Liquid-liquid equilibria of ternary mixtures containing Aniline + Toluene + water at elevated temperatures: measurements and correlation

ABSTRACT

Liquid-liquid equilibrium (LLE) data for the ternary system, Aniline + Toluene + Water, was measured at different temperatures of 298.15 K, 313.15 K and 323.15 K under atmospheric pressure with the help of High-Performance Liquid Chromatography (HPLC) analysis and Karl-Fischer technique. The efficiency of Toluene to extract Aniline from aqueous phase was then quantified in terms of the distribution coefficient and separation factor based on the tie line data. The system showed very good separation ability quantified in terms of high values of distribution factor (average around 7) and separation factors (as high as 1000). The experimental tie line data was verified by Hand and Othmer-Tobias equations. The LLE data was also correlated using NRTL and UNIQUAC models and both of them were able to represent the behavior of the system accurately when tested against experimental results. Toluene has been demonstrated to be very efficient to extract Aniline from reaction mixture, which is typically a by-product in hydrogenation of nitrobenzene, a process commercially used to produce p-Aminophenol in industry.

KEYWORDS:

• LLE
• Aniline
• Toluene
• Tie line
• NRTL
• UNIQUAC

Acknowledgments

Authors would like to acknowledge the financial support from Council of Scientific and Industrial Research (CSIR).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Statement of novelty

The main objective of this paper is to generate the liquid-liquid equilibrium data between the temperatures 298.15 K and 333.15 K. From the literature, it has been found that no data is available at more realistic temperature range in between 298.15 K and 333.15 K, which can also be applied in effluent recovery operations based on the ambient conditions. In this work we have focused on the above temperature range and data has been quantified for the temperatures as 298.15 K, 313.15 K and 323.15 K for the ternary system. Apart from generating data, we also aimed to study the liquid-liquid equilibria for the ternary system Aniline + Toluene + Water and assess the capacity of toluene to extract aniline from dilute aqueous solutions.

The experimental data has been correlated by NRTL and UNIQUAC activity coefficient models and the binary interaction parameters given can be directly used to model the LLE system. It was clearly elucidated that toluene can be used as a solvent to extract aniline from aqueous solutions.