The magnetic field effect on heterogeneous photocatalytic degradation of benzene over Pt/TiO₂ has been observed by on-line GC. Time-resolved photoconductivity and in-situ FTIR were used to investigate the influence of magnetic field on the photogenerated charge carrier lifetime and the intermediate distribution, respectively. The results showed that in the presence of magnetic field the effective lifetime of the photogenerated charge carriers was prolonged with the increase of the magnetic field intensity. The results also indicated that the application of the external magnetic field not only favored the conversion of benzene, but also facilitated the transformation from phenol to quinone, resulting in improving the activities of the photocatalytic degradation.

Key words: magnetic field effect, photocatalytic degradation, time-resolved photoconductivity, in-situ FTIR, benzene