PHOTODEGRADATION OF SURFACTANTS .6. COMPLETE PHOTOCATALYTIC DEGRADATION OF ANIONIC, CATIONIC AND NONIONIC SURFACTANTS IN AQUEOUS SEMICONDUCTOR DISPERSIONS

Various kinds of anionic (e.g., C12-DBS, C12-DS, C12-LES-3, C14-AOS, and C12-DG), cationic (e.g., C16-HTAB and C12-BDDAC) and nonionic (e.g., NPEn (n = 7, 9, 17, 50), C18-PEA-15, C12-14-BHA, C12-14-PAE-10, C12-14-NOE and C14-16-NOE) surfactants have been photodegraded in a heterogeneous dispersion of TiO2 semiconductor particles under UV illumination. These surfactants are ultimately converted to CO2. A relationship between the structure of surfactants and the photodegradation rate is indicated in a comparison of the results with literature studies of biodegradation. CO2 evolution from the photooxidation of anionic surfactants is faster than that observed from cationic surfactants in the initial stages of irradiation (2̃h). The nonionic surfactants photodegrade more slowly, evolving CO2 at about 20% mineralization yield. UV-illuminated titanium dioxide affords strongly oxidizing catalytic sites, irrespective of the structure of surfactant. © 1990.