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Nano Ti02 photocatalytic degradation the air VOCs technologies by the widespread concern at home and abroad . The perspective of this paper to light in the catalytic reaction of toxic and hazardous intermediates and health risks , select TiO2 ( Degussa P25 ) , N- TiO2 , C- TiO2 and Cu-TiO2 catalyst , based on PTR-MS measurements intermediates information Gas toluene and benzene, formaldehyde photocatalytic degradation mechanism , the study evaluated the intrinsic characteristics of the photocatalyst and light on the intermediates and health risks . The results show that : ( 1 ) of VOCs photocatalytic oxidation process is the combined effect of the hydroxyl radical and the valence band hole direct oxidation ; (2) toluene , benzene and formaldehyde in the photocatalytic process will produce a transition state compound , while the transition state compound in the further degradation have different path , thereby selectively produce different intermediate degradation of toluene in the present study the highest selectivity for acetaldehyde and acetone ; (3) C- TiO2 and Cu-TiO2 photocatalytic benzaldehyde intermediate The main product of formaldehyde, methanol, propylene , acetaldehyde, ethanol, 1,3 - butadiene , acrolein , acetone , acetic acid and propionic acid . Compared with the C-TiO2 , Cu - TiO2 intermediate higher toxicity of acetaldehyde , acrolein and 1,3 - butadiene concentration is higher, lower health risks . (4) with the UV light source , as compared VUV having two wavelengths of 185nm and 254nm , and the 185nm wavelength light can be generated in the air O (3P ) , the O3 · O3 - , O (1D ) , and O , and of · OH oxides such mineralization rates of toluene , there are conducive to higher toxic intermediates ( formaldehyde, acetaldehyde ) degradation into less toxic intermediate (formic acid , acetic acid) , the health risk index from 2.46 (UV light ) down to 0.96 ( VUV light source ) . Of this study is to contribute to the improvement of the practical application of photocatalytic technology photocatalyst for efficient , low health risk , the research and development of components are theoretically significant guidance .
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