Application of deep eutectic solvents and their individual constituentsas surfactants for enhanced oil recovery (original) (raw)
Fluid Phase Equilibria, 2017
Several novel applications of Deep Eutectic Solvents (DESs) have emerged recently. With a growing interest in the field, there is an urge to understand formation and functioning of these solvents at molecular level, which in turn would assist in further designing of DESs. We herein performed molecular dynamics simulations on three of the commonly used type III DES, viz, reline, ethaline, and glyceline, which are mixtures of urea, ethylene glycol, and glycerol with choline chloride at eutectic composition. Our results explain the role of inter-molecular and intra-molecular hydrogen bonding and energies on formation of these DESs. Furthermore, the ability of these DESs to be altered in a desired way through a simple addition of water makes it versatile solution for several other applications. Hence, simulations are also performed on the aqueous DES solutions, which reveal the effect of water on intermolecular network of interaction existing within these DESs.
Effect of Water on a Hydrophobic Deep Eutectic Solvent
Deep eutectic solvents (DESs) formed by hydrogen bond donors and acceptors are a promising new class of solvents. Both hydrophilic and hydrophobic binary DESs readily absorb water, making them ternary mixtures, and a small water content is always inevitable under ambient conditions. We present a thorough study of a typical hydrophobic DES formed by a 1:2 mole ratio of tetrabutyl ammonium chloride and decanoic acid, focusing on the effects of a low water content caused by absorbed water vapor, using multinuclear NMR techniques, molecular modeling, and several other physicochemical techniques. Already very low water contents cause dynamic nanoscale phase segregation, reduce solvent viscosity and fragility, increase self-diffusion coefficients and conductivity, and enhance local dynamics. Water interferes with the hydrogen-bonding network between the chloride ions and carboxylic acid groups by solvating them, which enhances carboxylic acid self-correlation and ion pair formation between tetrabutyl ammonium and chloride. Simulations show that the component molar ratio can be varied, with an effect on the internal structure. The water-induced changes in the physical properties are beneficial for most prospective applications but water creates an acidic aqueous nanophase with a high halide ion concentration, which may have chemically adverse effects.
Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, six deep eutectic solvents (DESs) were prepared namely allyltriphenyl phosphonium bromide- diethylene glycol (ATPPB-DEG) and allyltriphenyl phosphonium bromide - triethylene glycol (ATPPB-TEG) using three molar ratios of 1:4, 1:10 and 1:16 salt to HBDs. The temperature range for experimental viscosity was from 293.15 to 343.15 K and that of the experimental surface tension was between 298.15 and343.15 K. The results disclosed that hydrogen bonding (H…Br) in DESs has a great effect on the properties. Among all DESs with the same components, the DESs with the strong hydrogen bonding (H…Br) in their structures had the higher viscosity and surface tension. Besides, by increasing the temperature and quantity of HBDs in DESs, both of these properties experienced a decrease decreasing trend in the amount. It was found that the molecular weight of DESs with the same component has an effect on the properties. The higher molecular weight caused the higher viscosity and surface tension. Further, ATPPB-TEG DESs had the higher viscosity and lower surface tension than ATPPB-DEG DESs because of the higher alkyl chain in their structures. Several models and a new empirical equation were used to correlate the experimental viscosity data. It was found that there is a well agreement between theoretical and experimental values especially when the new empirical equation is used. In addition, the activation parameters for all DESs were calculated using the experimental viscosity data and application of Eyring’s absolute rate theory. The experimental surface tension was employed to predict the critical temperature and, surface entropy and internal surface energy of DESs. Finally, two empirical equations were used for relating the experimental surface tension to the experimental viscosity of DESs.
Deep eutectic solvents (DESs) are derived from two or more salts as the hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). In this work, DES namely allyltriphenyl phosphonium bromide-diethylene glycol (ATPPB-DEG) was prepared by using three molar ratios of 1:4, 1:10 and 1:16 salt to HBD. The volumetric properties of aqueous DESs, such as density, molar volume, isobaric thermal expansion, apparent molar volume and apparent molar expansibility were reported at several temperatures from 293.15 to 343.15 K. A mathematical equation, namely Jouyban-Acree model (JAM), was used for the first time to correlate the experimental density and molar volume data of aqueous solution of DESs with respect to the concentration and temperature. The results disclosed that this model is an accurate and reliable model for the prediction of aqueous DES properties. The excess properties, such as excess molar volume and excess isobaric thermal expansion were reported and fitted to two different equations. In order to calculate the limiting apparent molar volume values, the apparent molar volume values were fitted into a Redlich-Mayer equation. By applying the Hepler equation, it was found that DESs with molar ratios of 1:4 and 1:10 are as structure-maker solutes, while the DES 1:16 is a structure-breaking solute in aqueous solutions at different temperatures.
Journal of Molecular Structure, 2020
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Glycerol-based deep eutectic solvents: Physical properties
Journal of Molecular Liquids, 2016
Deep eutectic solvents (DESs) have been used in many industrial applications. DES is a mixture of a salt and a hydrogen bond donor (HBD). In this study, 70 DESs were synthesized successfully based on glycerol (Gly) as the HBD with different phosphonium and ammonium salts, namely methyl triphenyl phosphonium bromide (MTPB), benzyl triphenyl phosphonium chloride (BTPC), allyl triphenyl phosphonium bromide (ATPB), choline chloride (ChCl), N,N-diethylethanolammonium chloride (DAC), and tetra-n-butylammonium bromide (TBAB). The DESs were prepared using different molar ratios of the HBD to the salts. The freezing point of each DES was determined using Differential Scanning Calorimetry (DSC). The physical properties of these DESs, including density, viscosity, conductivity, and surface tension, were investigated as functions of temperature. In addition, the functional groups were analyzed utilizing Fourier transform infrared (FTIR) spectroscopy. It is worth noting that these systems have a wide variety of physical properties, which implies that these DESs would be suitable for diverse applications.
Summarizing the Effect of Acidity and Water Content of Deep Eutectic Solvent-like Mixtures-A Review
Energies, 2022
Deep eutectic solvent-like (DES-like) mixtures re-emerged in green chemistry nineteen years ago and yet have led to a large number of publications covering different research areas and different application industries. DES-like mixtures are considered a special class of green solvents because of their unique properties, such as high solubilization ability, remarkable biocompatibility, low production cost, low volatility, relatively simple synthesis methods, and considerable stability. Several studies have been published that analyze the effect of acidity/alkalinity and water content in DES-like mixtures on their physicochemical properties and behavior. This work summarizes the characterization of green solvents and, subsequently, the influence of various factors on the resulting pH values of green solvent systems. Part of this work describes the influence of water content in DES-like mixtures on their physical and chemical properties. The acidity/alkalinity effect is very important for green solvent applications, and it has the main impact on chemical reactions. As the temperature increases, the pH of DES-like mixtures decreases linearly. The type of hydrogen bond donors has been shown to have an important effect on the acidity of DES-like mixtures. The water content also affects their properties (polarity, solubilization capacity of DES-like mixtures).
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018
The typical organic salt benzyltrimethylammonium bromide (BMAB) was used to greatly enhance the interfacial activity of the traditional anionic surfactant sodium dodecyl benzene sulfonate (SDBS). The additional BMAB caused the obvious reduction of the interfacial tension (IFT) between the SDBS aqueous solution with a low concentration and model oil (V toluene :V n-decane = 1:1). Based on the special SDBS/BMAB intermolecular interaction, we proposed that the synergistic effect between the electrostatic attraction and π-π stacking interaction largely increased the SDBS interfacial concentration, leading to the dramatic IFT reduction. Three organic salts and two surfactants with similar structures, as well as the typical inorganic salt NaCl, were used in control experiments to confirm our speculation. The interaction energies between SDBS molecules and different organic salts were calculated using molecular mechanics to further interpret the mechanism. The salt and temperature tolerances of the SDBS/BMAB system were systematically investigated. Moreover, the availability of the SDBS/ BMAB mixture in brine water/crude oil system was evaluated by the core flooding tests.
The changes upon methanol (MeOH) addition in the structural arrangement of the highly eco-friendly deep eutectic solvent (DES) formed by choline chloride (ChCl) and sesamol in 1:3 molar ratio have been studied by means of attenuated total reflection Fourier transform infrared spectroscopy, small-and wide-angle X-ray scattering (SWAXS), and molecular dynamics simulations. The introduction of MeOH into the DES promotes the increase of the number of Cl−MeOH hydrogen bonds (HBs) through the replacement of sesamol and choline molecules from the chloride anion coordination sphere. This effect does not promote the sesamol−sesamol, choline−choline, and sesamol−choline interactions, which remain as negligible as in the pure DES. Differently, the displaced sesamol and choline molecules are solvated by MeOH, which also forms HBs with other MeOH molecules, so that the system arranges itself to keep the overall amount of HBs maximized. SWAXS measurements show that this mechanism is predominant up to MeOH/DES molar ratios of 20−24, while after this ratio value, the scattering profile is progressively diluted in the cosolvent background and decreases toward the signal of pure MeOH. The ability of MeOH to interplay with all of the DES components produces mixtures with neither segregation of the components at nanoscale lengths nor macroscopic phase separation even for high MeOH contents. These findings have important implications for application purposes since the understanding of the pseudophase aggregates formed by a DES with a dispersing cosolvent can help in addressing an efficient extraction procedure.