Determination and Modeling of the Solubility of Na2SiO3•9H2O in the NaCl-KCl-H2O System

The solubilities of sodium metasilicate nonahydrate (Na2SiO3 center dot 9H(2)O) in the NaCl-H2O, KCl-H2O, and NaCl-KCl-H2O systems were determined at the temperature range from (288.15 to 308.15) K using a dynamic method. The results show that the solubility of Na2SiO3 center dot 9H(2)O decreases first and then levels off with increasing concentration of NaCl from (0.17 to 4.50) mol.kg(-1), whereas the solubility in the Na2SiO3 center dot 9H(2)O(s)-saturated KCl solution increases slightly with the addition of KCl in the concentration range from (0.20 to 3.10) mol.kg(-1). The Na2SiO3 center dot 9H(2)O solubilities in all cases investigated were found to increase with the temperature increment. A new chemical model for the solubility has been established by the regression of the experimental solubilities data in the NaCl-H2O system to obtain the parameters of the Bromley-Zemaitis model. These newly obtained model parameters were applied to well predict the Na2SiO3 center dot 9H(2)O solubility in two other systems, namely, the KCl-H2O and the NaCl-KCl-H2O systems, without parametrization with an average relative deviation of 1.4 % and 4.1 %, respectively.