Photodegradation of Surfactants. 8. Comparison of Photocatalytic Processes between Anionic Sodium Dodecylbenzenesulfonate and Cationic Benzyldodecyldimethylammonium Chloride on the TiO2 Surface

Article abstract of DOI:10.1021/j100184a037

Anionic DBS and cationic BDDAC surfactants were decomposed photocatalytically in air-equilibrated aqueous TiO2 dispersions under Hg-lamp irradiation.The cleavage of the aromatic moiety, the intermediacy of peroxides and aldehydes, and the ultimate mineralization to CO2 were examined for DBS and compared to those of BDDAC.The anionic DBS photodegrades faster than the cationic BDDAC.The aromatic moiety in the surfactant structure is decomposed more rapidly than the alkyl chain.Evidence for the formation of reactive OH radicals was obtained using spin-trapping (DMPO) ESR spectroscopy.The photodegradation kinetics are discussed in terms of Langmuir-Hinshelwood model.A photodegradation mechanism is proposed on the basis of the experimental results.