Design of H3PW_(12)O_(40)/TiO2 and Ag/H3PW_(12)O_(40)/TiO2 film-coated optical fiber photoreactor for the degradation of aqueous rhodamine B and 4-nitrophenol under simulated sunlight irradiation

摘要

In order to improve sunlight-energy utilization efficiency of the photocatalyst for the degradation of organic pollutants in wastewater, a novel photoreactor that comprised H3PW_(12)O_(40)/TiO2 or metallic Ag deposited H3PW_(12)O_(40)/TiO2 film-coated optical fiber bundles was designed by the steps of sol-gel, hydro-thermal treatment, photoreduction, and dip coating. The H3PW_(12)O_(40)/TiO2 or Ag/H3PW_(12)O_(40)/TiO2 film exhibited anatase phase, mesoporosity, and charge transfer band in the range of 200-400 nm or 200-800 nm. The photocatalytic activity of the H3PW_(12)O_(40)/TiO2 and Ag/H3PW_(12)O_(40)/TiO2 film-coated optical fibers was evaluated by the degradation of rhodamine B and 4-nitrophenol in aqueous solutions under the irradiation of commercial Xe lamp and self-made solar simulator (320 nm <λ < 680 nm). The enhanced photocatalytic activity of the H3PW_(12)O_(40)/TiO2 or Ag/H3PW_(12)O_(40)/TiO2 film in comparison of TiO2 film was obtained and explained in terms of the synergistic photocatalytic effect between Keggin unit and TiO2 as well as surface plasmon resonance effect of metallic Ag; and considerably high photocatalytic activity of the H3PW_(12)O_(40)/TiO2 and Ag/H3PW_(12)O_(40)/TiO2 film in the optical fiber photoreactor is explained by the superior light-energy utilization of the catalyst in the optical-fiber reactor. Finally, the reusability of the catalyst film was evaluated through six consecutive catalytic runs.