Photocatalytic Degradation of Michler's Ketone in Water by UV Light Illumination Using TiO 2 Photocatalyst: Identification of Intermediates and the Reaction Pathway

The TiO 2 /UV photocatalytic degradation of Michler's Ketone (MK) has been investigated in aqueous heterogeneous suspensions. Results obtained show rapid and complete oxidation of MK after 24‐h, and more than 97.5% of MK was mineralized after a 32‐h exposure to UV‐365 nm irradiation. Establishment of the reaction pathway was made possible by a thorough analysis of the reaction mixture identifying the main intermediate products generated. Nine intermediates have been detected by HPLC/ESI‐MS and GC/MS techniques. The photocatalytic degradation of MK proceeds through competitive reactions such as N ‐de‐methylation and destruction of the bis‐aminobenzophenone structure. The former reaction took place in a stepwise manner to yield mono‐, di‐, tri‐, tetra‐demethylated species, while the latter reaction yielded N ‐methylaminobenzene and aminobenzene. The reaction mechanisms of TiO 2 /UV proposed in this study should shed some light on future applications of the technology to the destruction of organic pollutants.