Self-assembly of cationic surfactant in choline chloride-based deep eutectic solvents: structural solvation and dynamics.

Investigating the effect of systematically modifying the molar ratio of hydrogen bond donor and acceptor on solvation characteristics of deep eutectic solvents formed using choline chloride salt and polyalcohols

The effects of a hydrogen bond acceptor and hydrogen bond donor on carbon dioxide absorption via natural deep eutectic solvents were studied in this work. Naturally occurring non-toxic deep eutectic solvent constituents were considered; choline chloride, b-alanine, and betaine were selected as hydrogen bond acceptors; lactic acid, malic acid, and fructose were selected as hydrogen bond donors. Experimental gas absorption data were collected via experimental methods that uses gravimetric principles. Carbon dioxide capture data for an isolated hydrogen bond donor and hydrogen bond acceptor, as well as natural deep eutectic solvents, were collected. In addition to experimental data, a theoretical study using Density Functional Theory was carried out to analyze the properties of these fluids from the nanoscopic viewpoint and their relationship with the macroscopic behavior of the system, and its ability for carbon dioxide absorption. The combined experimental and theoretical reported approach work leads to valuable discussions on what is the effect of each hydrogen bond donor or acceptor, as well as how they influence the strength and stability of the carbon dioxide absorption in deep eutectic solvents. Theoretical calculations explained the experimental findings, and combined results showed the superiority of the hydrogen bond acceptor role in the gas absorption process, with deep eutectic solvents. Specifically, the cases in which choline chloride was used as hydrogen bond acceptor showed the highest absorption performance. Furthermore, it was observed that when malic acid was used as a hydrogen bond donor, it led to low carbon dioxide solubility performance in comparison to other studied deep eutectic solvents. The cases in which lactic acid was used as a hydrogen bond donor showed great absorption performance. In light of this work, more targeted, specific, deep eutectic solvents can be designed for effective and alternative carbon dioxide capture and management.

Insights into the enhanced thermal stability of lysozyme with altered structure and activity induced by choline chloride-based deep eutectic solvents containing polyols and sugars

Thin Ni and Cr coatings are commonly electrodeposited from aqueous electrolytes [1,2]. These often contain series of additives, whose role is to improve the leveling and adhesion of deposited films to the substrate, decrease internal stress, and limit the hydrogen evolution reaction (HER). However, certain additives, such as thiourea as well as Cr(VI) compounds are highly hazardous [1,2]. Therefore, due to the increasing environmental awareness of the society, the electrolytes containing these constituents require replacement by green alternatives, such as Deep Eutectic Solvents (DESs).DESs, usually composed of quaternary ammonium salt and hydrogen bond donor, i.e. ethylene glycol, have wider electrochemical potential window than H2O, which in principle enables obtaining metallic coatings without the HER [3]. However, due to the low conductivity and high viscosity of DESs, it is necessary to use additives, i.e. nicotinic acid, improving these physico-chemical properties and enhancing the electrodeposition process. However, due to the unavoidable presence of water (DESs are hygroscopic), H2O can be considered an additive to DESs. The addition of H2O can be beneficial since it improves the ion mobility, and therefore increases the reduction rate [4]. The current studies focus on understanding the effect of water content on the physico-chemical properties, and the structure of DESs. However, a little is known on the influence of H2O on the electrodeposition of Ni and Cr, especially on the nucleation and growth, the effect of the morphology and chemical composition of deposited films. Therefore, an in-depth study on this topic is required.The electrolytic reduction of Ni and Cr cations in choline chloride – ethylene glycol (1ChCl:2EG) on glassy carbon and steel substrates was investigated in function of water content. This study was performed by means of electrochemical techniques, such as linear sweep voltammetry and chronoamperometry. The obtained deposits were analyzed with surface sensitive methods, i.e. scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. In order to bring the understanding on the influence of H2O as an additive on the early stage electrodeposition of Ni and Cr from DES, a combination of computational modelling with UV-vis spectroscopy was involved. This approach allowed correlating the observed electrochemical behavior of Ni and Cr cations with certain water concentrations. Establishing such relationship is of high relevance, as it may enable optimizing the process parameters for Ni and Cr electroreduction from DESs. [1] N. V. Mandich and D. L. Snyder. Modern Electroplating, chapter Electrodeposition of Chromium, pages 205–248. John Wiley & Sons, Inc., New Jersey, 5 edition, 2010.[2] G. DiBari. Modern Electroplating, chapter Electrodeposition of Nickel, pages 79-114. John Wiley & Sons, Inc., New Jersey, 5 edition, 2010.[3] E.L. Smith, A.P. Abbot, K.S. Ryder, Deep Eutectic Solvents (DESs) and Their Application, American Chemical Society Publications, 2014, pp. 11060 – 11082.[4] M. Lukaczynska, E.A. Mernissi Cherigui, A. Ceglia, K. Van den Bergh, J. De Strycker, H. Terryn, and J. Ustarroz, Influence of water content and applied potential on the electrodeposition of Ni coatings from deep eutectic solvents, Electrochimica Acta, 319: 690-704, 2019.

Modeling the ammonia absorption capacity of choline chloride-based deep eutectic solvents with artificial neural networks

A series of deep eutectic solvents (DESs) were prepared using glycerol and choline chloride (ChCl), and Fourier transform infrared spectrometer (FT-IR) was used to analyze the spectra of glycerol, choline chloride and DESs based on glycerol and choline chloride. Then DESs were used as the additives of mobile phase to optimize chromatographic behavior of caffeic acid in high performance liquid chromatography (HPLC). A 17-run Box-Behnken design (BBD) was employed to evaluate effect of DESs as additives by analyzing the maximum theoretical plate number. Three factors, reaction temperature (60 °C, 80 °C, 100 °C), molar ratio of glycerol and choline chloride (2 : 1, 3 : 1, 4 : 1, n/n), and volume percent of additives (0.05%, 0.10%, 0.15%, v/v), were investigated in BBD. The optimum experiment condition was that of reaction temperature (80 °C), molar ratio of glycerol and ChCl (3 : 1, n/n), and volume percent of additive (0.10%, v/v). The mean chromatographic theoretical plate number of the caffeic acid this condition was 1567.5, and DESs as additives shorten the retention time and modify the chromatogram shape, proving DESs as additives for effective theoretical plate number and column efficiency in HPLC.

Celecoxib solubility in two choline chloride-based deep eutectic solvents- Experimental study, thermodynamic modeling, and molecular dynamic simulation

Extraction and characterization of lignin from lignocellulose biomass using citric acid and fructose-based NADES.

The present study reports the result of the measurement and analysis of the solubility curve and tie-line data of four ternary systems containing heptane–isopropyl alcohol azeotrope mixtures and deep eutectic solvents (DESs) at T = 298.2 K and p = 0.1 MPa. This investigation is aimed to evaluate the efficiency of the prepared DESs as extractants in the separation of the heptane–alcohol azeotropic mixtures through liquid–liquid extraction (LLE) processes. In this study, four choline chloride-based DESs were prepared by a heating process. Two hydrogen bond donor (HBD) compounds (i.e., ethylene glycol and propylene glycol) were chosen in the preparation of the DESs. The solubility curves show that the effect of DESs on the immiscibility region is small. The studied systems display the type-1 LLE behavior. The measured tie-line values were adequately fitted through the nonrandom two-liquid (NRTL) thermodynamic model, and the interaction parameter values were determined. The correlation data appeared to be in good agreement with the measured tie-lie data. The extraction capacity (distribution constants and selectivities) of the studied DESs was determined. The DESs had high and similar selectivity values for the studied systems. Moreover, the distribution constants were larger than unity, indicating a favorable solvent-to-feed ratio.

Effects of deep eutectic solvent (DES) treatment were determined for the chemical composition of the sapwood and heartwood of red pine (Pinus densiflora). Two DES systems were made from the mixture of choline chloride (ChCl) and two different hydrogen bond donors (HBDs), namely, lactic acid (LA) and glycerin (GLY), with different molar ratios (1:2, 1:6, and 1:10). The yield of the solid residue after DES treatment decreased with an increase in the HBD concentration and treatment time, indicating that the water-soluble fraction was increased. The amount of solid residue was lower in the DES with LA than in DES with GLY, and higher in sapwood than in heartwood during both DES treatments. There was no substantial change in the lignin content of the samples, each being 24.7 to 29.5 wt.%, based on the mass of the treated product. Similar to the yield of the solid residue, cellulose and hemicellulose content in the treated product decreased with an increase in the HBD concentration and treatment time, and it was higher in sapwood than in heartwood. The cellulose crystallinity exhibited a slight increase with increasing treatment time, but there was no difference among the treatments using different molar ratios and between sapwood and heartwood.

Comprehensive exploration of the adsorption capacity of innovative betaine-based deep eutectic solvents for carbon dioxide capture

Gallic acid (GA) (3,4,5-trihydroxybenzoic acid), which is a natural secondary metabolite and widely isolated from various plants, is for the first time employed as a hydrogen bond donor (HBD) for preparing a deep eutectic solvent (DES) with choline chloride (ChCl) as a hydrogen bond acceptor (HBA). This DES has been applied as an extractant to separate gycerol from biodiesel. The finding indicates that a DES could be formed at a molar ratio of ChCl to GA of 5 : 1, 6 : 1, and 7 : 1. The characterization of the synthesized DES shows its acidic polar property with a pH of lower than its constituents, density of lower than biodiesel, and the viscosity within the range reported for previously prepared DES. Functional groups analysis using FTIR indicated the presence of all functional groups from GA and ChCl in the DES structure, along with the absence of any new spectral peaks, suggesting that there was no chemical reaction involved in the DES formation. Its ability to reduce the glycerol concentration in the biodiesel in the range of 74.6 to 99.8 % denotes its capability as a potential extractant for separation of glycerol from biodiesel.

Redox and emission characteristics of Eu3+ in deep eutectic solvent: Unraveling the hidden potential of DES as luminescent media

This study investigates the effect of using water as a low-viscosity component in ternary amine-based deep eutectic solvents (DESs) on the physicochemical properties, thermal stability, and CO2 absorption capacity of the resulting DESs. It should be emphasized that water is a component of the ternary DES. The effect of water content in the DES, type of hydrogen bond acceptors (HBAs), hydrogen bond donors (HBDs), and HBA:HBD ratio on the above parameters was investigated. Moreover, the effect of temperature and pressure on the CO2 absorption capacity of DESs was predicted using the predictive model COSMO-RS. This model was also used to predict the CO2 solubility in the DESs and the results were compared with the experimental values. The results showed that the addition of small amounts of water, e.g., 5 and 10 wt% during preparation, can significantly decrease the viscosity of the resulting DESs, up to 25% at room temperature, while maintaining the high CO2 absorption capacity and high thermal stability. The ternary DESs based on MEA exhibited a high CO2 absorption capacity of 0.155–0.170 g CO2 / g DES. The ternary DESs were found to be thermally stable with a decomposition temperature of 125°C, which promotes the use of such solvents in post-combustion capture processes. Finally, COSMO-RS proved to be a suitable tool for qualitative prediction of CO2 solubility in DESs and demonstration of trends related to the effects of temperature, pressure, molar ratio, water content, HBD and HBA on CO2 solubility.

Deep eutectic solvents (DESs), a new class of green solvents, have attracted considerable attention for CO2 capture. In this study, we synthesised DESs using a superbase, 1,5-diazabicyclo [4.3.0] non-5-ene (DBN), as the hydrogen bond acceptor and a weak acid, diethylene glycol (DEG), as the hydrogen bond donor in different molar ratios to achieve efficient and reversible CO2 absorption. Experimental results indicate that DES2 (DBN:DEG = 1:2) exhibits optimal CO2 absorption performance (a maximum absorption capacity of 0.275 gCO2/gDES. Deep eutectic solvents at 30°C and flow rate of 30 mL/min). Nuclear magnetic resonance (NMR) spectroscopy reveals that DEG activated by DBN in DESs can react with CO2 to form carbonates, thereby enabling CO2 capture. In addition, monoethanolamine was added to the DESs as a promoter, thereby enhancing the CO2 absorption performance, with a maximum absorption capacity of 0.316 gCO2/gDES. 13C NMR and Fourier transform infrared analyses revealed that the amino and hydroxyl groups in the DESs can simultaneously react with CO2 to form carbamate and carbonate, achieving synergistic absorption.