (Penaeus monodon) Shrimp Shell Using Deep Eutectic Solvents and Citric Acid

Chitin, a natural biomass resource, has shown great promise for a wide range of applications because of its high bioactivity. This study evaluated the effectiveness of deep eutectic solvents (DESs) mixed with citric acid as a method for extracting chitin from the shells of giant tiger prawn shrimps (Penaeus monodon). The purity and physicochemical properties of the extracted chitin were compared with those obtained using the traditional chemical extraction method and commercial chitin. The results showed that the highest chitin purity (99.22%) was achieved when choline chloride-glycerol (ChCl–Gl) was used in a 1:2 molar ratio with a citric acid content of 5% w/v (CG2-5%). Additionally, the extracted chitin had a molecular weight of 3.75 × 105 Da and a crystallinity index of 81.34%, which was slightly higher than that of chitin extracted using the conventional method (3.24 × 105 Da and 73.59%). However, there was no significant difference between chitin extracted by CG2-5% and commercial chitin. This suggests that the structure of the biopolymer remained intact following the CG2-5% extraction process. The α-chitins in tiger prawn shrimp shells, as confirmed by Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray Diffraction Analysis (XRD), are analogous to commercial shrimp chitin. These results, achieved without employing potentially harmful chemicals, demonstrate that CG2-5% can efficiently enhance chitin extraction from diverse raw biomass sources without jeopardizing the polymer's structural stability.

Effect of deep eutectic solvents on vulcanization and rheological behaviors of rubber vulcanizates

Deep eutectic solvents (DESs) are able to promote vulcanization of rubbers while the mechanisms remain unclear. Herein 4-methyl-5,7-dihydroxycoumarin (DHMC) as hydrogen bond donor (HBD) was used to synthesize DES by reaction with tetrabutylammonium bromide (TBAB) as hydrogen bond acceptor (HBA). The effects of DHMC, TBAB and DES on vulcanization of natural rubber (NR) and isoprene rubber (IR) were studied. It is shown that DES could participate in crosslinking network and adjust crosslinking density (vc) of the vulcanizates through physical and chemical interactions with NR non-rubber components, zinc oxide (ZnO) activator and N-cyclohexyl-2-benzothiazolesulfenamide (CZ) accelerator. Furthermore, DES influences linear and nonlinear rheological responses and mechanical behaviors of NR vulcanizates. The NR vulcanizates cured at 120 °C with 0.1–0.3 phr (part per hundred parts of rubber) DES exhibit higher tensile strengths and lower vc in comparison with the control one cured at 140 °C, which is assigned to the more homogenous crosslinking network in the former. This work provides an effective way to modulate the crosslinking network to produce high-strength vulcanizates at lowered vulcanization temperatures and ZnO amount, which is beneficial for the preparation of rubber products with high strengths and low hysteresis energies.

Effects of deep eutectic solvents on the activity and stability of enzymes

From introduction of deep eutectic solvents (DESs) in 2003 and because of their unique properties such as low melting points, safety, low cost of raw material, availability, sustainability, and biodegradability, DESs are garnering attention in various fields of technology, particularly biocatalysis. Progress in these fields has illustrated that enzymes are able to maintain and even improve their activity and stability in DES-based media. Consequently, they became promising alternatives as developed solvents, cosolvents, or additives over conventional organic solvents. The current study reviewed the recent progress of the effects of various DESs on the function and stability of different enzymes.

Effectiveness of deep eutectic solvents for light oil recovery through spontaneous imbibition

With the rise in demand for energy, comes the need to extract oil from not only primary and secondary stages, but also from tertiary recovery methods to keep up with the current market. Enhanced oil recovery (EOR) has become more prevalent within maturing reservoirs. Ionic liquids (IL) were highly regarded for chemical EOR until researchers raised concerns about their expensive cost, toxicity, and environmental impacts. Recently, deep eutectic solvents (DES) were discovered as a potential replacement for ILs due to their non-toxic nature, being biodegradable, non-flammable, and cheaper. In this study, the effectiveness of DES is investigated by observing its ability to promote oil recovery through wettability alteration. Spontaneous Imbibition tests along with emulsion and thermogravimetric tests (TGA) are used to achieve the objectives. Results indicated that both DESs can recover oil that was not recoverable using brine only. At higher temperatures, the effectiveness of DES was higher, which allowed for more oil to be imbibed out. The effect of concentration suggested that at high concentrations, DESs exhibit self-destructive properties by increasing interfacial tension (IFT), which reduced the imbibition rate and recovery factor. TGA studies indicate that the thermal stability of DESs is highly dependent on the thermal stability of their hydrogen bond donor (HBD).

Effects of deep eutectic solvents on the biotransformation efficiency of ω-transaminase

ω-transaminase (ω-TA) shows a significant promising in the synthesis of chiral amines. However, the poor activity of ω-TA in buffer water solution limits its application in industry, so green and economic methods adopted to improve ω-TA activity still face challenges. Here, deep eutectic solvents (DES) were used as the co-solvent to improve the catalytic activity of ω-TA. The results have shown that DES (ChCl: Urea 1:1) was the most suitable co-solvent for increasing the biotransformation efficiency of the ω-TA in nine different choline chloride-based DESs. The optimal enzymatic activity was achieved at 40 ℃, in 10 vol% DES and pH 8. The specific activity of ω-TA in DES was increased by 3.9 times due to the reinforced interactions between DES and enzyme. The kinetic analysis of transaminase showed that DES enhanced affinity of ω-TA for 1-(R)-PEA and pyruvate to increase by 1.93 and 1.63 times respectively compared with the control. Molecular docking shows that urea acted as a proton donor and a receptor during the enzymatic reaction, the docking binding energy increases to 3.21 and 3.59 kcal/mol, promoting the transamination reaction. DES can significantly improve the catalytic activity of ω-TA, which has broad development prospects in the field of green and efficient synthesis of pharmaceutical and natural product intermediates.

Acidic deep eutectic solvent assisted mechanochemical delignification of lignocellulosic biomass at room temperature

Lignocellulosic biomass is the most abundant natural polymer on Earth, but the efficient fractionation and refinery of all its components remain challenging. Acidic deep eutectic solvents refining is a promising method, while it is likely to cause lignin condensation and carbohydrates degradation, especially at server operation conditions. Here we propose the use of acidic deep eutectic solvent (DES), choline chloride/p-toluenesulfonic acid assisted mechanochemical pretreatment (DM) for efficient lignocellulose fractionation at mild condition. Four representative lignocellulose, wheat straw, moso bamboo, poplar wood and pine wood were selected at varied milling time (3, 6 h) to assess the fractionation ability of this strategy. This DM pretreatment demonstrated a rather high cellulose retentions (∼90 %) and extent of delignification for wheat straw and bamboo biomass, which corresponds to a high extent of enzymatic hydrolysis (∼75.5 %) for sugar platform pursuing. The extracted lignin showed rather high content of β-O-4′ leakages due to the swelling effect of deep eutectic solvent and mild operation conditions. This work provided a promising strategy to fractionate lignocellulose using deep eutectic solvents with the goal of simultaneous cellulose hydrolysis and reactive lignin obtaining that is usually difficult to realize using traditional chemical fractionation approach.

Combined Effects of Deep Eutectic Solvents and Pulsed Electric Field Improve Polyphenol-Rich Extracts from Apricot Kernel Biomass

Apricots are one of the most important fruits in the Mediterranean region for both their nutritional and economic value. They are widely cultivated and consumed fresh or dried or are used in the food industry for the production of jams, juices, etc. In any case, the seeds they contain constitute waste. The kernels are very rich in bioactive compounds such as polyphenols, a fact that makes them very appealing in cosmetology. However, the extraction of the bioactive compounds of apricot kernels is poorly examined. In this study, the preparation of polyphenol-rich extracts from apricot kernel biomass is discussed. To this end, a common extraction procedure with water as a solvent was employed. To enhance the extraction yield, the use of a deep eutectic solvent (DES) was examined. In addition, the use of pulsed electric field (PEF) either as a standalone extraction method or as a complementary step was also examined. According to the results, it was evident that when PEF was applied before the extraction procedure, an increase of 88% in the total polyphenol content (TPC) was recorded. Likewise, the use of a glycerol:choline chloride (2:1, w/w) DES increased the TPC by ~70%. When the two approaches were combined, a 173% increase was recorded. According to the above, it can be concluded that apricot kernel biomass is a very good source of polyphenols, especially using the proposed extraction procedure.

Enhancing effect of choline chloride-based deep eutectic solvents with polyols on the aqueous solubility of curcumin–insight from experiment and theoretical calculation

The development of green solvents for enhancing aqueous solubility of drug curcumin remains a challenge. This study explores the enhancing effect of deep eutectic solvents (DESs) on the aqueous solubility of curcumin (CUR) via experiment and theoretical calculation. Choline chloride-based DESs with polyols 1,2-propanediol (1,2-PDO), 1,3-propanediol, ethylene glycol, and glycerol as hydrogen bond donors were prepared and used as co-solvents. The CUR aqueous solubility increased with increasing the DESs content at temperature of 303.15–318.15 K, especially in aqueous ChCl/1,2-PDO (mole ratio 1:4) solutions. The positive apparent molar volume values and reduced density gradient analysis confirmed the existence of strong interactions between CUR and solvent. The van der Waals interactions and hydrogen bonding coexisted in DESs monomer retained the stability of DESs structure after introducing CUR. Moreover, the lower interaction energy of DESs⋅⋅⋅CUR system than that of the counterpart DESs further proved the strong interaction between CUR and DESs. The lowest interaction energy of ChCl/1,2-PDO⋅⋅⋅CUR system indicated that this system was the most stable and ChCl/1,2-PDO was promising for CUR dissolution. This work provides efficient solvents for utilizing curcumin, contributing to a deep insight into the interactions between DES and CUR at the molecular level, and the role of DESs on enhancing drugs solubility.

Liquid-liquid equilibrium experiment and mechanism analysis of menthol-based deep eutectic solvents extraction for separation of fuel additive tert-butanol

Deep eutectic solvents (DESs) were synthesized using menthol as hydrogen bond acceptor (HBA) and different carbon chain carboxylic acids as hydrogen bond donors (HBD). The liquid equilibrium (LLE) experiment was used to determine the distribution coefficient (β) and slectivity (S) at standard atmospheric pressure and temperature. The effect of DESs on the separation efficiency was discussed by changing the proportion. Non-random two fluid (NRTL) model was used to correlate the experimental data. The molecular dynamics (MD) simulation method was used to investigate the micro mechanism of the extraction process. The results show van der Waals force plays a leading role in the interaction between solvents and tert-butyl alcohol (TBA) and week force with water. Compared with experimental and simulation results, the interaction between DESs and TBA would also be affected by the change of the number of HBD carbon chains, and DESs with decanoic acid as HBD has the best separation effect, which verifies the feasibility of separating high alcohol compounds from water by DESs and then treating them by DESs.

Effect of deep eutectic solvents on the biocatalytic properties of β-glucosidase@ZnOFe nano-biocatalyst

In this work, we investigate the use of aqueous deep eutectic solvents (DESs) consisting of different hydrogen bond acceptors (choline chloride, ammonium salts or betaine) and hydrogen bond donors (amines, sugars and alcohols), as co-solvents in biocatalytic reactions catalyzed by a nano-biocatalyst with β-glucosidase (BGL) activity. For this purpose, β-glucosidase from Thermotoga maritima was immobilized on the surface of green zinc oxide-iron oxide nanoparticles (BGL@ZnOFe) derived from an aqueous olive leaf extract. The covalent bonding of β-glucosidase on the surface of nanoparticles was demonstrated by X-ray photoelectron spectroscopy. The effect of a wide range of DES solutions on the biocatalytic features of BGL@ZnOFe was thoroughly investigated. The concentration of DES as well as the specific combination of hydrogen bond acceptors and hydrogen bond donors had a significant impact on the hydrolytic activity of immobilized β-glucosidase. Most choline chloride and betaine-based DESs enhanced the enzymatic activity and thermal stability of BGL@ZnOFe up to 50%. The enzymatic activity of the nano-biocatalyst towards the hydrolysis of bioactive phenolic compounds depends on the nature of the DES used. Choline chloride:butylene glycol-based medium had beneficial effect on a transglycosylation reaction, such as the synthesis of salidroside, increasing the total turnover number of the biocatalytic process by 55%. This work indicates that the use of several choline chloride and betaine-based DESs can be successfully employed as green co-solvents in various hydrolytic and synthetic biocatalytic processes.