Investigation of the performance of e-CPA for a wide range of properties for aqueous NaCl solutions
Martin Due Olsen, Georgios M. Kontogeorgis, Xiaodong Liang, Nicolas von Solms
Abstract
In the past years a number of parametrizations of the e-CPA model have been published. The e-CPA model has shown promising results for electrolyte solution properties. Several of these parametrizations have been investigated in this work for a wide range of properties for aqueous NaCl solutions. Previously published e-CPA parameter sets, which made use of a volume translation to be able to correlate the density, were found to show some inconsistencies, including a suboptimal temperature dependency of the density. A new parametrization is proposed, that is able to reproduce the density without the need of a volume translation, and without loss of accuracy of other properties. This parameter set, together with the previously published parameter sets were tested for their predictability of single ion activity coefficients, and it was found that all of them are incapable of getting the correct trend regarding which ion that is above the mean and which is below. An alternative parametrization has, however been shown to be able to change this without much loss of accuracy with respect to the other properties.