Photodegradation of benzene, toluene and xylenes under visible light applying N-doped mixed TiO2 and ZnO catalysts

• Nitrogen doped TiO2/ZnO photocatalysts were synthesised and characterised.
• Nitrogen doping reduced the band gap energy by 0.48 eV.
• Benzene, toluene and xylene solutions were 99% degraded in 240 min.

N-doped TiO2/ZnO catalysts were prepared by sol–gel technique and calcined at 380 and 500 °C. Its photocatalytic activity was evaluated in the photodegradation of benzene, toluene and xylenes (BTX) under visible-LED light and compared with the undoped TiO2/ZnO activity. The amount of doped nitrogen was found to be 0.64 at%. Concentrations of BTX were analysed by gas chromatography applying the headspace technique. The NTiO2/ZnO catalyst calcined at 500 °C led to reductions of benzene, toluene and xylenes concentrations greater than 80 wt% after 120 min of irradiation. The photocatalytic reactions followed the first order kinetics.

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