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| Study on the decomposition mechanism of formaldehyde and ozone byproduct in the presence of MnOx-TiO2 catalyst under UV185+254nm irradiation |
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Abstract To increase the efficiency of simultaneous removal of formaldehyde and ozone byproduct under 185nm VUV (vacuum ultraviolet) irradiation, TiO2 supported manganese oxide catalyst (MnOx-TiO2) was synthesized and used as photocatalyst. The conversion rate of HCHO and O3 byproduct significantly increased from 44.7% and 38.7% for TiO2 to 77.5% and 96.8% for MnOx-TiO2, respectively. To elucidate the decomposition mechanism of HCHO and O3 on the MnOx-TiO2 under VUV irradiation, the decomposition rates of HCHO and O3 under VUV irradiation and in dark condition (added O3) were compared, and the photocatalytic degradation of HCHO on the MnOx-TiO2 under UV254nm irradiation was also investigated. The results indicated that the HCHO was mainly oxidized via homogeneous oxidation with active oxygen species and heterogeneous catalytic oxidation with ozone on the MnOx surface. Only less than 10% HCHO could be photocatalytically degraded on the MnOx-TiO2 under UV245nm irradiation. The O3 byproduct was mainly removed via thermal catalytic decomposition on the MnOx surface. The stability of MnOx-TiO2 to catalytically decompose O3 was greatly improved when the MnOx surface was irradiated with VUV light.
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Received: 01 July 2011
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