Role of surfactants on the stability of nano-zinc oxide dispersions

Nowadays, stable colloidal dispersions with ultra-fine or nanosized particles are getting importance due to their higher activity. In this article, methods for the preparation of stable aqueous dispersions of zinc oxide (ZnO) were discussed. The quality of the dispersion was improved by capping with different types of surfactants say non-ionic, cationic, and anionic. Accordingly, Triton X 100, polyethylene glycol-6000 (both non-ionic), cetyltrimethylammonium bromide (cationic), and sodium dodecyl sulfate (anionic) were selected for the study. Effect of these surfactants on particle size of ZnO was followed through dynamic light scattering (DLS) studies and zeta potential measurements. Particle size analysis and zeta potential measurement indicated that ZnO dispersions stabilized with anionic surfactants (sodium dodecyl sulfate) showed better stability. Further, the effect of ultrasonication on particle size distribution was examined and optimized.