Modeling systems containing alkanolamines with the CPA equation of state

An association model, the cubic-plus-association (CPA) equation of state (EoS), is applied for the first time to a class of multifunctional compounds (alkanolamines). Three alkanolamines of practical and scientific significance are considered; monoethanolamine (MEA), diethanolamine (DEA), and methyl diethanolamine (MDEA). Vapor pressures and liquid densities, as well as solvatochromic parameters and mixture liquid-liquid equilibria (LLE) data with alkanes are used to estimate the five pure-compound parameters. Vapor-liquid equilibria (VLE) calculations for cross-associating mixtures, especially those with water, are used in the validation of the parameters. The influence on the results of the association scheme, cross-association combining rules, interaction parameters, and the data available is discussed also, in connection with other aqueous cross-associating mixtures previously studied using the CPA equation of state (alcohols, amines, and glycols).