Glycerol Deep Eutectic Solvent Research Articles

Nitrogen-doped carbon quantum dots based on deep eutectic solvents precursors to detect Cr6+ in environmental water

Hexavalent chromium is the main compound in industrial wastewater, which is highly toxic and seriously pollutes the environment and endangers human health. The excellent fluorescence performance of carbon quantum dots (CQDs) is widely used to detect heavy metal ions. Carbon quantum dots (CQDs) with excellent fluorescence performance is widely used to detect heavy metal ions. However, the quantitatively structure of CQDs is different to control in the formation due to the uncertain-complex of biomass-based materials. In this work, nitrogen-rich CQDs (N-CQDs) based on 4-A-1,2,4-TZ and glycerol deep eutectic solvents (DESs) was prepared by one-step hydrothermal method. The prepared N-CQDs exhibited excellent fluorescence stability. The response of the N-CQDs to Cr6+ was linear in the range of 5–100 μM and a detection limit of 0.7043 μM. The results show that N-CQDs can achieve the detection of Cr6+ well. Satisfactory recovery of Cr6+ was also obtained by measuring in the wastewater.

Choline chloride plus glycerol deep eutectic solvents as non-aqueous absorbents for the efficient absorption and recovery of HCl gas

The use of ChCl-based DESs as non-aqueous absorbents for the efficient absorption and recovery of pure HCl gas.

Immobilization of Pseudomonas stutzeri lipase through Cross-linking Aggregates (CLEA) for reactions in Deep Eutectic Solvents

The use of deep eutectic solvents (DES) with buffer as cosolvent (up to 10 % v/v) leads to low-viscous media in which lipases can perform synthetic reactions, instead of hydrolysis. This paper explores the immobilization of Pseudomonas stutzeri lipase (TL) in cross-linking aggregates (CLEA) to deliver robust derivatives that are active in media like choline chloride – glycerol DES with buffer as cosolvent. While the free TL enzyme was markedly inactive in these media, TL-CLEA derivatives perform esterifications and can be reused several times. Overall, results are consistent with previous experiments reported for other lipases in these DES-water media and confirm that CLEA immobilization turns out a very useful and straightforward alternative for generating active (bio)catalysts for DES-aqueous media systems. Immobilized systems open the possibility of performing continuous processes in low-viscous DES-buffer media.

Astaxanthin Recovery from Shrimp Residue by Solvent Ethanol Extraction Using Choline Chloride:Glycerol Deep Eutectic Solvent as Adjuvant

The present study investigated the use of choline chloride:glycerol deep eutectic solvent as an adjuvant for tuning the ethanol extraction of astaxanthin from Litopenaeus vannamei processing residues. The adjuvant concentration did not show a clear trend on the total carotenoid, however, the addition of adjuvant proved to be advantageous in the ultrasound-assisted experiments. In order to establish a balance between total carotenoid and productivity, an operational condition with ultrasound, 5% (m/v) choline chloride:glycerol and 10 min of incubation was selected, which provided 737.69 μg g-1 total carotenoids and 32.71 μg g-1 astaxanthin. When compared to the astaxanthin standard, the shrimp residue extract obtained greater antioxidant activity in free radical scavenging tests. In addition, the shrimp residue extract dramatically reduced the dosage of norfloxacin (up to 87.5%) and gentamicin (up to 75.0%) antibiotics in tests to inhibit the growth of gram-negative bacteria.

The effect of the triethanolamine: glycerol deep eutectic solvent on the yield, fatty acid composition, antioxidant activity, and physicochemical properties of black mustard (Brassica nigra L.) seed oil

This study reports the yields, physicochemical properties, fatty acid compositions, and antioxidant activities of black mustard (Brassica nigra L.) seed oils extracted by cold pressing and the solvent extraction using different solvents (n–hexane, trichloroethylene, and a mixture of trichloroethylene and the triethanolamine:glycerol deep eutectic solvent (TEOA:G DES) with no or after pretreatment with the TEOA:G DES. Density (0.9791 ± 0.0003–0.9851 ± 0.0003 g/cm3), viscosity (121.15 ± 1.62–123.32 ± 0.10 mPa⋅s), boiling point (179–185 ± 1 °C), refractive index (1.4692 ± 0.0006–1.4758 ± 0.0011), acid (2.08 ± 0.19–3.22 ± 0.15 mg KOH/g), iodine (99.2 ± 1.6–105.4 ± 1.5 g I2/100 g), peroxide (1.68 ± 0.01–1.82 ± 0.03 mmol O2/kg), and saponification values (165.1 ± 2.7–169.4 ± 2.3 mg KOH/g), fatty acid composition and antioxidant activity of the extracted oil were determined in order to evaluate its potential use as a foodstuff, a pharmaceutical or a feedstock for biodiesel production. Although the maceration of black mustard seeds with sole trichloroethylene yielded the highest oil yield of 31.10 ± 0.42 g/100 g, it required almost twice the volume of trichloroethylene compared to the volume applied in the macerations after the pre–treatment with the TEOA:G DES and with the mixture of trichloroethylene/TEOA:G DES. The oil extracted by the extraction in the presence of TEOA:G DES has similar physicochemical properties but better antioxidant activity than the oil extracted by cold pressing.

Deep Eutectic Solvent-Mediated Hierarchically Structured Fe-Based Organic–Inorganic Hybrid Catalyst for Oxygen Evolution Reaction

The genuine active sites toward oxygen evolution reaction (OER) are usually generated via the in situ transformation of initial electrocatalysts during anodic oxidation. In principle, all the catalysts possessing such a transition might be active toward OER. However, current OER electrocatalysts are still mainly limited in metal oxides, (oxy)hydroxides, phosphides, and chalcogenides, etc. Little attention is paid to the rational design of electrocatalysts based on the transformation-induced strategy. Herein, we demonstrated a Fe-based organic–inorganic hybrid strategy for the construction of OER electrocatalysts based on the in situ transformation. Hierarchically three-dimensional (3D) iron alkoxides of glycerol were synthesized in choline chloride (ChCl)/glycerol deep eutectic solvent (DES). During the OER, the as-prepared Fe-based organic–inorganic hybrid can transform into FeOOH, an active species for electrocatalysis, exhibiting sustainable electrocatalytic performance. It only requires 280 mV to offe...

Polymer solvation in choline chloride deep eutectic solvents modulated by the hydrogen bond donor

Choline chloride (ChCl) Deep Eutectic Solvents (DESs) are a relatively new class of ionic fluid physicochemically similar to ionic liquids. Their properties, combined with their hydrogen bond - rich bulk nanostructures make them attractive alternatives as molecular solvents for a range of applications. Nevertheless, the solvation structure of molecular and polymer solvents in choline chloride DES remains largely uncharacterised due to the complexity of the DES nanostructure itself. We present a systematic quantum chemical investigation of the solvation structure of poly(ethylene glycol) (PEO) in DES formed by ChCl and urea, ethylene glycol and glycerol hydrogen bond donors. Trends in the solvation structure of PEO correlate with the density of the DES hydrogen bond network, and the extent to which this network can be perturbed by the polymer solute. We show that both of these factors are modulated by the type of hydrogen bond donor itself. Notably, PEO disrupts the urea – choline hydrogen bond network. This disruption leads to a more highly structured solvation environment for the polymer, which is forced into a relatively constrained, coiled morphology. By contrast, the disruption to the hydrogen bond networks in the ethylene glycol and glycerol DES are less significant, leading to a less constrained environment.

Efficient and reversible absorption of NH3 by functional azole–glycerol deep eutectic solvents

The hydrogen bond donor (HBD) of glycerol and hydrogen bond acceptor (HBA) selected from azole compounds were paired to construct functional deep eutectic solvents (DESs) as NH3 absorbents.

In Vitro Antifungal Activity of Composites of AgNPs and Polyphenol Inclusion Compounds against Fusarium culmorum in Different Dispersion Media

Fusarium culmorum is a soil-borne fungus able to cause Fusarium head blight, one of the most important cereal diseases worldwide, which can result in significant yield losses of up to 50% and which jeopardizes food and feed safety due to the mycotoxins produced. In the study presented herein, the enhancement of the antifungal activity against this pathogen, resulting from the addition of silver nanoparticles (AgNPs) to different polyphenol-stevioside inclusion compounds, dispersed either in a chitosan oligomers hydroalcoholic solution or in a choline chloride:urea:glycerol deep eutectic solvent, was investigated in vitro. The polyphenols assayed were curcumin, ferulic acid, gallic acid and silymarin. Four composite concentrations (62.5, 125, 250 and 500 µg·mL−1), with and without AgNPs, were assessed, finding noticeable differences in mycelial growth inhibition, with EC50 and EC90 values ranging from 118 to 579 µg·mL−1 and from 333 to 2604 µg·mL−1, respectively. The obtained results evidenced the improved efficacy of the composites with AgNPs, a superior performance of the composites based on curcumin and ferulic acid, and the advantages of the deep eutectic solvent-based dispersion medium over the chitosan oligomers-based one. The reported composites hold promise for crop protection applications.

Silver Nanoparticles and Polyphenol Inclusion Compounds Composites for Phytophthora cinnamomi Mycelial Growth Inhibition.

Phytophthora cinnamomi, responsible for “root rot” or “dieback” plant disease, causes a significant amount of economic and environmental impact. In this work, the fungicide action of nanocomposites based on silver nanoparticles and polyphenol inclusion compounds, which feature enhanced bioavailability and water solubility, was assayed for the control of this soil-borne water mold. Inclusion compounds were prepared by an aqueous two-phase system separation method through extraction, either in an hydroalcoholic solution with chitosan oligomers (COS) or in a choline chloride:urea:glycerol deep eutectic solvent (DES). The new inclusion compounds were synthesized from stevioside and various polyphenols (gallic acid, silymarin, ferulic acid and curcumin), in a [6:1] ratio in the COS medium and in a [3:1] ratio in the DES medium, respectively. Their in vitro response against Phytophthora cinnamomi isolate MYC43 (at concentrations of 125, 250 and 500 µg·mL−1) was tested, which found a significant mycelial growth inhibition, particularly high for the composites prepared using DES. Therefore, these nanocomposites hold promise as an alternative to fosetyl-Al and metalaxyl conventional systemic fungicides.

Amphiphilically Nanostructured Deep Eutectic Solvents.

Deep eutectic solvents (DESs) are neoteric liquids produced by mixing a high-melting-point salt and a molecular hydrogen-bond donor. Amphiphilic (self-assembled) liquid nanostructure, which is key for many of the useful properties of the related ionic liquid class, has not previously been experimentally demonstrated in DESs. Here we show how amphiphilically nanostructured DESs can be prepared using primary ammonium cations. The bulk structure of alkylammonium bromide (alkyl = ethyl-, propyl-, and butyl) and glycerol DESs at a 1:2 mol ratio is examined using neutron diffraction and empirical potential structure refinement fitting. Analysis reveals cation alkyl chain association, which is the signature of amphiphilic liquid nanostructure, in all systems, which becomes better defined with increasing chain length. The ability to form amphiphilically nanostructured DESs will enable the translation of ionic liquid properties associated with liquid nanostructure to DESs.

Tetramethylammonium chloride + glycerol deep eutectic solvent as separation agent for organic liquid mixtures: Assessment from experimental limiting activity coefficients

Solute retention data acquired by gas-liquid chromatography were used to determine the activity coefficients at infinite dilution for 24 organic solutes in the deep eutectic solvent (DES) consisting of tetramethylammonium chloride and glycerol in a molar ratio of 1.001:2. The organic solutes included alk-1-anes, alk-1-enes, alk-1-ynes, cycloalkanes, alkanols, alkylbenzenes, ketones, esters and heterocyclics. The measurements were undertaken at four different temperatures, viz T = (313.15, 323.15, 333.15 and 343.15) K with an estimated uncertainty of ±3.8%. From the experimental infinite dilution activity coefficient data, the values of partial molar excess enthalpy at infinite dilution were calculated using Gibbs Helmholtz relationship. Limiting selectivity and capacity values were also calculated from experimental limiting activity coefficients and compared to those of other separation agents, including other deep eutectic solvents, ionic liquids and industrial molecular agents. Results obtained in this study indicate that tetramethylammonium chloride + glycerol DES can potentially be used as an alternative solvent for nitrogen and sulphur removal from transportation fuels as well as the separation of cycloalkanes, aromatics and esters from light alkanols.

The physicochemical and thermodynamic properties of the choline chloride-based deep eutectic solvents

This paper reports the physicochemical (density, dynamic viscosity, electrical conductivity and refractive index) and the thermodynamic (thermal expansion coefficient, molecular volume, lattice energy and heat capacity) properties of several choline chloride (ChCl) based deep eutectic solvents (DESs), with 1:2 mole ratio, respectively: ChCl:propylene glycol, ChCl:1,3-dimethylurea and ChCl:thiourea, at atmospheric pressure as a function of temperature over the range of 293.15?363.15 K. Their properties were also compared with those of some already characterized ChCl-based DESs, namely ChCl:ethylene glycol, ChCl:glycerol and ChCl:urea (1:2 mole ratio). Density, viscosity and refractive index of all DESs decrease with the increasing temperature while the electrical conductivity increases. Viscosity and conductivity of the tested DESs were fitted by both Arrhenius-type and Vogel?Tamman?Fulcher equations. The changes of molar enthalpy, entropy and Gibbs energy of activation, determined using the Eyring theory, demonstrated the interactional factor as predominant over the structural factor for all DES systems. The fractional Walden rule, used to correlate molar conductivity and viscosity, showed an excellent linear behaviour. It was shown that ChCl:propylene glycol DES had properties similar to ChCl:ethylene glycol and ChCl:glycerol DESs. However, the properties (density, viscosity and electrical conductivity) of ChCl:1,3-dimethylurea and ChCl: :thiourea DESs were inferior to those of the ChCl:urea DES.

Micellization of alkyltrimethylammonium bromide surfactants in choline chloride:glycerol deep eutectic solvent.

Deep eutectic solvents have shown the ability to promote the self-assembly of surfactants in solution. However, some differences have been found compared with self-assembly in pure water and other polar organic solvents. The behaviour of alkyltrimethylammonium bromides in choline chloride:glycerol deep eutectic solvent has been studied by means of surface tension, X-ray and neutron reflectivity and small-angle neutron scattering. The surfactants were found to remain surface active and showed comparable critical micelle concentrations to the same surfactants in water. Our scattering studies demonstrate that these surfactants form globular micelles with ellipsoidal shape in solution. The size, shape and aggregation number of the aggregates were found to vary with the chain length of the surfactant. Specific solvent-headgroup interactions were not found in this system, unlike those we have previously postulated for anionic surfactants in choline chloride deep eutectic solvents.

Evidence of self-aggregation of cationic surfactants in a choline chloride+glycerol deep eutectic solvent.

Based on fluorescence probe, electrical conductivity, surface tension, small-angle X-ray/dynamic light scattering, and transmission electron microscopy experiments, we present the first clear lines of evidence for self-aggregation of cationic surfactants of the n-alkyltrimethylammonium family within an archetypical deep eutectic solvent comprised of a 1:2 molar mixture of choline chloride and glycerol. Estimated thermodynamic parameters suggest this self-aggregation process to be less entropically driven than that in water. These novel water-free self-assemblies might serve as dynamic soft templates to direct the growth of size- or shape-tailored nanoparticles within water-restricted media.

Efficient SO2 absorption by renewable choline chloride–glycerol deep eutectic solvents

The utilization of cheap and renewable materials is an important topic in green chemistry. In this work we studied the absorption of SO2 by choline chloride (ChCl)–glycerol deep eutectic solvents (DESs) at various temperatures and SO2 partial pressures, and the molar ratios of ChCl and glycerol ranged from 1 : 4 to 1 : 1. It was demonstrated that the solubility of SO2 in the DESs increased as the ChCl concentration in the DESs increased. The SO2 absorption capacity of the DESs with a ChCl–glycerol molar ratio of 1 : 1 could be as high as 0.678 g SO2 per g DES at 20 °C and 1 atm. Moreover, the absorbed SO2 could be easily released, and their excellent properties of high absorption capacity and rapid absorption/desorption rates remained during the five consecutive absorption/desorption cycles. The Henry's constants of SO2 in the DESs were calculated based on the solubility data.