Prediction of Hydrate Formation for the Systems Containing Single and Mixed Electrolyte Solutions

In this work the effect of electrolytes on hydrate formation was investigated. To do so, a new model was used in predicting the hydrate formation conditions in presence of both single and mixed electrolyte solutions. The new model is based on the van der Waals - Platteeuw hydrate equation of state. In order to evaluate the values for the activity of water in electrolyte solutions the simplified version of the Ghotbi-Vera Mean Spherical Approximation (SGV-MSA) model was used. According to the SGV-MSA model the ions in the solutions are considered as charged hard spheres with different sizes. The values of the parameters for the SGV-MSA model are independent of temperature and depend only on the nature as well as concentration of electrolytes studied in this work. These parameters were obtained using the experimental data for the mean ionic activity coefficient of the single electrolyte solutions at 298.15 K. In the case of the mixed electrolyte solutions a new mixing rule was introduced to obtain the activity of water in aqueous electrolyte solutions. The results show that the proposed model can predict the hydrate formation for the systems containing single or mixed electrolyte solutions with good accuracy compared to the experimental data available in the literature. In addition, the results obtained from the proposed model were favorably compared with those obtained from the previously used models.