A new electrolyte cubic plus association equation of state for strong electrolyte solutions

In this work, we propose to develop the Cubic Plus Association (CPA) equation of state (EoS) for strong electrolyte solutions (eCPA EOS). The non-electrolyte contribution of the electrolyte CPA equation of state is composed of the Peng-Robinson (PR) EoS and the association term based on Wertheim’s theory. The Born term was used to take into account the effect of the ionic charge, and the explicit version of Mean Spherical Approximation (MSA) theory is used to consider the long range interactions between permanent charges. The presented model has five adjustable parameters per each salt that are optimized by correlation of the mean ionic activity coefficients of more than 47 binary aqueous electrolyte solutions at 298 K and 1 bar. The obtained results disclosed that the model is a powerful tool for representation of the activity coefficients of aqueous electrolyte solutions.