Photodegradation of surfactants X. Comparison of the photo-oxidation of the aromatic moieties in sodium dodecylbenzene sulphonate and in sodium phenyldodecyl sulphonate at TiO2H2O interfaces

Abstract

Abstract Two isomers of sodium dodecylbenzene sulphonate (DBS) and sodium 12-phenyldodecyl sulphonate (PDS) were photodegraded in heterogeneous TiO 2 dispersions. Aromatic opening rate, CO 2 evolution, and pH variation were examined in the photodegradation process. The photo-oxidation of the aromatic moiety in DBS was faster than that in PDS. Although the photodegradation kinetics can be modelled in terms of the Langmuir—Hinshelwood equation, it was shown earlier that the kinetics data are silent as to surface vs . solution reaction. This notwithstanding, it is agreed here that pre-adsorption precedes the photo-oxidation. The participation of . OH radicals generated at the irradiated TiO 2 H 2 O interface in the photo-oxidation process was confirmed by spin-trapping electron spin resonance measurements.