Ali Haghtalab - Chemical Engineering Department, Tarbiat Modares University
Kiana Peyvandi - Chemical Engineering Department, Tarbiat Modares University

The UNIQUAC-NRF excess Gibbs function is applied for calculation of the mean activity coefficient of the binary electrolyte solutions. The excess Gibbs energy of the model consists of the Pitzer-Debye–Hückel equation, describing the long-range electrostatic contribution and the extended UNIQUAC-NRF model to account for the short-range contributions. With two adjustable parameters per electrolyte, this model is applied to correlation the mean activity coefficients of more than 30 binary aqueous electrolyte solutions at 25 oC. The results are compared with various local composition models such as the electrolyte-NRTL, electrolyte NRF-Wilson, electrolyte-NRTL-NRF, N-Wilson-NRF,Electrolyte-UNIQUAC-NRF models. The comparison of the results with experiment demonstrates that this model can correlate the experimental data accurately.

Local composition, Activity coefficient, Excess Gibbs energy, UNIQUAC-NRF, Electrolyte