Utilization of Fin-Installed Annular Reactors Coated with Visible Light- or Ultraviolet-Driven Photocatalysts for Removal of Gas-Phase Monocyclic Aromatic Compounds

To date, studies on the degradation of gas-phase pollutants by fin-installed photocatalytic reactors are limited. The present study investigated continuous-flow annular photocatalytic reactors installed with fins for efficient removal of four gaseous monocyclic aromatic compounds using two different photocatalysts (unmodified titanium dioxide [TiO(2)] and S-doped TiO(2)). The average degradation efficiencies, which were calculated by comparing benzene, toluene, ethyl benzene, and o,m,p-xylene concentrations measured at the photocatalytic reactor inlet and outlet, obtained from the 6-h photocatalytic process of a nine-fin-installed unmodified TiO(2)/ ultraviolet (UV) system were 63%, 76%, 81%, and 90% for benzene, toluene, ethyl benzene, and o,w,p-xylene, respectively; for the unmodified Ti02/UV system without fins, the degradation efficiencies were 31%, 45%, 53%, and 56%, respectively. For the nine-fin-installed S-doped TiO(2)/visible-light system, the efficiencies were 30%, 43%, 55%, and 73%, respectively; for the no-fin S-doped TiO(2)/visible-light system, the efficiencies were 13%, 24%, 34%, and 46%, respectively. These results demonstrated that fin-installed photocatalytic reactors enhanced the degradation efficiencies for all target compounds and that the degradation efficiencies increased gradually with an increasing number of fins. In addition, under the present experimental conditions, both input concentrations of target compounds and flow rates were found to be important parameters for the photocatalytic mechanism of these fin-installed photocatalytic units. Average degradation efficiencies obtained from the six-fin unmodified TiO(2)/UV system decreased as the input concentrations increased. Similarly, degradation efficiency decreased as the flow rate increased.