Dispersion Stability of CeO2-Coated SiO2 Composite Particles and Dispersion Mechanism

Abstract

CeO2-coated SiO2 composite particles with Core-shell structure were successfully prepared, and the dispersion behavior in water was investigated under different pH values, ion-surfactant types and contents by means of Zeta potential and absorbance. Potential energy between particles in suspension was precisely evaluated via DLVO theory, by which the dispersion mechanism of SiO2/CeO2 core-shell composite particles was analyzed, combined with adsorption isotherms and infrared (IR) spectra measurements. The results showed that Zeta potential had a quite coherence with dispersion stability which was greatly affected by pH value, surfactant types and contents. The particles retained dispersion balance by adjusting pH value of suspension to increase electrostatic repulsion energy between particles, and the dispersion stability of suspension was preferable under pH value being 10 around. The adsorption of composite particles was physical adsorption, maximum amount of which reached 31.7 mg/g for CTAB and 19.23 mg/g for SDBS in certain range of concentration. The adding of surfactant SDBS proper dosage improved dispersion behavior greatly, and the adsorption layer of SDBS weakened the Van der Waals attractive energy dramatically and enhanced the absolute value of Zeta potential meanwhile, therefore, heightening of the electrostatic repulsion energy, then, leading to the improvement of dispersion stability of suspension. For the dispersion stability of suspension, SDBS was preferable to CTAB.