Photocatalytic oxidation of 2,4,6-trinitrotoluene in the presence of ozone under irradiation with UV and visible light

The photooxidation of 2,4,6-trinitrotoluene (TNT), catalysed by nanosized photocatalysts: TiO2, WO3/TiO2, Au/TiO2 and Au/WO3/TiO2 was studied under irradiation with UV or visible light in the presence of O2 or O2–O3 mixture. The photocatalysts were characterized by the BET, XPS, TEM methods and adsorption of the model pollutant. The effectiveness of the processes of under UV-A, UV-C and visible light irradiation destruction in the presence of O3, photocatalysed by the WO3/TiO2, Au/TiO2 and Au/WO3/TiO2 samples is considerably higher than that registered in process, occurring with pure TiO2. Thus in the presence of O3 the rate constants of 2,4,6-trinitrotoluene photooxidation under UV-A, UV-C and visible light irradiation catalysed by Au/WO3/TiO2 are respectively 2.1, 1.4 and 6.2 times higher than that registered with pure TiO2. On the other side the ozone rate constants of 2,4,6-trinitrotoluene photooxidation under UV or visible light irradiation are also much higher than those, registered in the presence of O2 only. Thus under UV light irradiation the O3 rate constants of 2,4,6-trinitrotoluene photooxidation, catalysed by Au/WO3/TiO2 are 6 times higher, while under visible light they are 11 times higher than those with oxygen only. Under irradiation with UV-A, UV-C and visible light in the presence of ozone a synergistic effect has been registered, expressed most strongly in the case of TNT destruction, photocatalysed by Au/WO3/TiO2. Doping of the semiconductor materials with gold nanoparticles increases 1.4–2.2 times the rate constants of 2,4,6-trinitrotoluene mineralization, compared to the undoped samples, which is due to more efficient separation of the electron–hole charges generated upon irradiation.