Enhanced photocatalytic decomposition of nonylphenol polyethoxylate by alkyl-grafted TiO2-MCM-41 organic-inorganic nanostructure

n-Octyl groups were grafted onto the pore walls of TiO2-MCM-41 in which TiO2 was highly dispersed in the nanopores (8.7 wt% as TiO2). and the photocatalytic properties for decomposition of dilute 4-nonylphenol polyethoxylate (NPEO) in water were investigated. The activities were evaluated on the basis of the benzene ring decomposition rates. n-Octyl-grafted TiO2-MCM-41 (C8-TiO2-MCM-41) efficiently decomposed dilute NPEO. The activity of C8-TiO2-MCM-41 per TiO2 weight was higher than that of P-25 TiO2 catalyst under the same conditions. In contrast, the activity of TiO2-MCM-41 without alkyl grafting was low. NPEO at low concentrations in solution (less than 5 ppm) was preferentially adsorbed onto C8-TiO2-MCM-41, while the adsorption onto TiO2-MCM-41 under the same conditions was small. The higher activity of C8-TiO2-MCM-41 was ascribed to the highly concentrated NPEO in the hydrophobic nanospaces. Photoirradiation of C8-TiO2-MCM-41 in water for 3 h decreased its carbon content by approximate to17%. but further irradiation for 7h brought about only a further 8% decrease, demonstrating a relatively long lifetime for the alkyl groups grafted onto the C8-TiO2-MCM-41. (C) 2004 Elsevier Inc. All rights reserved.