Experimental measurements and thermodynamic modeling of freezing points in the systems Na+//Cl-,SO42-, NO3--H2O and Na+, K+//Cl- , NO3--H2O

The freezing (eutectic) point data at various water concentrations (95, 85 and 75 wt%) of different solution composition in systems Na+//Cl-, SO42-, NO3--H2O and Na+, K+//Cl-, NO3--H2O were studied by cooling curves method. Based on the experimental data, the freezing (eutectic) temperature-solution composition diagrams were constructed, which showed that the freezing point decreased with decreasing water content independent of kinds of salts and also influenced by the solubility of salt. The freezing (eutectic) point of the systems was carried out with extended UNIQUAC model. We compared the performance of the model with the data obtained by the experimental, the present results confirm the model as a good choice to calculate the freezing point considering the processing conditions that no large amount of salt precipitated from the solution. In general, the model accuracy was satisfactory. The results better revealed the relationship between the freezing point and the salt/water content in brine at low temperature, and can offer fundamental data to provide important theoretical guidance for the research of brine cryogenic freezing technology. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The experimental results show that the freezing point decreases with decreasing water content and is influenced by salt solubility. The extended UNIQUAC model can accurately calculate the freezing point and predict the precipitation of salt from the solution under processing conditions.