Herman David, Walz John Y
†Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States.
‡Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky 40506, United States.
Langmuir. 2015 May 5;31(17):4844-52. doi: 10.1021/acs.langmuir.5b00745. Epub 2015 Apr 21.
The stability behavior of dispersions of weakly charged silica colloids was studied in the presence of highly charged metal oxide nanoparticles. Experiments were performed using 5 nm zirconia as well as 10 nm alumina nanoparticles (both positively charged), which were added to 0.1 vol % suspensions of 1.0 μm silica microparticles at the silica IEP. Both types of nanoparticles provided effective stabilization of the silica; i.e., the silica suspensions were stabilized for longer than the observation period (greater than 12 h). Stability was observed at zirconia concentrations as low as 10(-4) vol % and at an alumina concentration of 10(-2) vol %. The nanoparticles adsorbed onto the microparticle surfaces (confirmed via SEM imaging), which increased the zeta-potential of the silica. Force profile measurements performed with colloidal probe atomic force microscopy showed that the adsorption was effectively irreversible.
