Liquid-Liquid Equilibria Data of N-Methyl-2-Hydroxyethyl Ammonium Alkylates With Butanol+water and Pentanol+water at 293.15K, 313.15K and 333.15K

Abstract

Ionic liquids (ILs) are organic salts with low volatility and have different applications including organic synthesis, separation and extraction processes, fuel cell electrolyte, surfactants, among others. Protic ILs based on the N-methyl-2-hydroxyethyl ammonium cation and short chain carboxylic anions have simple synthesis and purification. However, as new substances few data are available for their thermodynamic properties and phase equilibria. In order to investigate the partition of these substances in alcohol-water, liquid-liquid equilibria data were determined experimentally for three ionic liquids (formed by the cation N-methyl-2-hydroxyethyl ammonium (m-2HEA) and the anions propionate (Pr), butanoate (B) and pentanoate (P)) with butanol and pentanol, at three different temperatures: 293.15K, 313.15K and 333.15K. The binodal curves are obtained by the turbidity method with gravimetric determination of all the components, curves are fitted using the Merchuk method. The tie-lines are also gravimetrically determined. The results confirm the high hydrophilicity of these ionic liquids, with partition coefficients of water-butanol and water-pentanol lower than 1. Data were correlated with UNIFAC.

Liquid–Liquid Equilibria Data of Protic Ionic Liquid (Ethyl-2-hydroxyethylammonium Propionate, Diethylammonium Propionate, or Butylammonium Propionate) with 1-Butanol + Water at 298.15 K

“…The binodal curves of the systems studied are represented in Figure 1. The uncertainties in the values of the mass fractions of each system component can be determined by calculating the uncertainty of adding an extra drop of water or alcohol to the system during the determination of the binodal through the cloud point method, according to the procedure described by Amorim et al 31 These values were used to calculate the combined uncertainty in each phase.…”

“…An excellent review on other systems containing AILs + 1-butanol + water was presented by Kubiczek and Kaminśki. 30 Amorin et al 31 investigated the partition of three protic ionic liquids (formed by the cation N-methyl-2-hydroxyethylammonium (m-2HEA) and the anions propionate (Pr), butanoate (B), and pentanoate (P)) in alcohol−water. These liquid−liquid equilibria data confirmed the high hydrophilicity of these ionic liquids, with partition coefficients of water−butanol and water−pentanol lower than 1.…”

“…Due to the importance of research involving PILs with 1butanol and given the scarcity of liquid−liquid equilibrium data on those compounds as well as their influence on hydrophobicity/hydrophilicity, this work represents a continuation of investigations of our research group 31 aimed to investigate equilibrium data of the systems 1-butanol + water + ethyl-2-hydroxyethylammonium propionate [E2HEA][Pr], 1butanol + water + diethylammonium propionate [DEA][Pr], and 1-butanol + water + butylammonium propionate [BA][Pr] at 298.15 K and atmospheric pressure, as well as to investigate the effect of the cation chain and the position of the nitrogen atom in the cation chain on the binodal curve of the system and perform the thermodynamic modeling of the data using the Non-Random Two-Liquid (NRTL) 32 and UNIversal-QUAsiChemical (UNIQUAC) 33 9 with slight modifications. In this process, the base is poured in a three-way reactor and the acid is slowly dripped into the reactor using a buret coupled to a reflux condenser under constant mechanical stirring and using an inert nitrogen atmosphere.…”

Predictive molecular thermodynamic models for ionic liquids

“…The UNIFAC model has been widely employed by researchers as valuable tools for predicting the activity coefficients of mixed systems with ILs or conventional solvents 7,8 . At present, The UNIFAC model has become one of the most widely applied thermodynamic models for quantitatively predicting thermodynamic properties, such as GLE, VLE, and LLE of the systems containing ILs 9–13 . The original UNIFAC equation describing the activity coefficient is given by where is the combinatorial term contribution to activity coefficient, which depends on the molecular size and shape and reflects the entropy effect of the system, and is the residual term contribution, the magnitude of which depends on intermolecular interactions in mixed systems.…”

“…7,8 At present, The UNIFAC model has become one of the most widely applied thermodynamic models for quantitatively predicting thermodynamic properties, such as GLE, VLE, and LLE of the systems containing ILs. [9][10][11][12][13] The original UNIFAC equation describing the activity coefficient is given by…”