Thermophysical properties of imidazolium tricyanomethanide ionic liquids: experiments and molecular simulation

Abstract

The low-viscous tricyanomethanide ([TCM]À )-based ionic liquids (ILs) are gaining increasing interest as attractive fluids for a variety of industrial applications. The thermophysical properties (density, viscosity, surface tension, electrical conductivity and self-diffusion coefficient) of the 1-alkyl-3-methylimidazolium tricyanomethanide [C n mim][TCM] (n = 2, 4 and 6-8) IL series were experimentally measured over the temperature range from 288 to 363 K. Moreover, a classical force field optimized for the imidazolium-based[TCM] À ILs was used to calculate their thermodynamic, structural and transport properties (density, surface tension, self-diffusion coefficients, viscosity) in the temperature range from 300 to 366 K. The predictions were directly compared against the experimental measurements. The effects of anion and alkyl chain length on the structure and thermophysical properties have been evaluated. In cyano-based ILs, the density decreases with increasing molar mass, in contrast to the behavior of the fluorinated anions, being in agreement with the literature. The contribution per -CH 2 -group to the increase of the viscosity presents the following sequence: The experimentally determined self-diffusion coefficients of the cations are in good agreement with the molecular simulation predictions, in which a decrease of the self-diffusion of the cations with increasing alkyl chain length is observed with a simultaneous increase in viscosity and for the longer alkyl lengths the anion becomes more mobile than the cation.

Novel pressure and temperature swing processes for CO2 capture using low viscosity ionic liquids

“…In our previous work on thermophysical properties of tricyanomethanide-based ILs it was concluded that ion association in its different forms (e.g. ion-ion correlations and aggregates) could be responsible for the decrease in number of effective charge carriers and hence lower conductivity [11]. The vapor phase non-idealities are modeled using the Redlich-Kwong (RK) EoS.…”

“…The thermophysical properties of [C 6 mim] [TCM] and the CO 2 solubilities are reported in our previous works. [11,14] The process simulations are solved in the equation-oriented (EO) mode. The EO strategy solves mass and energy balances for the entire flowsheet simultaneously avoiding nested convergence loops and is more effective for processes containing recycle streams and design specifications than the sequential modular mode.…”

Synthesis and Physical and Thermodynamic Properties of Lactic Acid and Malic Acid-Based Natural Deep Eutectic Solvents

“…Just like for the ILs in the DES, the internal resistance of a fluid at shear stress and intermolecular interactions are the main influence of the viscosity values obtained. DES and Iĺs also share the feature of presenting higher viscosities than other molecular solvents and their differences are associated with hydrogen interactions. − …”

A Generalized Machine Learning Model for Predicting Ionic Conductivity for Ionic Liquids

“…Based on the SHAP value, it is clear that a high value of IPC (denoted by the red color) negatively impacts the output. As the IPC descriptor is related to the content of the molecule, higher values of the feature delineates bulky cations, for example those containing long alkyl chains, slowing down the dynamics of the system 88,89 . Furthermore, Figure S10 (a) also shows the relation between the IPC descriptor of the cation and experimental ionic conductivity at 298.15 K, demonstrating the effect of the descriptor on the ionic conductivity; there is a general trend of decreasing ionic conductivity with IPC as revealed by the SHAP analysis.…”