Fabrication of Silica Microspheres Containing TiO₂ or Aluminum Zinc Oxide Nanoparticles via Self-Assembly:...

In this study, silica micro-particles containing titania (TiO₂) or aluminum zinc oxide (AZO) nanopar-ticles were synthesized using emulsion droplets as micro-reactors, for water purification application via photocatalytic decomposition of organic dyes. Towards this end, aqueous silicic acid solution has been emulsified with aqueous dispersion of TiO₂ or AZO nanoparticles in a continuous oil phase to form tiny droplets, followed by subsequent self-assembly of the droplets via evaporation. The resulting composite microparticles were controlled to obtain a spherical or porous morphology by adjusting the concentration of the nanoparticle dispersion. As a demonstrative application, the resulting composite micro-particles have been used as photocatalysts for the removal of methylene blue under UV irradiation. In the case of silica microparticles containing AZO nanoparticles, the adsorption of organic pollutants combined with photocatalytic decomposition was found to be effective, and trace amounts of the pollutant remained after the removal process.