Stable dispersion of antimony-doped tin oxide nano-powder was prepared by wet attrition process by comminuting aggregated ATO nano-powder using the titanate coupling agent as a dispersant to form the chemisorbed layer on the particle surface. The feed solution of the ATO dispersion and PVP was prepared for electro-spun fibers on the glass substrate. The surface resistance of the fibrous ATO film after electrospinning for 30 minutes was in the order of 105 Ω/□, which is sufficient for anti-static coating. The optical transmittance of ATO fibers was confirmed by measuring the visible light transmittance.

Iron oxide nanoparticles were incorporated to form composite microspheres of SiO2 and Fe2O3 for magnetic separation of the particles after adsorption or photochemical decomposition. Economic material, sodium silicate, was purified by ion exchange to prepare aqueous silicic acid solution, followed by mixing with iron oxide nanoparticles. Resulting aqueous dispersion was emulsified, and composite microspheres of SiO2 and Fe2O3 was formed from the emulsion droplets as micro-reactors during heating. Removal of methylene blue using the composite microspheres was performed by batch adsorption process. Synthesis of composite microspheres of silica containing Fe2O3 and TiO2 nanoparticles was also possible, the particles could be separated using magnets efficiently after removal of organic dye.

Fixed beds were adopted for removal of organic dye from water by photocatalytic decomposition or adsorption. To this end, macroporous titania or silica micro-particles were synthesized from emulsions as micro-reactors and packed in the bed. During feeding aqueous methylene blue solution, UV light was irradiated for generation of active radicals for removal of dye by photocatalytic decomposition. Porous silica particles were also used as adsorbents in the bed for continuous adsorption of organic dye. For regeneration of the porous titania or silica particles, rinsing with fresh water was carried out before repeated cycles.

In this study, Taylor-vortex reactor was adopted to synthesize silica nanoparticles from sodium silicate solution and carbon dioxide. The outstanding advantages of the reactor have been demonstrated by comparing the synthesis results of silica nanoparticles by Erlenmeyer reactor. The results showed that silica particles synthesized from Taylor-vortex reactor are smaller in size than silica particles synthesized from the Erlenmeyer reactor. SEM images and histogram of particle size distribution obtained from experiments clearly exhibited that the concentration of SiO₂ in the solution, reaction temperature, and rotation speed of the cylinder significantly affected morphology as well as size of the silica particles.