Choline Chloride-based Deep Eutectic Solvents Research Articles

Production of 5-hydroxymethylfurfural from chitosan using choline chloride-based deep eutectic solvents as catalyst

This study explores an efficient catalytic system for the conversion of chitosan into 5-hydroxymethylfurfural (5-HMF) under hydrothermal conditions. The catalysts used are deep eutectic solvents (DESs) comprising choline chloride (ChCl) as the hydrogen bond acceptor (HBA) and various organic acids as the hydrogen bond donor (HBD). Among the DESs tested, the ChCl: oxalic acid (OA) combination exhibits the highest catalytic activity, resulting in a yield of 27.5% 5-HMF employed the optimized conditions. To elucidate the interaction between ChCl and OA, various analytical techniques were employed, including quantum chemical calculations, nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopy (FTIR). These investigations confirmed the formation of strong hydrogen-bonds between ChCl and OA. Furthermore, the solid residues obtained during the conversion process were characterized using FTIR, X-ray diffraction (XRD), and scanning electron microscopy (SEM). These analyses provide insights into the chemical structures and morphologies of the residues, revealing the gradual conversion of chitosan, along with the formation of humin by-products.

Life cycle assessment of tomato biomass residue anaerobic digestion preceded by ethanol-based organosolv and choline chloride-based deep eutectic solvent

Anaerobic digestion (AD) of lignocellulosic wastes (LW) has garnered substantial interest because of its notable energy and nutrient recovery, along with its potential for reducing greenhouse gas emissions. However, the LW is resistant to degradation, and its hydrolysis typically requires harsh conditions, hence the need for a pretreatment. Conducting a life cycle assessment (LCA) to evaluate the pretreatment of LW is an effective way to assess the environmental impacts associated with various pretreatment methods. This work evaluates and compares three scenarios for handling lignified tomato green waste (TGW), generated in the Greater of Agadir in Morocco, in terms of their environmental impacts and energy demand, using the LCA approach, performed with OpenLCA software. To achieve this aim, the impact of these scenarios on 11 indicators is studied. The analyzed management options include a base case scenario S0 where TGW undergoes a direct anaerobic digestion (AD), organosolv pretreatment of TGW followed by AD of the free-lignin fraction (S1), and choline chloride-based deep eutectic solvent (DES) delignification followed by AD of the free-lignin fraction (S2). The data used for the analysis comes from the Tamelast landfill, laboratory tests, literature, CML-IA baseline and Monte Carlo simulation calculations. The results obtained showed that the introduction of pretreatments in S1 and S2 mitigates significantly the environmental impact in different categories compared to S0. Scenario S2, with its enhanced recovery processes, shows the highest positive environmental contributions, despite its reliance on additional external electricity. S1 and S0 both respect energy circularity. Through this study, it has been demonstrated that chemical pretreatment of LW is energy, water and solvent-intensive and requires a large investment. It opens up perspectives for further works on pretreatment using natural DES technology, its development and its applications in the delignification of ligneous biomass on an industrial scale.

Efficient binary diol-based deep eutectic solvent pretreatment for enhancing enzymatic saccharification and lignin fractionation from eucalyptus

An innovative binary biol-based deep eutectic solvent (DES), specifically ethylamine hydrochloride-ethylene glycol (EaCl-EG), was developed for efficient pretreatment of eucalyptus biomass. This DES exhibited superior performance in achieving high delignification (85.0%) and xylan removal (80.0%), while preserving a significant amount of cellulose (94.5%) compared to choline chloride-based DES. Notably, the pretreated eucalyptus residues showed a remarkable glucose yield of over 92.5%, representing a substantial enhancement of up to 15 times compared to untreated eucalyptus. Furthermore, the pretreated liquor yielded high-purity lignin with a yield of 97.8%, characterized by well-preserved β-O-4 structure and nanoscale dimensions. These lignin nanoparticles (LNPs) were subsequently self-assembled into lignin nanobottles (LNBs), adding further value to the pretreatment process. The proposed novel binary EaCl-EG DES presented great potential as an efficient pretreatment solvent for future biomass fractionation processes.

Viscosity of deep eutectic solvents: Predictive modeling with experimental validation

Viscosity, the measure of a fluid's resistance to deformation, is a critical parameter in many industries. Being able to accurately predict viscosity is essential for the successful design and optimization of technological processes. In this research, regression models were created to predict the viscosity of deep eutectic solvents (DESs). Machine learning models were trained using a data set of 3440 data points for two component DESs. Different algorithms, such as Multiple Linear Regression, Random Forest, CatBoost, and Transformer CNF, were employed alongside a variety of structural representations like fingerprints, σ-profiles, and molecular descriptors. The effectiveness of the models was assessed for interpolation tasks within the training data and extrapolation outside of it. The results indicate that a rigorous splitting of the dataset into subsets is necessary to accurately evaluate the performance of the models. Two new choline chloride-based DESs were prepared and their viscosities were measured to evaluate the predictive capabilities of the models. The CatBoost algorithm with CDK molecular descriptors was chosen as the recommended model. The average absolute relative deviations (AARD) of this model exhibited fluctuations during 5-fold cross-validation, ranging from 10.8 % when interpolating within the dataset to 88 % when extrapolating to new mixture components. The open access model was presented in this study (http://chem-predictor.isc-ras.ru/ionic/des/).

Enhanced water absorption in pectin-chitosan hydrogel via modification with deep eutectic solvent: Optimisation and characterisation

Natural polymers are widely available, nontoxic, and biodegradable but have lower absorption when used to create hydrogels. Thus, a new modification of hydrogel combining pectin and chitosan was developed using choline chloride-based deep eutectic solvents (DESs) with ethylene glycol (DES1), glycerol (DES2), and acetic acid (DES3) called eutectogel. DES was added due to the hydrophilic site, which can increase water absorption. The eutectogel with each DES, including control (without DES), were optimized in their ratio of pectin to chitosan (0.5:1, 1:1, 1.5:1, and 2:1) and DES concentration (10 %, 20 %, and 30 %) to obtain the highest water absorption capacity (WAC). All developed gels showed the highest WAC at a ratio 0.5:1 of pectin to chitosan, with 20 % each of DES1, DES2, and DES3 labeled as E20, G20, and A20 having WAC values of 16.02, 13.50, and 12.50 g/g, respectively, owing to the existence of additional hydrophilic sites from DES within the gel for water binding. While the WAC value for the control was 6.2 g/g, this study proves the ability of DES to increase the WAC of E20, G20, and A20 more than two times compared to the control. E20 showed the highest water sorption because of the shorter and smaller size of ethylene glycol in DES1, with two less hindered hydroxyl groups efficiently binding with water molecules compared to glycerol and acetic acid. The interactions were observed through FTIR analysis, specifically in the amino groups of chitosan and carboxyl groups of pectin at the peak of 1636 to 1642 cm−1, which served as indicators of the electrostatic interaction with the modified DES and peak 3335 to 3350 cm−1 indicated of hydrogen bonding. The hydrogen bonding was also confirmed via DSC thermal analysis at 164.06°C to 188.44 °C. Characterization with FTIR, UV–Vis, and DSC confirmed the successful integration of DES, and it revealed that the new hydrogels had better transparency and thermal stability, with E20 showing the best overall performance in enhanced water absorption.

One-Pot Sequential Synthesis of Alkenylated Dihydroquinolinones and Hexahydroacridinones in Deep Eutectic Solvent Medium.

The sequential synthesis of N-heterocycles from saturated ketones poses significant challenges and has rarely been reported. Herein, an efficient synthesis of alkenylated dihydroquinolinones 7 and hexahydroacridinones 8 is achieved from saturated ketones 1 or 2 via dehydrogenation, cyclization, oxidation, and α-alkenylation in choline chloride-based deep eutectic solvent (DES) medium. This strategy provides alkenylated dihydroquinolinones 7 and hexahydroacridinones 8 in excellent yield from low-cost, readily available starting materials under environmentally benign conditions. Furthermore, the synthesized compounds (4, 5, 7, and 8) were investigated for their photophysical properties through absorption and emission spectral studies.

Green leaching and predictive model for copper recovery from waste smelting slag with choline chloride-based deep eutectic solvent

This research was performed to investigate the optimization of copper recovery from copper smelting slag (CSS) with a deep eutectic solvent as green reagent. The effect of important parameters on leaching efficiency of copper and zinc (as well as dissolution of iron), such as leaching time, leaching temperature, liquid/solid ratio, and particle size was studied. In order to model the copper recovery, an optimization method was used. According to the chemical analysis of CSS, the slag contains 0.9% copper, 3.3% zinc, and 36.7% iron. Also, it was found that the CSS is mainly composed of Fe2SiO4, Fe3O4, and SiO2. Copper-containing structures were determined as CuO and CuS. As a result of leaching experiments, 80% copper and 61% zinc recoveries were obtained at 48 h, 95 °C, 1/25 g·ml–1, and -33 μm. It is noted that the iron and silicon dissolution remained negligible under the selected conditions. According to the mathematical model, the highest copper leaching efficiency (up to 100%) could get under optimum working conditions as 48.5 °C leaching temperature, 40.1 hours leaching duration, and 62.3 ml·g–1 liquid/solid ratio. Also, the proposed model revealed that wide range of experimental levels can be used as leaching parameter to get desired metal leaching efficiency.

Green Approaches for the Extraction of Banana Peel Phenolics Using Deep Eutectic Solvents.

Banana peels, comprising about 35% of the fruit's weight, are often discarded, posing environmental and economic issues. This research focuses on recycling banana peel waste by optimizing advanced extraction techniques, specifically microwave-assisted (MAE) and ultrasound-assisted extraction (UAE), for the isolation of phenolic compounds. A choline chloride-based deep eutectic solvent (DES) with glycerol in a 1:3 ratio with a water content of 30% (w/w) was compared to 30% ethanol. Parameters, including sample-to-solvent ratio (SSR), extraction time, and temperature for MAE or amplitude for UAE, were varied. Extracts were analyzed for hydroxycinnamic acid (HCA) and flavonoid content, and antioxidant activity using FRAP and ABTS assays. DES outperformed ethanol, with HCA content ranging from 180.80 to 765.92 mg/100 g and flavonoid content from 96.70 to 531.08 mg/100 g, accompanied by higher antioxidant activity. Optimal MAE conditions with DES were an SSR of 1:50, a temperature of 60 °C, and a time of 10 min, whereas an SSR of 1:60, time of 5 min, and 75% amplitude were optimal for UAE. The polyphenolic profile of optimized extracts comprised 19 individual compounds belonging to the class of flavonols, flavan-3-ols, and phenolic acids. This study concluded that DESs, with their superior extraction efficiency and environmental benefits, are promising solvents for the extraction of high-value bioactive compounds from banana peels and offer significant potential for the food and pharmaceutical industries.

Recovery of Metals from the "Black Mass" of Waste Portable Li-Ion Batteries with Choline Chloride-Based Deep Eutectic Solvents and Bi-Functional Ionic Liquids by Solvent Extraction.

Lithium-ion portable batteries (LiPBs) contain valuable elements such as cobalt (Co), nickel (Ni), copper (Cu), lithium (Li) and manganese (Mn), which can be recovered through solid-liquid extraction using choline chloride-based Deep Eutectic Solvents (DESs) and bi-functional ionic liquids (ILs). This study was carried out to investigate the extraction of metals from solid powder, black mass (BM), obtained from LiPBs, with various solvents used: six choline chloride-based DESs in combination with organic acids: lactic acid (1:2, DES 1), malonic acid (1:1, DES 2), succinic acid (1:1, DES 3), glutaric acid (1:1, DES 4) and citric acid (1:1, DES 5 and 2:1, DES 6). Various additives, such as didecyldimethylammonium chloride (DDACl) surfactant, hydrogen peroxide (H2O2), trichloroisocyanuric acid (TCCA), sodium dichloroisocyanurate (NaDCC), pentapotassium bis(peroxymonosulphate) bis(sulphate) (PHM), (glycine + H2O2) or (glutaric acid + H2O2) were used. The best efficiency of metal extraction was obtained with the mixture of {DES 2 + 15 g of glycine + H2O2} in two-stage extraction at pH = 3, T = 333 K, 2 h. In order to obtain better extraction efficiency towards Co, Ni, Li and Mn (100%) and for Cu (75%), the addition of glycine was used. The obtained extraction results using choline chloride-based DESs were compared with those obtained with three bi-functional ILs: didecyldimethylammonium bis(2,4,4-trimethylpentyl) phosphinate, [N10,10,1,1][Cyanex272], didecyldimethylammonium bis(2-ethylhexyl) phosphate, [N10,10,1,1][D2EHPA], and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate, [P6,6,6,14][Cyanex272]/toluene. The results of the extraction of all metal ions with these bi-functional ILs were only at the level of 35-50 wt%. The content of metal ions in aqueous and stripped organic solutions was determined by ICP-OES. In this work, we propose an alternative and highly efficient concept for the extraction of valuable metals from BM of LiPBs using DESs and ILs at low temperatures instead of acid leaching at high temperatures.

Probing the interaction mechanism of choline chloride-based deep eutectic solvents with flavonoid and polyphenol systems

Choline chloride-based deep eutectic solvents (DES) have been demonstrated as promising green solvents for the extraction of flavonoids and polyphenols. This study investigates the interaction between six different hydrogen bond donors (HBD) choline chloride-based DES and three types of polyphenolic flavonoid substrates. Density functional theory (DFT) and molecular dynamics (MD) simulations suggest that Cl− dominates the interaction primarily through electrostatic forces. The extraction effect of alcohol DES on rutin was optimized obviously, and the maximum interaction could reach 737.6 kJ/mol. Acid DES has a better extraction effect on anthocyanins, with a maximum interaction of 376.4 kJ/mol. With the increase of the carbon chain of HBA and the increase of the number of functional groups, the interaction between DES and the active substance decreases. As HBD, ethanolamine with both hydroxyl and amino groups showed the best effect in the extraction process of DES, forming the maximum interaction energy of 1575.8 kJ/mol. Additionally, multivariate analysis is employed to establish the relationship between different variables and interaction energy. This study provides micro-theoretical support for the extraction of flavonoids and polyphenols.

Measurement and thermodynamic modelling of the solubilities of caffeic acid, p-coumaric acid and ferulic acid in three choline chloride-based deep eutectic solvents

This work presents experimental solubility measurements for three cinnamic acid derivatives (CADs) namely caffeic acid (CA), p-coumaric acid (p-CA) and ferulic acid (FA) in three Deep Eutectic Solvents (DESs), choline chloride-1,2 butanediol (ChCl:1,2 butanediol (1:4)), choline chloride-1,4 butanediol (ChCl:1,4 butanediol (1:4)) and choline chloride-acetic acid (ChCl:Acetic Acid (1:2)). All measurements were performed in the temperature range of 293.15 to 323.15 K and at atmospheric pressure. Density and viscosity measurements of pure DESs ChCl:1,2 butanediol (1:4) and ChCl:1,4 butanediol (1:4) are also reported. ChCl:1,4 butanediol (1:4) and ChCl:1,2 butanediol (1:4) reveals the highest solvation capacity for CADs among the examined solvents, while p-CA was found to be less soluble than CA and FA in all solvents. Thermodynamic functions of dissolution were also determined using the Van’t Hoff equation and the results imply that the process is endothermic for all systems studied. Finally, UNIQUAC and NRTL activity coefficient models were satisfactorily implemented to correlate the experimental solubilities.

Effects of hydrogen bond donors on PVDF membrane modification using choline chloride-based deep eutectic solvents

Deep eutectic solvents (DESs) were investigated as promising candidates in modifications towards hydrophobic polyvinylidene fluoride (PVDF) membranes based on its hydrophilic and hygroscopic properties. Five choline chloride-based DESs with various hydrogen bond donor (HBD) components were investigated as PVDF membrane modifiers by blending it with the membrane dope solution at 2 wt%. The incorporation of DESs appeared to influence the structure and morphology of the membranes, where macrovoid formations were suppressed and the formation of thin, densely porous skin layers were promoted as observed through SEM imaging. DES incorporation showed effects in contact angle reduction of the PVDF membranes from 90.22° to 60.07°, indicating hydrophilic modifications. Additionally, modifications with DESs yielded improvements in membrane flux (62.49 L/m2·h using glycerol-HBD) and protein solute rejection (74.62 % using glucose-HBD), though the overall tensile strength of the membranes were decreased from 4.24 MPa to the lowest value of 2.92 MPa. Ultimately, DESs were shown to be significant pore-forming agents in altering the morphology of PVDF membranes, and improving the thermal stability. Among the five tested DESs, PVDF modified with glycerol-HBD DES yielded the best membrane parameters and performances. DESs were demonstrated as prospective membrane modifiers in inducing hydrophilicity and influencing membrane morphology.

Experimental and Theoretical Insights into the Intermolecular Interactions in Saturated Systems of Dapsone in Conventional and Deep Eutectic Solvents.

Solubility is not only a crucial physicochemical property for laboratory practice but also provides valuable insight into the mechanism of saturated system organization, as a measure of the interplay between various intermolecular interactions. The importance of these data cannot be overstated, particularly when dealing with active pharmaceutical ingredients (APIs), such as dapsone. It is a commonly used anti-inflammatory and antimicrobial agent. However, its low solubility hampers its efficient applications. In this project, deep eutectic solvents (DESs) were used as solubilizing agents for dapsone as an alternative to traditional solvents. DESs were composed of choline chloride and one of six polyols. Additionally, water-DES mixtures were studied as a type of ternary solvents. The solubility of dapsone in these systems was determined spectrophotometrically. This study also analyzed the intermolecular interactions, not only in the studied eutectic systems, but also in a wide range of systems found in the literature, determined using the COSMO-RS framework. The intermolecular interactions were quantified as affinity values, which correspond to the Gibbs free energy of pair formation of dapsone molecules with constituents of regular solvents and choline chloride-based deep eutectic solvents. The patterns of solute-solute, solute-solvent, and solvent-solvent interactions that affect solubility were recognized using Orange data mining software (version 3.36.2). Finally, the computed affinity values were used to provide useful descriptors for machine learning purposes. The impact of intermolecular interactions on dapsone solubility in neat solvents, binary organic solvent mixtures, and deep eutectic solvents was analyzed and highlighted, underscoring the crucial role of dapsone self-association and providing valuable insights into complex solubility phenomena. Also the importance of solvent-solvent diversity was highlighted as a factor determining dapsone solubility. The Non-Linear Support Vector Regression (NuSVR) model, in conjunction with unique molecular descriptors, revealed exceptional predictive accuracy. Overall, this study underscores the potency of computed molecular characteristics and machine learning models in unraveling complex molecular interactions, thereby advancing our understanding of solubility phenomena within the scientific community.

Process design for acidic and alcohol based deep eutectic solvent pretreatment and high pressure homogenization of palm bunches for nanocellulose production

This research aimed to study on nanocellulose production from palm bunch using process design and cost analysis. Choline chloride based deep eutectic solvent pretreatment was selected for high-purity cellulose separation at mild condition, followed by nano-fibrillation using mechanical treatment. Three types of choline chloride-based deep eutectic solvents employing different hydrogen-bond donors (HBDs) namely lactic acid, 1,3-butanediol and oxalic acid were studied. The optimal cellulose extraction condition was choline chloride/lactic acid (ChLa80C) pretreatment of palm empty bunch at 80 °C followed by bleaching yielding 94.96%w/w cellulose content in product. Size reduction using ultrasonication and high-pressure homogenization produced nanocellulose at 67.12%w/w based on cellulose in raw material. Different morphologies of nanocellulose were tunable in the forms of nanocrystals, nano-rods and nanofibers by using dissimilar deep eutectic solvents. This work offered a sustainable and environmentally friendly process as well as provided analysis of DES pretreatment and overview operating cost for nanocellulose production. Application of nanocellulose for the fabrication of highly functional and biodegradable material for nanomedicine, electronic, optical, and micromechanical devices is achievable in the near future.

Molecular mechanism and extraction performance evaluation of choline chloride-based deep eutectic solvents for phenol separation from oil: Different glycols as hydrogen bond donors

Highly efficient separation of phenols from coal-to-liquids can enhance the economics of the coal conversion process. The selection of extractants with high extraction efficiency and low neutral oil entrainment is significant for energy development strategy. In this study, four ChCl-based DESs with different glycols as hydrogen bond donors (HBDs) were designed for the separation of phenol/toluene mixtures and the experimental results were analyzed by theoretical calculations. The experimental results showed that ChCl-EG had the highest extraction efficiency (94.02 %) and the least entrainment of toluene (0.449 g). Meanwhile, it could be regenerated and reused four times with no significant change in extraction capacity. The formation of hydrogen bonds between DESs and phenol was elucidated by σ-profile based on COSMO-SAC model. Multi-scale simulations and comparative analyses of the micro-mechanisms of the DESs system were carried out using quantum chemical (QC) and molecular dynamics (MD). It was shown that the attraction of DESs to phenol was mainly due to hydrogen bonds and vdW forces, with hydrogen bond interaction between Cl− in ChCl and H atom in phenol hydroxyl group being dominant. As the chain length of HBDs increased, the interaction of DESs with phenol was enhanced, while the entrainment of toluene also increased. Overall, the effect on the separation of phenol by different chain lengths of glycols as HBDs is elucidated. This study provides a theoretical reference for selecting and designing other DES extractants to separate phenol/toluene systems and similar systems.

Antioxidant and antidiabetic potential of Acanthus mollis L. using choline chloride-based deep eutectic solvents

In recent years, the study of medicinal plants’ therapeutic properties has increased due to their effects and biological activities. The Acanthaceae family consists of 242 genera and 3947 species mainly distributed across tropical and subtropical zones. This family is known to contain a wide range of bioactive compounds, such as, alkaloids, triterpenes steroids glycosides, polyphenols, and polysaccharides. Herein, the antioxidant and anti-diabetic effects of Acanthus mollis (AM) extracted by green alternative technology; ultrasound assisted-deep eutectic solvents extraction (UAE- DES) were determined. The data obtained, showed that AM seeds had the highest Total Phenolic Content, antioxidant activity and anti-diabetic activity compared to AM seeds shell. The presence of antioxidants with anti-diabetic proper- ties in AM could potentially serve as a foundation for innovative drug formulations capable of addressing several diseases. However, it is strongly advised that studies, including toxicity assessments, be conducted with a view to- wards pharmaceutical applications.

Eco-friendly Functionalization of MWCNTs with Deep Eutectic Solvents

The unique features of deep eutectic solvents (DESs) have sparked interest in their use for various applications due to their capacity to introduce new functional groups and other surface alterations. In this study, DESs were employed for the surface modification of MWCNTs. Twelve distinct varieties of Choline chloride-based DESs were prepared and characterized. Prior to the MWCNTs functionalization process, further tests, including viscosity, density, and TGA analysis, were carried out to evaluate the stability of the prepared solvents. The surface functionalization of MWCNTs was then carried out using the most stable solvent. The DESs-functionalized samples were tested for dispersibility and solubility, and FTIR was used to confirm the functional groups present. In comparison to the pristine MWCNTs, the result showed that samples D1, D2, and D4 had several functional groups on their surfaces. Also, in comparison to other DESs-functionalized samples, D1, D2, and D4 had more oxygen-containing groups, as further corroborated by CHNS analysis.As a result, DESs comprising glycerol and ethylene glycol provide an environmentally benign route to alter the surface of MWCNTs, making them suitable functional materials for a range of uses such as Adsorbents, Catalysts, Li batteries, EMI shielding materials, and Supercapacitor electrolytes.

Ultrasound-assisted oxidative desulphurization of coal using choline chloride-based deep eutectic solvents

Ultrasound-assisted oxidative desulphurization of coal using choline chloride-based deep eutectic solvents

Ultrasound assisted choline chloride-based deep eutectic solvent extraction of bioactive compounds from salsify (Tragopogon buphthalmoides (DC.) boiss. Var. Latifolius Boiss.): A Box–Behnken design approach for optimization

This study aimed to investigate the ultrasound-assisted extraction of bioactive compounds from salsify using deep eutectic solvents (DESs) with different molar ratios. For this reason, total phenolic (TPC), total flavonoid (TFC) compounds, and antioxidant activities (1,1-diphenyl-2-picrilhydrazyl radical scavenging activity (DPPH•), and ferric reducing antioxidant power (FRAP)) of extracts prepared with DES were investigated with an experimental design and optimization study conducted for this purpose. An extraction time of 40.15 min was determined as the optimal condition. Under these conditions, a molar ratio of 3:1 (acetic acid:choline chloride) and a water ratio of 42.17 % provided the highest phenolic/flavonoid compounds and antioxidant activity. Correlations between water ratio, molar ratio, and sonication extraction time were determined using principal component analysis (PCA). In conditions where TPC, FRAP, and DPPH• were high according to PCA, it can be concluded that the extraction time, water ratio, and molar ratio are at high levels; contrarily, TFC is at a low level. In conclusion, ultrasound-assisted extraction using DES proved effective for salsify. Therefore, choline chloride-based DESs, can be recommended as environmentally friendly green solvents and an alternative to organic solvents for the extraction of bioactive compounds from salsify.

Effectiveness of ammonium-based deep eutectic solvents in extracting polyphenol from Chlorella vulgaris

This study investigated the extraction of polyphenols from Chlorella vulgaris microalgae using environmentally friendly choline chloride-based deep eutectic solvents (DESs), specifically DES 1 (choline chloride: ethylene glycol, 1:2) and DES 2 (choline chloride: glycerol, 1:2). Thermal characterization of DESs through DSC analysis confirmed their formation as a glass former, while through density and viscosity analysis reveals their influence on extraction efficiency. Both DESs and methanol were employed in solid-liquid extraction combined with centrifugation. The Folin-Ciocalteu method quantified total phenolic content, showing DES 1 and DES 2 to outperform methanol (80.04, 68.63, and 60.15 mg GAE/g, respectively). High performance liquid chromatography (HPLC) was used in order to confirm these results. The HPLC result revealed that DES 1 exhibited the highest extraction efficiency at 198.00 ± 4.45 mg/L of Gallic acid yielded, followed by DES 2 at 189.83 ± 4.84 mg/L and the lowest is MeOH at 138.47 ± 5.36 mg/L. DPPH Radical Scavenging assay indicated both DES 1 and DES 2 extracts with significant radical scavenging activity (88.45 ± 0.17) % and (66.13 ± 1.62) %, respectively, compared to MeOH extracts that showed the lowest antioxidant activity at (30.41 ± 1.70) %. Overall, this study highlighted the potential of DESs in enchancing polyphenol extraction from Chlorella vulgaris, with room for further optimization and exploration of DES-polyphenol interactions.