Abstract: The adsorption and photocatalytic degradation of heptene on TiO₂/SiO₂ photocatalyst under the irradiation of UV light were investigated carefully in the presence of NO₂. By means of GC-MS and FT-IR， we respectively determined the intermediate products of the three different reaction systems, and accordingly deduced the possible reaction mechanisms. The experiment data indicate that M_max (the maximum adsorption amount of TiO₂/SiO₂ for heptene) is 3.10 mg, and is increased to 3.80 mg in the presence of NO₂（44.64 μmol/L）. In the photocatalytic degradation of heptene, addition of a large amount of NO₂ (NO₂≥89.28 μmol/L) can accelerate the photodegradation reaction rate of heptene, but its mineralization degree with the addition of NO₂ is lower than that without the addition of NO₂.

Key words: photocatalysis, NO₂, heptene, adsorption, degradation