Intramolecularly selective decomposition of surfactant molecules on photocatalytic oxidative degradation over TiO2 photocatalyst

Investigation on oxidative mineralization of various surfactants over TiO2 photocatalyst reveals an anomalously retarded degradation of the trimethyla mmonium moiety in cationic surfactants. Model reactions using tetraalkylamm onium chlorides as substrates confirm that the stepwise behavior of the min eralization time courses is ascribed to intramolecularly selective decompos ition caused by a considerably slow degradation rate of the methyl groups d irectly bound to the quaternary nitrogen. A strong inhibition effect of bro mide or iodide anions preventing the complete mineralization is also reveal ed. (C) 2009 Elsevier Science B.V. All rights reserved.