Boiling point elevation of aqueous solutions of ionic liquids derived from diethanolamine base and carboxylic acids

• Protic ionic liquids were synthetized from diethanolamine base and different carboxylic acids.
• The elevation of the boiling point of the water was measured for aqueous solutions of the different ionic liquids.
• The anion size was shown to affect the boiling temperature.
• The (vapor + liquid) equilibrium data were modeled using conventional NRTL model.

This work reports experimental data and mathematical modeling of the boiling-point elevation (BPE) of aqueous solutions of ionic liquids (IL) derived from diethanolamine (DEOA) of cationic base and acetic, propionic, butanoic and pentanoic acids. Experimental boiling points were obtained for solutions of the four ILs in different water mole fractions (0.32 to 1.00) and pressures (12.1 to 91.8) kPa. Since ILs are compounds with very low vapor pressure, BPE calculations were performed employing the isofugacity conditions of water in liquid and vapor phase, in which the NRTL model was used to take into account the non-ideality of these liquid mixtures. The proposed model presented a satisfactory agreement with the experimental data, with a Mean Absolute Error of T = 1.43 K between calculated and all experimental values.