Thermodynamic Study of Binary Mixtures of 1-Butyl-1-methylpyrrolidinium Dicyanamide Ionic Liquid with Molecular Solvents: New Experimental Data and Modeling with PC-SAFT Equation of State

Abstract

This work is concerned with thermodynamic properties of binary mixtures composed of 1-butyl-1-methylpyrrolidinium dicyanamide ionic liquid (IL) and the following molecular solvents: n-heptane, benzene, toluene, ethylbenzene, thiophene, 1-butanol, 1-hexanol, and 1-octanol. This is the very first time when experimental data on liquid-liquid equilibrium (LLE) phase diagrams and excess enthalpies of mixing (H(E)) for these systems are reported. An impact of the molecular solvent structure on LLE and H(E) is discussed. Furthermore, modeling of the properties under study is presented by using perturbed-chain statistical associating fluid theory (PC-SAFT). The equation of state is used in purely predictive and semipredictive mode. The latter one involves temperature-dependent binary corrections to combining rules employed in the PC-SAFT model determined on the basis of infinite dilution activity coefficients. The results shown indicate that such an approach can serve as an interesting modern thermodynamic tool for representation of thermodynamic data for complex ILs-based systems.

Measurements and equation-of-state modelling of thermodynamic properties of binary mixtures of 1-butyl-1-methylpyrrolidinium tetracyanoborate ionic liquid with molecular compounds

“…In this contribution we use the same modeling strategy as in our previous works on modelling of ILs systems [25,26,28,30,34]. ILs are pictured as composed of neutral ion pairs, while the interactions between ions due to Coulombic forces are treated as strong specific interactions.…”

“…Recently, we have employed symmetric schemes for ILs based on different kinds of anions, including bistriflamide [28,30], dicyanamide [31,32,34] and ethylsulfate [33]. We have fixed the number of donor and acceptor sites so that it corresponded with the number of lone pairs on anion.…”

“…In previous contributions, thermodynamic studies on dicyanoamides [34], tricyanomethanides [54][55][56] and tetracyanoborates [56][57][58] [TCB] + benzene, thiophene, or methanol, or ethanol, or 1-propanol, or 1-butanol} at T ¼ 298:15 K. This paper also reports PC-SAFT modelling of the considered properties. Additionally, LLE in ternary system {[BMPYR][TCB] + thiophene + n-heptane} is calculated with the proposed parameters and molecular/association schemes and compared previously published experimental data [56].…”

“…Lattice theory-based models like non-random hydrogen-bond (NRHB) [24][25][26], ''cubic + association'' (CPA) model [27] and statistical associating fluid theory (SAFT) are the most widely studied ones. In particular, perturbed-chain SAFT (PC-SAFT) [25,26,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42], tPC-PSAFT [43][44][45] and soft-SAFT [46][47][48][49][50][51][52][53] have attracted most of the attention of community concerned with EoS modelling of ILs-based systems.…”

“…We used this EoS to reproduce phase equilibria (including VLE, LLE and SLE) as well as to predict c 1 and H E for a great diversity of binary systems [25,26,[28][29][30][31][32]34]. Recently, we published two papers [31,32] on PC-SAFT calculations of sugars solubility in ILs.…”