In this work, the nonelectrolyte Wilson-NRF model has been modified and a new model composed of a modified nonelectrolyte Wilson-NRF (m-Wilson-NRF) equation and the Pitzer-Debye-Hückel equation has been used to represent thermodynamics properties of strong and weak electrolyte solutions. In the first attempt, the present model is applied to correlate activity coefficients of various aqueous solutions of salt at 25 °C and 1 bar as strong electrolyte systems. Also, the osmotic coefficients of the binary and ternary electrolyte solutions are well predicted using the present model. In following, as weak electrolyte systems the solubility of acid gases such as CO2 and H2S in aqueous N-methyldiethanolamine (MDEA) solutions have been represented by the new model in a wide range of temperature, MDEA concentration and partial pressures of acid gases. Comparisons between the results of the new model with other electrolyte models confirm the good capability of the new equation for strong and weak electrolyte solutions.

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