Investigation of the Effect of Temperature and pH on the Solubility Limits of Major Salts in Seawater

In this paper, results for the experimental study of the solubility limits of scaling salts such as CaCl ₂ , MgCl ₂ , KCl, Na ₂ SO ₄ and NaHCO ₃ are conducted in brine solutions, real seawater, and artificial seawater at different pH levels. For this purpose, sodium chloride solutions are prepared at different concentrations, and artificial seawater samples are prepared in a manner to get closer to the case of seawater in Kuwait. Obtained results show significant “salting-in” and/or “salting-out” effects: the solubility is reduced dramatically by more than 95% when increasing the concentration of the brine. Another result was that the solution containing 25% sodium chloride cannot be considered equivalent to real seawater when discussing salt solubility, where the solubility of salts in real seawater is found to be 15% for CaCl ₂ and distilled water for MgCl ₂ . This means that the accuracy of predictions of scaling potential in real systems is not ensured when using a single-concentration NaCl simulant. On the other hand, the effect of changing pH levels was limited to the cases of calcium chloride and sodium chloride, while the other salts have shown slight sensitivity to changes in pH levels. This behavior is discussed and is related to the ionic strength value.