Aggregation stability of monodisperse silica sol in NaCl and BaCl2 solutions

摘要

The aggregation kinetics of a monodisperse silica sol with an average particle size of 220 nm and particle number concentration n (0) = 10(10) cm(-3) in aqueous solutions of NaCl and BaCl2 at pH 6.2 is studied with the help of photometry. The stability of diluted sols (n (0) = 10(7) cm(-3)) in NaCl solutions is investigated by the direct method of flow ultramicroscopy. The results obtained are analyzed in terms of the theories of the Hogg-Yang barrierless coagulation and the Muller reversible coagulation. It is established that the slow coagulation of both concentrated and diluted sols proceeds via the barrierless mechanism in the secondary potential minimum.