Effect of Chloride Salts and Bicarbonate on Solubility of CaSO4 in Aqueous Solutions at 37°C

Abstract

In the study, we present the results of thermodynamic simulation of CaSO4 water-salt systems containing Ca 2+ , Mg 2+ , Na + , K + and HCO - 3 at 37°C. The results showed that the solubility of CaSO phase increased with increasing NaCl as wells as KCl concentration in the range of 0.0 to 2.0 M and 0.0 to 1.0 M, respectively. Remarkably, enhanced effect of MgCl 2 on the solubility of CaSO 4 phase was much larger than that of KCl or NaCl. The only exception was CaCl 2 , which was found to reduce solubility value of CaSO4 in aqueous solution at 37°C with the increase of CaCl 2 concentration. Also, the solubility of CaSO4 phase in mixed salt solutions was investigated at 37°C. The common ion effect was the main factor on the solubility of CaSO 4 in the mixed salts solution. Furthermore, CaSO 4 solubility was reduced by small amounts of NaHCO 3 in mixed solutions. These studies are of relevance in the estimating the changes of various salts in blood plasma and production of salt with low impurities of Ca2+ and SO 4 2- ions, as well as estimating oceanic-containing CaSO 4 uptake of CO 2 .