Physical properties of aqueous mixtures of N-methyldiethanolamine (MDEA) and ionic liquids

In the present study, experiments have been conducted to measure the surface tension and heat capacity of aqueous mixtures of N-methyldiethanolamine (MDEA) and ionic liquids (ILs) at atmospheric pressure. Two types of ILs, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4] and 1-butyl-3-methyl-imidazolium dicyanamide [bmim][DCA]) were used in these experiments. The surface tension was found to decrease with increasing temperature and ionic liquid concentration. Furthermore, the heat capacity of the mixtures increases with decreasing ionic-liquid concentration and increasing temperature. Linear equations were used to correlate the measured surface tension values, quadratic equations were applied to correlate the heat capacity at different compositions and temperatures.