Viscosity of the Silicic Acid Gel-Forming Mixtures

Abstract

Prasad and Hattiangadi1 have shown that when solutions of sodium silicate and of acids (or acidic ammonium acetate) are mixed together, crystalloidal silicic acid first formed goes over to the colloidal state and then follows the coagulation of the colloid solution by the electrolytes present in the mixture. Prakash and Dhar2 have shown that the viscosity measurements

Colloid Process Engineering

“…16b) [104]. The origin of the finite life time of the bonds between the colloids in this case seemed to lie in the finite solubility of silica at the pH (about 11) of the sample [108].…”

Ionic Exchange in Relation to Hydrogen-ion Concentration and Rigidity of Silicic Acid Jellies

“…The results of the present study are believed to afford an explanation of several classical observations on silicic acid jellies. It is well known that neutral or slightly alkaline gels have the minimum time of set (5) and begin to synerize more rapidly, although acid gels finally exude a greater volume of liquid (2); that viscosity increases more rapidly in alkaline gels at first, but later the viscosity of acid gels increases at an even greater rate (7); and that the rapid rise in extinction coefficients occurs earlier in alkaline than in acid gels (6). Possibly these phenomena depend on the fact that neutral and alkaline gels are drifting away from the pH zone most favorable for hardening, while acid gels are drifting into the suitable range.…”