Ion-specific effect on the gelation kinetics of concentrated colloidal silica suspensions

J Colloid Interface Sci. 2003 Jul 15;263(2):522-7. doi: 10.1016/s0021-9797(03)00397-7.

Abstract

The comparative gelation kinetics of concentrated colloidal silica suspensions at pH 9.8 has been studied in the presence of two different counterions, ammonium as a representative structure-breaker ion and sodium as a representative structure-maker ion. For the same ionic strength of 0.45 M, the experimental results have indicated a pronounced effect of the ion-specificity on the aggregation kinetics and on the microstructure of the gelified networks at the sol-gel transition. This was ascribed to the significant difference of the critical coagulation concentration value in the presence of the two electrolytes.