Photocatalytic degradation of Michler's Ethyl Ketone in titanium dioxide dispersions under UV irradiation

Michler's Ethyl Ketone (MEK) can be degraded photocatalytically under UV irradiation in aqueous dispersions. In the presence of both UV light illumination and TiO₂ catalyst, MEK was more effectively degraded than with either UV or TiO₂ alone. Results obtained show rapid and complete oxidation of MEK after 20-h, and more than 94% of the MEK was mineralized after a 48-h exposure to UV-365 nm irradiation. To obtain a better understanding on the mechanistic details of this TiO₂-assisted photodegradation of the MEK with UV irradiation, 19 intermediates of the process were separated, identified, and characterized by HPLC-ESI-MS and GC-MS techniques in this study. The analytical results indicated that the photocatalytic degradation of MEK yielded intermediates such as N-hydroxyethylated species, N-de-ethylated compounds, aminobenzoic acid derivatives, aminobenzene derivatives, and aliphatic products. The possible degradation pathways were proposed and discussed on the basis of the evidence of oxidative intermediate formation. The reaction mechanisms of TiO₂/UV proposed in this research should prove useful in future efforts to breakdown the organic compounds in wastewater.