Preparation of TiO₂/SiO_x double-layer films on glass beads and its application to NO and SO₂ removal

Glass beads were coated with SiO_x thin film as the first layer and with TiO₂ thin film as the second layer by a rotating cylindrical PCVD reactor. The thicknesses of TiO₂/SiO_x double-layer films were measured by scanning electron microscopy. Glass beads coated with TiO₂/SiO_x double-layer films were packed inside the cylindrical reactor. NO and SO₂ removal by dielectric barrier dischargephotocatalyst (DBD-P) hybrid process was tested for various conditions of process variables. The NO and SO₂ removal efficiencies were improved by using a combination of dielectric barrier discharge and photodegradation by TiO₂/SiO_x double-layer films. The stronger the applied voltage is, the higher the pulse frequency is, or the longer the gas residence time is, the higher the NO and SO₂ removal efficiencies become. In this study, we found that the glass beads coated with TiO₂/SiO_x double-layer films by a rotating cylindrical PCVD reactor could be used effectively to remove NO and SO₂ by DBD-P hybrid process.