THERMODYNAMIC MODEL OF REDISSOLUTION OF CALCIUM SULFONATE PRECIPITATES IN NaCl SOLUTIONS.

Precipitation phenomenon in the sodium dodecylsulfonate system has been investigated in this study at various levels of CaCl//2 in a wide range of NaCl concentrations. While precipitation is found to be caused by the formation of calcium disulfonate, redissolution of the precipitate at high sulfonate levels is found to occur only when micelles are formed. Correlation of the effect of ionic strength on the redissolution with that of it on micellization supports the proposed mechanism of micellar redissolution. A thermodynamic model capable of predicting the nature and concentrations of various species in solutions has been developed. The model was tested against different sets of experimental data and was found to predict the system behavior satisfactorily.