| 초록 |
High temperature ( gt;300 o C) post-treatment of two-dimensional graphene oxide-coupled titania (GO-TiO 2 ) hybrids may enhance their photocatalytic performances. This concept has not yet been fully assessed. In the present study, we explored the applicability of GO-TiO 2 hybrids synthesized using a chemical mixing method, followed by post-treatment under various thermal conditions (200-500 o C), for the degradation of low-concentration gas-phase 2-ethyl-1-hexanol (2E1H) in continuous-flow mode under visible-light illumination. The morphological and optical characteristics of the synthesized photocatalysts were investigated by field-emission transmission electron microscopy, thermal gravimetric analysis, X-ray diffraction technique, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, and N 2 adsorption-desorption analysis. The GO-TiO 2 hybrid post-treated at 400 o C exhibited longer breakthrough and saturation times and a higher capacity for 2E1H adsorption than did GO-TiO 2 post-treated at 200 o C. The photocatalytic 2E1H degradation efficiencies of the post-treated GO-TiO 2 hybrids were superior to those of the untreated GO-TiO 2 hybrid and neat TiO 2 samples. Moreover, the photocatalytic activities of the GOkTiO 2 hybrids increased as the post-treatment temperature increased from 200 to 400 o C, and decreased as the temperature was further increased to 500 o C, indicating that the treatment temperature can be increased up to at least 400 o C without significant reduction of the photocatalytic performance. The photocatalytic activity of the GO-TiO 2 hybrid post-treated at 400 o C depended strongly on three process parameters: relative humidity, initial contaminant concentration, and catalyst mass. There was no appreciable loss of photocatalytic efficiency for the GO-TiO 2 hybrid post-treated at 400 o C after five cycles. The average 2E1H mineralization efficiency was 55.1%, while the average photocatalytic efficiency was 99.3%. Two gaseous organic compounds, i.e., 3-heptanone and 2-ethyl hexanal, and carbon monoxide were identified as the primary partially oxidized intermediates. The average carbon monoxide concentration (0.49ppm) was well below the permissible 8-h exposure level (25ppm). |
