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Polyacrylonitrile (PAN)-supported titania (PAN-TiO 2 ) fibers with different TiO 2 to PAN ratios were prepared, and their feasibility for indoor air cleaning applications was examined. For all target aromatic compounds, the decomposition efficiencies of PAN-TiO 2 fibers increased as the ratio of PAN:TiO 2 :N,N-dimethyl formamide increased. For the highest TiO 2 ratio (1:1:9), the decomposition efficiencies of the PAN-TiO 2 fibers were close to 100% for the target compounds over the 3-h photocatalytic process, whereas for the lowest TiO 2 ratio (1:0.05:9), they were initially less than 30% and then gradually decreased to close to zero at the end of the 3-h photocatalytic process. The decomposition efficiencies revealed a descending trend, but photocatalytic reaction rates revealed an ascending trend with increasing initial concentration and stream flow rate. Overall, these findings suggested that the PAN-TiO 2 fibers would be effectively used for indoor air aromatic compound cleaning, when operational conditions are optimized.

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In this study, one-dimensional rod-shaped titania (RST) and nitrogen-doped RST (N-RST) with different ratios of N to Ti were prepared using a hydrothermal method and their applications for purification of indoor toxic organic contaminants in a plug-flow reactor were examined under visible or ultraviolet (UV) irradiation. The surface characteristics of as-prepared photocatalysts were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-visible spectroscopy. The TEM images revealed that both pure RSTs and N-RSTs displayed uniform and nanorod-shaped structures. XRD revealed that the photocatalysts had crystalline TiO2. The UV-visible spectra demonstrated that the N-RSTs could be activated in the visible region. In most cases, N-RSTs showed higher degradation efficiencies than pure RSTs under visible-light and UV irradiation. N-RSTs with a N-to-Ti ratio of 0.5 exhibited the highest degradation efficiencies of benzene, toluene, ethyl benzene, and o-xylene (BTEX), suggesting the presence of an optimal N-to-Ti ratio for preparation of N-RSTs. In addition, the average degradation efficiencies of BTEX determined for the N-RSTs with a N-to-Ti ratio of 0.5 under visible-light irradiation for the lowest initial concentration (IC, 0.1 ppm) were 19%, 53%, 85%, and 92%, respectively, while the degradation efficiencies for the highest IC (2.0 ppm) were 2%, 8%, 17%, and 33%. These values decreased as the stream flow rate increased. Overall, the as-prepared N-RSTs could be effectively applied for degradation of toxic gas-phase organic contaminants under visible-light as well as UV irradiation.