Determination and modeling for the solubility of Na2MoO4·2H2O in the (Na+ + MoO42− + SO42−) system

• The solubility of Na2MoO4·2H2O in Na+ + MoO42− + SO42− system was performed.
• The new model was established via regressing the published and the determined data.
• The Pitzer parameter and the solubility product constant of the salts in solution were calculated.
• The model was applied to estimate the solubility of the sodium molybdate in various conditions.

The solubility of Na2MoO4·2H2O in (Na+ + MoO42− + SO42−) system was carried out using a dynamic method within the temperature range from 293.15 K to 343.15 K. The new model was established via regression of the published and the determined values to predict the solubility. From the results, the solubility of sodium molybdate increases with the temperature increase, however, it decreases with the increasing concentration of sodium sulfate. The Pitzer parameters and the solubility product constant of sodium sulfate and sodium molybdate in aqueous solution were obtained using the literature data. The solubilities of the sodium molybdate in the sodium sulfate solution as well as the thermodynamic parameters were calculated based on the experimental values obtained. The new model was also applied to estimate the solubility of the sodium molybdate under various conditions. The calculated values agree well with the experiment results.