Acoustic and electroacoustic spectroscopic determination of the critical coagulation concentration for the aggregation of fumed silica

Abstract

Acoustic and electroacoustic spectroscopy were use to model varying concentrations of NH4Cl in a 25 wt% fumed silica suspension for interpretation and visualization of the critical coagulation concentration (CCC) needed to induce coagulation of the suspension. The acoustic data indicates a range for the CCC that agrees with Derjaguin and Landau, Verwey and Overbeek theory and experimental results found in literature. The electroacoustic data suggest a power law relationship between NH4Cl concentration and changes in the colloidal vibrational current, and predicts that 0.4M is the CCC for NH4Cl in a fumed silica suspension.