Heat Capacity of Aqueous Mixtures of Monoethanolamine with N-Methyldiethanolamine

Abstract

Heat capacities of aqueous mixtures of monoethanolamine with N-methyldiethanolamine were measured from 30 to 80 °C with a differential scanning calorimeter (DSC). The binary systems studied were N-methyldiethanolamine + water and monoethanolamine + N-methyldiethanolamine. For mole fractions of water ranging from 0.2 to 0.8, 16 concentrations of the monoethanolamine + N-methyldiethanolamine + water systems were studied. The estimated uncertainty of the measured heat capacities is ±2% including the effect of up to 1% impurities in a substance. An excess molar heat capacity expression using the Redlich−Kister equation for the composition dependence is used to represent the measured Cp of aqueous alkanolamine solutions. The overall average absolute percentage deviation of the calculation of the molar heat capacity for a total of 176 data points for the monoethanolamine + N-methyldiethanolamine + water system is 0.5%. The heat capacities of aqueous mixtures of monoethanolamine with N-methyldiethanolamine prese...