Gregor Trefalt1, István Szilágyi1, Tamas Oncsik1, Amin Sadeghpour1, Michal Borkovec2
1Department of Inorganic and Analytical Chemistry, University of Geneva, Sciences II, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
2Department of Inorganic and Analytical Chemistry University of Geneva Sciences II 30, Quai Ernest-Ansermet CH-1211 Geneva
Tóm tắt
The present article reviews recent progress in the measurement of aggregation rates in colloidal suspensions by light scattering. Time-resolved light scattering offers the possibility to measure absolute aggregation rate constants for homoaggregation as well as heteroaggregation processes.
We further discuss the typical concentration dependencies of the aggregation rate constants on additives. Addition of simple salts containing monovalent counterions leads to screening of the electrostatic repulsion of the charged particles and a transition from slow to rapid aggregation. Addition
of salts containing multivalent counterions may lead to a charge reversal, which results in a sequence of two instability regions. Heteroaggregation rates between oppositely charged particles decrease with increasing salt level. This decrease is caused by screening of the electrostatic attraction between these particles.
