Ozone-assisted photocatalytic degradation of gaseous acetaldehyde on TiO2/M-ZSM-5 (M = Zn, Cu, Mn)

M-ZSM-5 (M = Zn, Cu, Mn) catalysts were prepared by ion-exchange of M ions with H+ in H-ZSM-5. TiO2 loading on M-ZSM-5 was realized by dipping method. All the catalysts were characterized by ultraviolet and visible spectroscopy (UV–vis), X-ray diffraction (XRD) and nitrogen isothermal adsorb-desorption measurement. The catalytic activities of the samples were investigated under UV, ozone and UV–ozone for acetaldehyde degradation. The results showed that the application of photocatalytic ozonation (UV–ozone) produced the improved efficiency for acetaldehyde removal, indicating a combined effect occurred when photocatalysis and ozonation were carried out simultaneously. Transition metal ions exchanged catalyst TiO2/M-ZSM-5 increase the apparent catalysis activity by increasing acetaldehyde adsorption and ozonation at the sites of M ions. TiO2/Mn-ZSM-5 presented the highest activity with acetaldehyde conversion among the prepared samples, which was higher than that of simple additive under UV and O3. The improvement was attributed to the exchanged Mn ions and the integrated effect among adsorption, ozonation and photocatalytic reactions.