Deep Eutectic Solvents Research Articles

Exploring the Efficiency of Caprylic Acid and Quaternary Ammonium Salt-Based Deep Eutectic Solvents for Separation of CO2 and H2S from Gas Mixtures Using Molecular Dynamics Simulations and COSMO-RS

In the present study, quaternary ammonium salts (QAS) and caprylic acid based deep eutectic solvents (DES) were employed for the separation of CO2 and H2S from natural gas (NG). To understand the extraction mechanisms of H2S from NG, we utilized MD simulations to understand intermolecular interactions between the gases and the eutectic solvents. Our detailed analysis for better understanding of QAS absorption capability in H2S extractions included combined distribution functions (CDFs), which encompass radial distribution functions (RDFs), angular distribution functions (ADFs), hydrogen-bonding networks, density profiles, spatial distribution functions (SDFs), and the non-bond energies between H2S and the DES components, all measured at 310 K. Additionally, we calculated the solubility of H2S and CO2 gases as well as the solubility selectivity and diffusivity selectivity parameters to evaluate the performance of the QAS-based DES in sweetening processes of NG. The results represent that eutectic solvents based on quaternary ammonium chloride are effective for H2S adsorption and show selectivity for H2S in gas mixtures. Furthermore, the COSMO-RS model was used to predict the solubility of various gases (H2S/CO2) in the QAS-based DES, providing further insights into their effectiveness.

Energy-saving separation of isobutanol/ethanol/water by extractive distillation with deep eutectic solvents

Energy-saving separation of isobutanol/ethanol/water by extractive distillation with deep eutectic solvents

Co-vulcanization of natural rubber and Eucommia ulmoides gum for mediation of the nonlinear rheology behaviors

Co-vulcanization of natural rubber (NR) and high-moduli Eucommia ulmoides gum (EUG) is promising while the reduction in crystallinity of crosslinked EUG is adverse for developing high-performance materials. Proposed herein is a novel method to prepare high-strength and high-stretchability NR/EUG vulcanizates with rapid vulcanization of EUG into slightly crosslinked particles, followed by further vulcanization of NR to form crosslinked matrix network. Deep eutectic solvents (DESs) are employed to facilitate the vulcanization of EUG during its blending with NR. The two-step vulcanization results in vulcanizates exhibiting superior mechanical properties under shear, tensile, and compressive conditions, significantly exceeding those of vulcanizates prepared by traditional processing methods. The reinforcement mechanism is elucidated by controlling thermomechanical coupling conditions and is supported by comprehensive structural characterizations. It is suggested that the EUG crystalline regions, maintained through the special processing method, work in conjunction with the stress-induced crystallization of the matrix to enhance the vulcanizates, nearly doubling the deformation stress at 800% strain. The crystalline regions can mediate the deformation stress during shear and compression and weaken nonlinear rheological behavior. The established structure-performance relationship is guidable for preparing high-performance NR/EUG blend vulcanizates.

Piperine solubility enhancement via DES formation: Elucidation of intermolecular interactions and impact of counterpart structure via computational and spectroscopic approaches

The development of new forms of existing APIs with enhanced physicochemical properties is critical for improving their therapeutic potential. In this context, ionic liquids (ILs) and deep eutectic solvents (DESs) have gained significant attention in recent years due to their unique properties and potential for solubility enhancement. In this study, we explore the role of different counterparts in the formation of IL/DESs with piperine (PI), a poorly water-soluble drug. After screening a library of fourteen counterpart molecules, ten liquid PI-counterpart systems were developed and investigated. Thermal analysis confirmed the formation of IL/DES, while computational and spectroscopic studies revealed that hydrogen bonding played a crucial role in the interaction between PI and the counterparts, confirming DES formation. The solubility enhancement of PI in these systems ranged from ∼ 36 % to 294 %, with PI-Oxalic acid (OA) exhibiting the highest saturation solubility (49.71 μg/mL) and PI-Ibuprofen (IB) the lowest (17.23 μg/mL). The presence of hydrogen bonding groups in counterparts was key to successful DES formation. A negative correlation was observed between solubility and logP (r = − 0.75, p* = 0.0129), while a positive correlation was found between solubility and normalized polar surface area (PSA) (r = 0.68, p* = 0.029). PI-OA and PI-IB were located at the extreme ends of these regression lines, further validating the relationship between these properties and solubility enhancement. These findings highlight essential aspects of rational IL/DES design, optimizing their properties for broader applications.

Enhancing the biorefinery of brewery spent grain by deep eutectic solvent pretreatment: Optimisation of polysaccharide enrichment through a response surface methodology

One of the main challenges in biorefinery is the efficient fractionation and use of lignocellulosic biomass. In this sense, pretreatment with deep eutectic solvents (DES) is highlighted as a clean and effective separation method, due to its selective solubilisation of hemicellulose and lignin fractions while preserving cellulose. This study presents a process of the enrichment of polysaccharide content and the improvement of enzymatic digestibility using choline chloride (ChCl) and lactic acid (LA) or glycerol (Gly) in brewery spent grain (BSG) pretreatment. Additionally, it describes how improvements can be made in obtaining polysaccharide-rich material through a response surface methodology, this by means of analysing the operational conditions (temperature, reaction time, and molar ratio) using ChCl:LA. The optimised operational conditions (130 °C, 90 min, and 1:8 mol/mol) generate a 75 % enrichment of polysaccharide fraction and the remotion of 77.13 %, 50.70 %, and 100 % of acid-soluble lignin, xylan, and arabinan, respectively. Moreover, the process enhances the saccharification of glucan and xylan to almost 70 % using Cellic CTec2, and to 80 % of glucan and 40 % of xylan using A. niger CECT 2700 enzymatic extract. This constitutes a promising approach to the fractioning of cellulose and lignin from BSG through DES pretreatment, which is unfeasible using traditional pretreatment methods.

Optimizing corncob pretreatment with eco-friendly deep eutectic solvents to enhance lignin extraction and cellulose-to-glucose conversion

Deep eutectic solvents (DES) are an eco-friendly, cost-effective alternative to traditional ionic liquids for biomass pretreatment, with unique characteristics encompassed by hydrogen bond donor (HBD), the molar ratio of hydrogen bond acceptor (HBA) to HBD, temperature, and time affecting efficiency. Despite its potential, a comprehensive study exploring the interplay of these factors is limited. This study explores the optimization of pretreatment variables using choline chloride/lactic acid (1:5) via the response surface method (RSM). It aims to evaluate the effects of time and temperature on lignin extraction, cellulose-to-glucose conversion, and hemicellulose removal. Employing a 22 central composite design with temperature (80–140 °C) and time (2–6 h) as variables, optimal conditions were 123 °C for 6 h. Results include 90.08±1.42 % lignin extraction, 68.77±6.9 % cellulose-to-glucose conversion, and 77.34±0.85 % hemicellulose removal, with 52.52±8.07 % lignin recovery. The fractions of pretreated CC and lignin recovered in the optimal condition found were characterized by X-ray diffraction (XDR), Fourier transform infrared spectroscopy (FTIR), 1H, 13C, 2D-HSQC NMR spectroscopy, Thermogravimetric analysis (TGA/DTG), Gel Permeation Chromatography (GPC) to elucidate chemical characteristics of the materials obtained and facilitate downstream valorization. High efficiency was achieved in lignin extraction and cellulose conversion, and addressing solvent viscosity and DES recycling will further enhance the potential for industrial scalability.

Green extraction of prostaglandin analogs in cosmetics using deep eutectic solvents and detection via LC-MS/MS

Green extraction of prostaglandin analogs in cosmetics using deep eutectic solvents and detection via LC-MS/MS

A deep eutectic solvent with bifunctional acid sites treatment to upgrade a bamboo kraft pulp into a cellulose-acetate grade dissolving pulp

Valorization of non-wood pulp, such as bamboo bleached kraft pulp into high-purity cellulose acetate (CA)-grade dissolving pulp is crucial but challenging in China. Herein, a series of metal salt-based deep eutectic solvents (MSDESs) involving various ZnCl2-urea (U), ZnCl2-glycerol (G), and ZnCl2-lactic acid (LA) are comparatively investigated for this purpose. Thanks to the bifunctional acid sites of Lewis acid ZnCl2 and Brønsted acid LA, the ZnCl2-LA MSDES has the highest acidity (2.62) and interaction affinity to bamboo fibers, leading to the highest efficiency in simultaneous pulp purification and activation. As a result, the resultant upgraded pulp from ZnCl2-LA (DES3-F) features remarkable improvements in purity (from 80.8 % to 93.1 %), intrinsic viscosity (from 897 to 419 mg/L), and reactivity (from 18.1 % to 80.8 %). Moreover, the modified acetate product has a high degree of substitution of 2.84 and a yield of 75.5 %. In short, such a proposed MSDES treatment can offer a promising and alternative approach for the manufacture of high-quality dissolving pulp and its derivatives.

Structural characterization of noni (Morinda citrifolia L.) pectin and its inhibitory activity on pancreatic lipase

This study aimed to investigate the physicochemical properties and biological activities of noni pectin (NP) extracted using various solvents, three fractions of noni pectin were obtained using traditional chemical and deep eutectic solvents. NPs are composed of various ratios of galacturonic acid, arabinose, rhamnose, xylose, glucose, and galactose with different yields, molecular weights, esterification degrees (DE), and microstructures. Among the fractions, noni pectin extracted with Betaine-citric acid (BNP) exhibited higher molecular weight, degree for esterification and pancreatic lipase (PL) inhibitory activity than the other fractions. Enzyme kinetic analysis indicated that BNP inhibited PL via a noncompetitive mechanism. BNP significantly altered the secondary structure of PL and quenched PL fluorescence, suggesting a static quenching mechanism. Isothermal titration calorimetry (ITC) further demonstrated that the binding of BNP to PL was spontaneous and driven by enthalpy, primarily mediated by hydrogen bonding and van der Waals forces. Molecular docking simulations also confirmed strong noncovalent interactions (hydrogen bonding and van der Waals forces) between BNP and PL. This study validated the high efficiency of the deep eutectic solvent-extracted noni pectin fraction in pancreatic lipase inhibition.

Electrochemically assisted preparation of defect-rich Co3O4 electrocatalysts in a water-modified deep eutectic solvent for enhanced oxygen evolution in acid

Co3O4-based electrode materials exhibit great potential for utilization as efficient catalysts for the oxygen evolution reaction (OER), especially in acidic media. However, enhancing their catalytic stability remains a crucial challenge. Herein, we present a facile electrochemical deposition approach coupled with calcination treatment to achieve in-situ growth of active Co3O4 films from a deep eutectic solvent with water as the modifier. The incorporation of water optimizes the structure of fabricated Co3O4 by increasing oxygen vacancies and elevating the Co2+/Co3+ ratio, enabling it to sustain the OER in 0.5 M H2SO4. Impressively, the catalyst grown on Pt/Ti substrate exhibits stable operation over 125 h at 10 mA cm−2. Attenuated total reflection-fourier transform infrared (ATR-FTIR) spectroscopy reveals that OER on the defect-rich Co3O4 catalyst occurs through both lattice oxygen mediated mechanism (LOM) and adsorption evolution mechanism (AEM).

Initial stages of silver electrodeposition on a model Pt(111) single-crystal substrate from ethaline

Deep eutectic solvents (DES) are a new class of solvents with unique properties that are very promising media for the electroplating of metals and alloys. Knowledge about the regularities of metal electrodeposition is noticeably promoted by studies on model single crystal electrodes with a known well-ordered surface structure. In this work, we investigate the regularities of under- and overpotential deposition (upd and opd, respectively) of silver from a silver chloride solution in ethaline on a Pt(111) single crystal surface. For a better understanding of the occurring processes, we employ a complex approach involving electrochemical and in situ and ex situ microscopic techniques. We show that the process of gradual surface poisoning is observed on Pt(111) in the potential range in which no massive solvent degradation is yet observed. We also observe that the extent of this process largely depends on the employed potential of contact between the electrode and the solution and the studied potential range.The presence of Ag upd on Pt(111) in ethaline is demonstrated using voltammetric and in situ STM data. The available results and charge analysis are used to compare the Ag upd processes in ethaline and in aqueous solutions. We discuss the number of Ag adlayers on Pt(111), the effect of the potential of initial contact of the electrode with the solution and cycling history, and the possibility of anion upd and formation of coadsorbate between Ag adatoms and upd chloride anions (chlorine adatoms). We also demonstrate that upd Ag is not completely desorbed until high anodic potentials, where it seems to catalyze the solvent oxidation. Phase deposition of silver from ethaline on Pt(111) starts at almost zero overpotentials, which is probably related to the presence of the already deposited Ag adlayer. Even at very low overpotentials the deposit includes both large planar 2D crystallites and 3D crystallites formed on the surface defects and at the edges of the flat deposit islands. As the overpotential grows, the epitaxiality is gradually lost; the deposit becomes unshaped and the amount of 3D crystallites and their height increase

Retinol-Loaded Deep Eutectic Solvent emulsion: Improved Stability and Therapeutic Efficiency

Retinol is used to manage epidermal and keratin metabolism, promote collagen formation, erase wrinkles for firmer skin, and restore suppleness and smoothness. Retinol can be difficult to store and use owing to the potential for skin irritation, oxidation, and biological ineffectiveness. The linolenic acid and phosphatidylcholine deep eutectic solvent (DES) had a low melting point, high bioactivity, and integrated capsule technology for retinol encapsulation. Safety evaluation tests revealed that the formulated DES-retinol emulsion was less cytotoxic than free retinol, as well as less irritant toward chicken embryos, pig skin, and human patches. In a keratinocyte inflammatory factor inhibition assay, the DES-retinol emulsion reduced monocyte chemoattractant protein-1 expression, indicating the potential to reduce the inflammatory response of the skin to retinol-induced irritation. The DES-retinol emulsion exhibited pro-permeability, anti-wrinkle, firming, and antioxidant characteristics in cellular, skin, and clinical investigations. The DES-retinol emulsion promoted type I collagen production, suppressed matrix metalloproteinase-1 activity, and reduced the release of reactive oxygen species. Consequently, the quantity, size, and depth of wrinkles were substantially improved, along with an enhanced anti-aging effect, heightened skin hydration, increased collagen intensity and flexibility, and diminished retinol-induced irritation. In conclusion, the retinol-loaded linolenic acid and phosphatidylcholine DES emulsion exhibited improved stability, enhanced transdermal efficiency, and notable therapeutic effects.

How does the cation nature affect the DES structure?

The structural properties of three deep eutectic solvents (DESs), namely a 1:2 mixture of urea and choline (Ch) chloride and two analogous DESs containing different cations in place of choline, namely benzyl(2-hydroxyethyl)dimethylammonium (BeH) and benzyltrimethylammonium (Be), were studied by means of Molecular Dynamics simulations. The presence or not of a hydroxyl group on the organic cation, as well as of a bulky substituent such as the benzyl one, was found to strongly affect the DES hydrogen bond network, giving rise to different three dimensional arrangements of all the species present in the systems.

Extraction of mucilage polysaccharides from chia seed by hydrophobic deep eutectic solvents-based three-phase partitioning system: A phase behavior-driven approach

By incorporating the hydrophobic deep eutectic solvents (DESs) into the three-phase partitioning (TPP) technique, a TPP-based method was developed to extract the chia seed polysaccharide (CSP) from chia seed. Through a single-factor experiment and response-surface model, the optimal condition for the TPP extraction was determined as DES composed of dodecanoic acid and octanoic acid in a 1:1 M ratio, (NH4)2SO4 concentration of 32.86 %, crude extract–DES ratio of 0.93 (v/v), aqueous phase pH of 4.38, extraction temperature of 35 °C, and extraction time of 10 min. The polysaccharide yield of the constructed TPP method is 8.65 %, which is higher than the conventional water extraction method (yield is 6.96 %). Molecular dynamics simulations reveal the phase behavior of proteins and polysaccharides in the TPP system, showing that noncovalent interactions play a crucial role in the TPP system. The CSP obtained by the TPP method exhibits distinctive composition, structural, physicochemical, and functional properties, leading to improved thermal stability, rheological behavior, and antioxidant performance. Compared with the traditional extraction method, efficient extraction of CSP can be achieved flexibly using the proposed TPP approach, resulting in high yield and quality of CSP, which provides a new path for the large-scale utilization of chia seed.

DES/O microemulsion for solubilizing and delivering curcumin via the nasal administration to treat acute asthma

As a natural small molecule drug derived from turmeric, curcumin is known for its good biosafety and a range of beneficial effects, including anti-inflammatory, anti-spasmodic, antioxidant, antibacterial, anti-tumor, and neuroprotective effects. Even though, its insolubility in water and instability severely limit its bioavailability and clinical applications. The present study developed a deep eutectic solvent (DES) in oil microemulsion (DES/O-ME) system loaded with Cur for intranasal administration, aiming to enhance both the solubility and permeability of Cur to significantly increase its bioavailability. The project first constructed and screened the optimal choline chloride-based DES. Subsequently, the DES/O-ME system was prepared and optimized to achieve uniform particle size and stability using a pseudo-ternary phase diagram and electrical conductivity measurements. The resulting DES/O-ME system was thoroughly evaluated for its solubilization efficacy, permeability, mucosal cytotoxicity, and stability. Additionally, the therapeutic efficacy of the Cur-DES/O-ME was assessed in vivo using a murine model of allergic asthma. This comprehensive evaluation highlights the potential of the DES/O-ME system as a promising intranasal drug delivery platform to overcome the limitations of curcumin’s bioavailability and clinical application.

One-step electrodeposition of reduced graphene oxide-amorphous carbon composite coatings for proton exchange membrane fuel cell bipolar plates

In this paper, a convenient electrodeposition method is proposed to directly fabricate a reduced graphene oxide-amorphous carbon composite coating (rGO-ACC) on a 316L stainless steel substrate. The rGO-ACC coating is achieved through a one-step reduction by utilizing a choline chloride-ethylene glycol deep eutectic solvent (DES) with the dispersion of graphene oxide. The analysis results from SEM, Raman and XPS reveal that the obtained rGO-ACC coating, with layered wrinkle morphology, uniformly covers and covalently bonds to 316L stainless steel substrate. Potentiodynamic and potentiostatic polarization tests showed that the corrosion current densities of rGO-ACC coated 316L stainless steel were of the order of 10-7 A cm−2 in simulated proton exchange membrane fuel cells (PEMFC) working environment, indicating a significant improvement of corrosion resistance of 316L and an excellent electrochemical stability. Meanwhile, compared with the naked 316L steel, the interfacial contact resistance (ICR) of the coated stainless steel is significantly reduced due to the outstanding electrical conductivity of the coated rGO. The results manifested that deposited rGO-ACC on steel surface may be a highly promising modification method for PEMFC metal bipolar plates.

Stable and environmentally benign nanofluids for direct absorption solar collectors based on natural deep eutectic solvents

Stable and environmentally benign nanofluids for direct absorption solar collectors based on natural deep eutectic solvents

An eco-friendly strategy for emerging contaminants removal in water: Study of the adsorption properties and kinetics of self-polymerized PHEMA in green solvents

Water contaminants severely affect human health and aquatic ecosystems, and adsorption poses an economic, available, and feasible technology for remediation that needs to be accompanied by eco-friendly and sustainable materials. This study proposes an eco-friendly strategy for removing emerging contaminants using polyhydroxyethyl methacrylate polymers synthesized by self-polymerization with hydrophilic first-generation deep eutectic solvents. The polymers were characterized using structural and physical characterization techniques and their adsorption capacity against four emerging contaminants: a non-steroidal anti-inflammatory drug, an antibiotic, a pesticide, and a non-ionic surfactant. The experimental results showed high adsorption capacity for the urea: choline chloride-derived polymer with 6.21, 7.19, 6.01, and 6.99 mg⋅g-1 for paracetamol, ciprofloxacin, glyphosate, and triton X-100, respectively; these values are comparable to those obtained for similar systems. Kinetic, isothermal, and thermodynamics were also studied using various mathematical models to understand the adsorption mechanism, further complemented by DFT analysis. Chemisorption was found to be the primary mechanism by exothermic and ordered processes, which is thermodynamically favored. The study demonstrated for the first-time the effectiveness of self-polymerized PHEMA without chemical modification as a reusable adsorbent material and its ability to remove different types of emerging contaminants, thereby offering a promising solution for water treatment in environmental science.

Amine-based deep eutectic solvents for CO2 capture: Experiments and molecular thermodynamics

Amine-based deep eutectic solvents for CO2 capture: Experiments and molecular thermodynamics

Efficient extraction of 5-hydroxymethylfurfural from multi-components aqueous solution by hydrophobic deep eutectic solvents

Efficient extraction of 5-hydroxymethylfurfural from multi-components aqueous solution by hydrophobic deep eutectic solvents