Deep Eutectic Solvent System Research Articles

Green and rapid oxidation of aldehydes using a catalytic applications of Deep Eutectic Solvent

The development of novel and environmentally friendly solvents for chemical reactions is a vital in the pursuit of sustainable chemistry. This study presents a sustainable and efficient protocol for the rapid oxidation of benzaldehyde derivatives in the presence of catalytic Deep Eutectic Solvent (DES) system to their corresponding benzoic acids. A novel ternary DES composed of Urea/ZnCl2/HCl was synthesized using a combination of Urea, ZnCl2, and HCl for the first time and employed as an environmentally friendly oxidation catalyst using H2O2 as an oxidant at 60 °C. Benzaldehyde derivatives with diverse range of functional groups and substitution patterns afforded remarkable results, as it achieved high to excellent yields of the corresponding benzoic acids within a remarkably short reaction time of only 50 min. This protocol offers several advantages over alternative methods, including high product yields, the elimination of toxic and hazardous solvents and catalysts, and straightforward experimental procedures. Furthermore, the synthesized DES excellent recyclability, allowing for its reuse up to five times without any significant loss of functionality. Moreover, the synthesized DES demonstrated exceptional recyclability, enabling it to be reused up to five times without experiencing any notable decline in its effectiveness or functionality.

Upcycling waste polymer membranes through eco-friendly solvent-catalysed valorisation for energy and environmental solutions

A facile pathway of upcycling waste/discarded polysulfone (WPSF) membranes has been proposed using deep eutectic solvent (DES) system composed of choline chloride and ethylene glycol (CC:EG) in 1:1 ratio as a green template. This approach offers a viable solution for addressing polymer membrane waste management challenges while simultaneously promoting feasible method, resource efficiency and economic viability. The WPSF was doped with Mn ions prior to the solvothermal conversion at 200 °C and pyrolysis at 900 °C. The obtained functional porous carbon showed superior adsorption capacity towards Malachite green (MG) (423.72 mg/g), Eriochrome black-T (EBT) (326.79 mg/g), Diclofenac (DCF) (195.31 mg/g), and Ofloxacin (OFX) (121.8 mg/g). The adsorption followed pseudo second order kinetics and well agreed with Langmuir isotherm. Further, the optimised carbon material i.e., Mn-WPSF-01 was used as an adsorptive-based membrane water filtration system, in which a remarkable water flux about 965 L.m−2.h−1 for different feed streams with outstanding rejection of >90% even after ten cycles of regeneration was obtained. Therefore, Mn-doped carbon materials integrate the advantages of easy preparation, robustness, and effective adsorption performances, as well as good recyclability. Furthermore, the utilized or secondary carbon materials were used as electrode system in supercapacitors after the pyrolysis, where they displayed a specific capacitance of 110.88 F/g at 0.1 A/g of current density with capacity retention 90.85% for about 20,000 cycles with a current density increased to 5 A/g. Therefore, this approach promises to recycle the WPSF via potential applications in water treatment and energy applications through greener way.

Decarboxylation of Hydroxybenzoic Acids to Phenol Via Deep Eutectic Solvents.

The development of greener and more sustainable synthesis processes for manufacturing commodity chemicals is of great importance. The majority of current phenol production methods involve harsh reaction conditions with high energy consumption, causing severe environmental pollution. In this study, we present a novel approach for the decarboxylation of hydroxybenzoic acids (HBAs) to phenol using a choline chloride-urea (ChCl-urea) deep eutectic solvent (DES). Our study reveals the remarkable dual performance of ChCl-urea both as a catalyst and solvent for the decarboxylation of HBA, resulting in a high phenol yield (94 mol %) under mild reaction conditions. The proposed reaction pathway, established through a combination of experiments and computational simulations, enhances our understanding of this process. The recyclability of the DES system during decarboxylation was also assessed. Our findings demonstrate that the integration of DES into conventional chemical processes can pave the way for sustainable manufacturing, exemplifying a novel approach for producing phenol from abundant natural resources using designer solvents.

Gelatin-strengthened elastomer derived from polymerizable deep eutectic solvent for soft ionotronics

It is widely recognized that resolving the trade-off between mechanical toughness and recyclability in elastomers presents a significant challenge. This study introduces a novel gelatin-strengthened, supramolecular cross-linked elastomer (PCCA-G) synthesized through in situ photo-polymerization of a polymerizable deep eutectic solvent (PDES) system composed of choline chloride and acrylic acid. The research highlights the dual benefits of integrating gelatin into the PDES system in the absence of covalent cross-linker, notably enhancing mechanical properties and recycle ability. The PCCA-G3 % elastomers demonstrate exceptional transparency with a transmittance of 95.4 %, robust mechanical strength (approximately 4.99 MPa), and substantial strain capacity (1169 %). These properties make the elastomers ideal for loading-bearing sensor applications, capable of monitoring various human motions with high accuracy and sensitivity. Furthermore, the elastomers exhibit outstanding recycle properties via a simple solvation-evaporation process, maintaining performance after multiple cycles. This work addresses the critical need for environmental-friendly materials potentially reducing the ecological impact of widespread sensor usage. The adaptable nature of these materials also positions them as promising candidates for future developments in sensor technology and soft ionotronics.

Antibacterial and antioxidant activities of Chlorella vulgaris and Scenedesmus incrassatulus using natural deep eutectic solvent under microwave assisted by ultrasound

Microalgae are increasingly recognized as promising sources of natural bioactive compounds. However, traditional extraction methods using volatile organic solvents (VOCs) pose environmental risks. This study explores renewable deep eutectic solvents (DES) as sustainable alternatives for extracting bioactive compounds from microalgae biomass, focusing on Chlorella vulgaris and Scenedesmus incrassatulus. Four DES systems, comprising choline chloride (ChCl) and glycerol, citric acid, urea, and glucose, were compared with three conventional solvents (ethanol, methanol, and water). Extraction efficiency was assessed based on total phenolic content (TPC), flavonoid content, and tannin content, followed by antioxidant activity evaluation using DPPH, CAT, and FRAP assays. Additionally, antibacterial activity of the DES extracts was determined against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 29213), and Bacillus subtilis (ATCC 3366) using disc diffusion and microplate dilution methods to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results reveal that DES, particularly choline chloride: citric acid, outperform conventional solvents in terms of polyphenol extraction efficiency, antioxidant activity, and antibacterial activity against both Gram-negative and Gram-positive bacteria. For instance, the citric acid-based DES (SIDES2) showed a TPC of 4.98 mg/g, while the conventional solvent ethanol exhibited a TPC of 3.27 mg/g. Additionally, SIDES2 exhibiting the highest DPPH scavenging activity of 75 %, compared to 60 % for ethanol. Furthermore, SIDES2 showed an MIC of 0.5 mg/ml against Staphylococcus aureus. This study underscores the potential of DES for sustainable extraction of natural antioxidants from microalgae biomass, contributing to the development of environmentally friendly extraction processes in various industries.

Deep eutectic solvents as sustainable and extraordinary all-in-one systems for oxidative desulfurization

Deep oxidative desulfurization (ODS) using deep eutectic solvents (DESs) was a promising and environmentally friendly technique. Herein, we report an innovative and straightforward approach for achieving efficient oxidative desulfurization using DESs. These DESs serve as all-in-one systems, encompassing catalysts, oxidants, and solvents. The results demonstrate the excellent desulfurization performance of a DES derived from meta-chloroperoxybenzoic acid (mCPBA) and dimethylethanolamine (DMAE) for the removal of dibenzothiophene (DBT) from model oil. The use of multi-component DES systems enhances efficiency and reduces toxicity compared to individual solvent components, resulting in deep desulfurization levels. The influence of crucial extraction parameters, such as extraction time, temperature, and amount of DES, was investigated. The results demonstrated that the mCPBA/DMAE-based DES exhibited the highest desulfurization efficiency, reaching up to 99 % under optimal conditions (60 °C, 90 min, and 1 mL of DES). Moreover, the exceptional stability and reusability of DESs were confirmed, as they maintained sustained desulfurization efficiency even after six cycles of reuse.

An Innovative Vortex-Assisted Liquid-Liquid Microextraction Approach Using Deep Eutectic Solvent: Application for the Spectrofluorometric Determination of Rhodamine B in Water, Food and Cosmetic Samples.

A new green and highly sensitive method for the determination of rhodamine B (RhB) by deep eutectic solvent-based vortex-assisted liquid-liquid microextraction with fluorescence detection (DES-VALLME-FLD) was developed. The extraction efficiency of conventional solvents and different deep eutectic solvent (DES) systems composed of tetrabutylammonium bromide (TBAB) and an alcohol (hexanol, octanol, or decanol) in different ratios were compared. DFT calculations of intermolecular electrostatic and non-covalent interactions of the most stable RhB forms with DES and water explain the experimental DESs' extraction efficiency. Semiempirical PM7 computations were used to obtain Hansen solubility parameters, which supported the good solubility of the monocationic RhB form in selected DESs. The dependence of the linear calibration of microextraction into 100 µL DES was observed in the RhB calibration range from 0.2 to 10.0 µg L-1 with a correlation coefficient of R2 = 0.9991. The LOD value was calculated to be 0.023 µg L-1. The accuracy and precision of the proposed method were verified over two days with RSD values of 2.9 to 4.1% and recovery of 94.6 to 103.7%. The developed method was applied to the determination of RhB in real samples (tap water, energy drink, and lipstick).

Applications of Functional Polymeric Eutectogels.

Over the past two decades, deep eutectic solvents (DESs) have captured significant attention as an emergent class of solvents that have unique properties and applications in differing fields of chemistry. One area where DES systems find utility is the design of polymeric gels, often referred to as "eutectogels," which can be prepared either using a DES to replace a traditional solvent, or where monomers form part of the DES themselves. Due to the extensive network of intramolecular interactions (e.g., hydrogen bonding) and ionic species that exist in DES systems, polymeric eutectogels often possess appealing material properties-high adhesive strength, tuneable viscosity, rapid polymerization kinetics, good conductivity, as well as high strength and flexibility. In addition, non-covalent crosslinking approaches are possible due to the inherent interactions that exist in these materials. This review considers several key applications of polymeric eutectogels, including organic electronics, wearable sensor technologies, 3D printing resins, adhesives, and a range of various biomedical applications. The design, synthesis, and properties of these eutectogels are discussed, in addition to the advantages of this synthetic approach in comparison to traditional gel design. Perspectives on the future directions of this field are also highlighted.

Machine-Learning-Assisted Design of Deep Eutectic Solvents Based on Uncovered Hydrogen Bond Patterns

Non-ionic deep eutectic solvents (DESs) are non-ionic designer solvents with various applications in catalysis, extraction, carbon capture, and pharmaceuticals. However, discovering new DES candidates is challenging due to a lack of efficient tools that accurately predict DES formation. The search for DES relies heavily on intuition or trial-and-error processes, leading to low success rates or missed opportunities. Recognizing that hydrogen bonds (HBs) play a central role in DES formation, we aim to identify HB features that distinguish DES from non-DES systems and use them to develop machine learning (ML) models to discover new DES systems. We first analyze the HB properties of 38 known DES and 111 known non-DES systems using their molecular dynamics (MD) simulation trajectories. The analysis reveals that DES systems have two unique features compared to non-DES systems: The DESs have ① more imbalance between the numbers of the two intra-component HBs and ② more and stronger inter-component HBs. Based on these results, we develop 30 ML models using ten algorithms and three types of HB-based descriptors. The model performance is first benchmarked using the average and minimal receiver operating characteristic (ROC)-area under the curve (AUC) values. We also analyze the importance of individual features in the models, and the results are consistent with the simulation-based statistical analysis. Finally, we validate the models using the experimental data of 34 systems. The extra trees forest model outperforms the other models in the validation, with an ROC-AUC of 0.88. Our work illustrates the importance of HBs in DES formation and shows the potential of ML in discovering new DESs.

A designed ZrOCl2/ethylene glycol deep eutectic solvent for efficient lignocellulose valorization

Deep eutectic solvents (DESs) hold great potential in biorefining because they can efficiently deconstruct the recalcitrant structure of lignocellulose. In particular, inorganic salts with Lewis acids have been proven to be effective at cleaving lignin–carbohydrate complexes. Herein, a Zr-based DES system composed of metal chloride hydrate (ZrOCl2·8H2O) and ethylene glycol (EG) was designed and used for poplar powder pretreatment. Zr4+-based salts provide sufficient acidity for lignocellulose depolymerization. The acidity of the DES was analysed by the Kamlet-Taft solvatochromic parameter, and the results demonstrated that the acidity can be regulated by the DES composition. Under the optimum conditions (ZrOCl2·8H2O:EG molar ratio of 1:2), the DES pretreatment removes nearly 100 % hemicellulose and 94.7 % lignin. The recovered lignin exhibited a low polydispersity of 1.7. The cellulose residues deliver an efficiency of 94.4 % upon enzymatic digestion. Moreover, the DES can be easily recovered with high yield and purity, and the recycled DES still maintains high delignification and enzymatic hydrolysis efficiencies. The proposed DES pretreatment technology is promising for biomass valorization.

Efficient lignin extraction from oil palm empty fruit bunches using guanidine-based deep eutectic solvents under microwave assistance

The abundance of oil palm empty fruit bunches (OPEFB) in Malaysia necessitates effective waste management strategies. Deep eutectic solvents (DES), particularly chloride-based ones like guanidine hydrochloride (GHCl), offer green and economical pretreatment options for lignocellulosic biomass, enhancing lignin extraction. To the best of current knowledge, no prior investigations have focused on the properties of lignin extracted using this DES system. Therefore, this study investigates the efficient extraction of lignin from oil palm empty fruit bunches (OPEFB) utilizing guanidine-based deep eutectic solvents (GHDES) under microwave assistance. Guanidine hydrochloride (GHCl) is introduced as a hydrogen bond acceptor (HBA) in DES formation, particularly in the GHCl:lactic acid (LA) system. The study systematically investigates the influence of different pretreatment parameters (time and temperature) on the structure and properties of the extracted lignin. Remarkably, guanidine-based DES shows exceptional effectiveness in disrupting the OPEFB structure, resulting in highly efficient lignin extraction. Analyzes show that the DES-extracted lignin has comparable properties to other DES systems, with consistent structural and thermal properties observed at various reaction temperatures and times. Notably, the extracted lignin at 120 °C for 30 min exhibited high yield, minimal impurity content, significant phenolic content, and reduced weight loss. This study not only contributes to the sustainable use of lignin but also highlights the versatility of guanidine-based DES in the utilization of lignocellulosic biomass. The promising results position guanidine-based DES as a viable and innovative candidate for lignin extraction in various applications and promote progress in the utilization of renewable biomass resources.

Explore the molecular mechanism of hydrogen bond regulation in deep eutectic solvents and co-amorphous phase transitions

Hydrogen bonding is an important intermolecular force that plays a crucial regulatory role in the phase transition of substances. Although it has been thermodynamically demonstrated that the solid-state form at room temperature is determined by the change in Tg depending on the mixing ratio. However, the molecular mechanisms of hydrogen bonding influencing the deep eutectic solvents (DES) and co-amorphous phase transition processes are still unclear. Therefore, in this study, miconazole nitrate (MN)-oxymatrine (OMT) DES (1:3) was prepared, along with the co-amorphous MN-OMT (2:1), to reveal the interaction mechanism of hydrogen bonding in the “liquid-solid” phase transition process. Firstly, the MN-OMT DES (1:3) and co-amorphous MN-OMT (2:1) were prepared by the solvent method. Secondly, FT-IR and NMR were used to study the interaction between MN-OMT DES (1:3), as well as the interaction between co-amorphous MN-OMT (2:1). The molecular mechanisms of DES and co-amorphous phase transition were explored through MD simulation and DFT computation. In addition, the essence of co-amorphous and DES formation was revealed through derivations based on the Henderson-Hasselbalch and Van’t Hoff equations, and the results of quantum calculations were verified. In summary, this study successfully prepared MN-OMT DES (1:3), as well as co-amorphous MN-OMT (2:1), and evaluated the molecular mechanisms of their phase transitions, which are of great significance for understanding the principles and regularities of DES and co-amorphous phase transition. This provides theoretical guidance for the development and application of novel DES and co-amorphous drug delivery systems.

Efficient base- and ligand-free palladium catalysed O-arylation of phenols in choline chloride:triethanolamine as a reusable deep eutectic solvent.

In this paper, we present a novel and sustainable approach using choline chloride:triethanolamine as a green, efficient and reusable deep eutectic solvent (DES) for Pd-catalysed O-arylation reactions with Pd/BaSO4 (10%). By using the unique properties of DESs, we successfully achieved C-O bond formation without the need for additional solvents, bases and ligands. This solvent/catalyst system ([ChCl][TEA]2) functioned as a dual catalyst and solvent system, enabling fast and environmentally friendly C-O bond formation from phenol derivatives and electron-deficient aryl halides, leading to remarkable yields under mild reaction conditions. To identify and characterize this DES, we employed differential scanning calorimetry, thermogravimetric analysis, Fourier-transform infrared spectroscopy, refractive index, viscosity, the potential of hydrogen (pH) and conductivity measurements. One of the remarkable advantages of this DES system is its exceptional stability. This solvent/catalyst system exhibited high stability throughout the reaction cycles, showing no significant loss of activity. As a result, this DES and catalyst (Pd/BaSO4 (10%)) can be easily recycled and re-used for up to three consecutive cycles, making it an economically and environmentally attractive option for organic reactions. Our approach offers several key benefits, including simple catalyst preparation, quick reaction times and excellent production efficiency.

Purification and components identification of ‘Ziyan’ anthocyanins

The new tea cultivar ‘Ziyan’ has high anthocyanin content. To explore its potential, the anthocyanin components were separated and prepared using the purple leaves of ‘Ziyan’ as raw materials. A deep eutectic solvent system was prepared for efficient extraction, replacing traditional solvents and achieving higher anthocyanin yield. The extraction parameters were optimized using response surface test and the yield of ‘Ziyan’ anthocyanin reached 5.06 ± 0.04 mg/g (dry weight) at a temperature of 65 °C, solvent moisture content of 29 %, solid-liquid ratio of 1:25 mg/mL and time of 39 min. The DM301 resin was preferred to recover anthocyanins from deep eutectic solvents, resulting in anthocyanin powder with a purity of 6.02 % and a color value of 29.1. It means ‘Ziyan’ anthocyanin has the potential to be developed as a food colorant. The enriched anthocyanins were analyzed using High Performance Liquid Chromatography-Diode Array Detection-Electrospray Tandem-Mass Spectrometry (HPLC-DAD-ESI-MS/MS), identifying 16 anthocyanin derivatives, including 5 acylated components. Petunidin and malvidin were found for the first time in ‘Ziyan’ tea cultivar. This study provided an important basis for the development of ‘Ziyan’ anthocyanins as a natural food and nutraceutical pigment.

In situ pretreatment of wood samples with deep eutectic solvents for enhanced lignin removal and enzymatic Saccharification efficiency optimization

Deep eutectic solvents (DESs) are commonly utilized as an effective pretreatment method for biomass materials, particularly for enhancing the value of lignocellulosic biomass. However, to the best of our knowledge, the utilization of DESs for in situ pretreatment of wood samples has been seldom reported. In this study, the ability of five DESs systems to in-situ pretreatment of balsa wood samples was investigated. Among of them, the Choline Chloride-Ethylene Glycol-P-Toluenesulfonic Acid (ChCl-EG-PTSA) system showing an excellent lignin removal rate (the lignin removal of 87.34 % and cellulose retention of 86.32 %), which is significantly better than the delignification effect of the traditional acid chlorite method (lignin removal of 72,13 % and cellulose retention of 64.57 %). In addition, in the subsequent enzymatic saccharification experiments, after the wood samples were pretreated in situ by the ChCl-EG-PTSA system, the enzymatic saccharification yield of cellulose reached 75.46 %, and the enzymatic saccharification yield of xylose reached 92 %. At the same time, this study also used SEM, FTIR, XPS, TGA and other testing technologies to conduct detailed analysis and characterization of the pretreated samples. This comprehensive analysis unequivocally demonstrated the viability of the ChCl-EG-PTSA system as an environmentally sustainable and efficient approach for pretreating forest biomass. Significantly, this in-situ wood pretreatment strategy significantly lays a robust research groundwork for the development of multifunctional wood fiber composites in subsequent stages.

Preparation and impregnation of deep eutectic solvents containing zileuton onto adsorbents to elicit the biopharmaceutical attributes

Deep eutectic solvent (DES) is a contemporary and eco-friendly solvent recently exploited to modulate the solubility of drugs. Herein, we developed DESs for an increment of solubility and bioavailability of zileuton (ZLT). ZLT is an anti-inflammatory drug categorized as an inhibitor of the enzyme 5-lipoxygenase commonly prescribed for treating chronic bronchial asthma. However, its therapeutic uses are limited owing to its poor water solubility. Several stable DESs were developed and assessed for viscosity, pH, and solubility. The DES comprising ChCl: EG (1:3) exhibits an excellent ZLT solubility (57.27 ± 0.14 mg/mL). The molecular and electrostatic interaction was assessed through a conductor-like screening model for real solvents (COSMO-RS). Further, 1H NMR analysis, FTIR, and digital microscopy were used to investigate the molecular transition in the chosen DES-ZLT. The DES in a liquid state possesses several drawbacks, such as instability, volatility, and dose precision. Therefore, a wet impregnation approach utilizing inert carriers such as Aerosil-200 and Avicel PH-102 was performed for the solidification of liquid DES. The solidified DES-ZLT was characterized by DSC and PXRD techniques and indicated the existence of ZLT in a highly dissolved state. Furthermore, solid DES-ZLT showed a significant increment in the dissolution studies, resulting in a 2.91 fold rise in oral bioavailability of ZLT. Hence, the presented study proves a well-organized and proficient development of a solid DES system to ameliorate the solubility and stability aspects of ZLT, which could provide the template for promising drugs that lack therapeutic effectiveness owing to solubility issues.

Experimental and Machine-Learning-Assisted Design of Pharmaceutically Acceptable Deep Eutectic Solvents for the Solubility Improvement of Non-Selective COX Inhibitors Ibuprofen and Ketoprofen.

Deep eutectic solvents (DESs) are commonly used in pharmaceutical applications as excellent solubilizers of active substances. This study investigated the tuning of ibuprofen and ketoprofen solubility utilizing DESs containing choline chloride or betaine as hydrogen bond acceptors and various polyols (ethylene glycol, diethylene glycol, triethylene glycol, glycerol, 1,2-propanediol, 1,3-butanediol) as hydrogen bond donors. Experimental solubility data were collected for all DES systems. A machine learning model was developed using COSMO-RS molecular descriptors to predict solubility. All studied DESs exhibited a cosolvency effect, increasing drug solubility at modest concentrations of water. The model accurately predicted solubility for ibuprofen, ketoprofen, and related analogs (flurbiprofen, felbinac, phenylacetic acid, diphenylacetic acid). A machine learning approach utilizing COSMO-RS descriptors enables the rational design and solubility prediction of DES formulations for improved pharmaceutical applications.

Asymmetric Additions Empowered by OrganoCatalysts, Metal Catalysts, and Deep Natural Eutectic Solvents (NADES).

This article is a history of an industrial-academic partnership that started almost two decades ago and details the evolution of a relationship between a small academic research group and a spin-out company located in Portugal. Their activities have ranged from the development of new metal-based catalytic systems for asymmetric epoxidations, allylic alkylations, and arylations to the development of novel cinchona-based organocatalysts for asymmetric hydrosilylations and Michael additions. Current common interests are centered on the development of novel chiral Natural Deep Eutectic Solvent systems, which they are investigating in different types of reaction systems.

Molecular dynamics simulations of choline chloride and ascorbic acid deep eutectic solvents: Investigation of structural and dynamics properties

Deep eutectic solvents (DESs) composed of choline chloride (ChCl) and ascorbic acid (AA) were investigated using the molecular dynamics (MD) simulations. The analyses of the configuration, radial distribution function (RDFs), coordination number, spatial distribution function (SDFs), interaction energies, hydrogen bond number, and self-diffusion coefficient of the ChCl/AA binary systems of different concentrations showed that the stability of the hydrogen bond network and the mutual attraction between systems were the strongest at the experimental eutectic concentration (molar ratio of 2:1). In our simulated temperature range from 303.15 to 353.15 K, the hydrogen bonding network of ChCl/AA DES does not undergo considerable alterations, indicating that its stability was insensitive to temperature. In addition, the influence of the water content on the ChCl/AA DES system was further investigated. The simulated results revealed that the water molecules could disrupt the formation of the hydrogen bonding network by occupyin positions that are essential for the formation of hydrogen bonds within the DES system.

Sustainable solutions of using deep eutectic solvents for hemp degumming: A combined experimental and DFT study

AbstractAiming at the problems of heavy environmental pollution, high energy consumption, and process complexity for current degumming techniques, three types of deep eutectic solvent (DES) systems as eco‐friendly sustainable solutions including choline chloride/urea (CU), ethylenediamine hydrochloride/ethylene glycol (EE) and choline chloride/imidazole (CI) were prepared and applied to the degumming of seed hemp. It was clearly showed that all three DES systems exhibit excellent degumming efficiency on seed hemp to remove noncellulosic components involving in pectin, hemicellulose, and lignin in amorphous region without damage to the structure and crystalline morphology of cellulose, leading to an increase of cellulose portion from 54% to about 80%. CI with the molar ratio of 3:8 at 175°C for 2.5 h give the best removal performance for hemicellulose and pectin while EE with molar ratio of 1:2 at 175°C for 3 h can remove lignin with highest efficiency. However, CU with the lowest cost reveals a balanced removal of three noncellulosic components, which may be the optimal choice for industrial production. Furthermore, density functional theory analysis disclosed the essential information of configuration stability for three DES systems.