Viscosity of Choline Chloride-Based Deep Eutectic Solvents: Experiments and Modeling

Abstract

Deep eutectic solvents (DES) have emerged as promising 'green' solvents, but their successful industrial application requires relatively low viscosity. DES prepared from choline chloride and glycols offer such possibility. Viscosity and density are reported for a number of DES obtained by mixing choline chloride and a glycol (ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol). The measurements were performed at 101.3 kPa, at temperatures between 293.15 K and 333.15 K, and for different mole ratios of the glycol and choline chloride. The viscosity was measured with a capillary viscometer, while the density was measured by means of a vibrating U-tube densimeter. The density and viscosity data have expanded relative uncertainties of 0.2% and 2.0%, respectively, with a coverage factor of 2. The viscosity of pure glycols was modeled using the extended hard-sphere (EHS) model that has its basis in kinetic theory and the molecular description of the fluid. Each DES was treated as a binary mixture, and the EHS model was used, with a mole average mixing rule, to calculate its viscosity. The measured DES viscosity data were represented with the average absolute deviation of 1.4% and a maximum deviation of 7%.

Switchable deep eutectic solvent driven micellar extractive fermentation of ultrapure fibrin digesting enzyme from Bacillus subtilis

“…This is because of the reduction in noncovalent interactions between HBA and HBD in the SDES at higher temperatures, decreasing the surface tension of the mixture (33). Similar to the investigation performed by Gajardo et al, the molecular weight of the corresponding HBA and HBD was observed to have a substantial influence even on the viscosity of the mixture (34). Surfactants (Tween 80) with high molecular weights associate more strongly with quaternary ammonium salts (0.583 Pa.s), making the resultant SDES more viscous than their low molecular weight counterparts (Triton X 100) (0.327 Pa.s).…”

23Na NMR T1 relaxation measurements as a probe for diffusion and dynamics of sodium ions in salt–glycerol mixtures

“…Deep eutectic solvents (DESs) are a class of ionic liquids, which in the last two decades have been used in areas such as materials preparation, 1 gas-separation, 2 electrochemistry, 3 biomass valorization 4 and catalysis. 5 DES properties have been extensively studied focusing on the freezing point, 6 vapour pressure, 7 conductivity, 8 viscosity 9 and more recently diffusion. 10,11 The knowledge of such properties plays a crucial role in applications and determines the suitability of a particular DES for a specific application.…”

Influence of the Molecular Structure of Constituents and Liquid Phase Non-Ideality on the Viscosity of Deep Eutectic Solvents

“…Molecules 2021, 26, x FOR PEER REVIEW 2 of 13 studied and discussed by treating eutectic mixtures of constituents with a fixed composition as a pseudo-compound without considering the effects of the constituents or their molar ratio [11,15,[18][19][20][21]. This study examined how the molecular structure of the constituents and the intermolecular interactions in the liquid phase influence the viscosity of eutectic systems.…”

“…DES have a considerably higher viscosity than conventional solvents [ 11 ]. High viscosity increases the solvent flow, heat, and mass transfer resistance [ 12 ].…”

“…However, the existing data are only for mixtures at a specific molar ratio, usually at or close to the eutectic point. In most of the literature, the viscosity of DES was studied and discussed by treating eutectic mixtures of constituents with a fixed composition as a pseudo-compound without considering the effects of the constituents or their molar ratio [ 11 , 15 , 18 , 19 , 20 , 21 ].…”