PHOTODEGRADATION OF SURFACTANTS .14. FORMATION OF NH4- IONS FOR THE PHOTOCATALYZED MINERALIZATION OF NITROGEN-CONTAINING CATIONIC, NONIONICAND AMPHOTERIC SURFACTANTS( AND NO3)

The photo-oxidation of cationic, non-ionic and amphoteric nitrogen-con taining surfactants (N-dodecylpyridinium chloride (DPC) and benzyl-tet radecyldimethyl-ammonium chloride (BTDAC); dodecanoyl-N-(2-hydroxyethy l) amide (N-DHA) and dodecanoyl-N,N-bis(2-hydroxyethyl) amide (N,N-DHA ); dodecyl-beta-alanine (C-12-beta-Ala) and N-(2-hydroxydodecyl)-N-(2- hydroxyethyl)- beta-alanine (C-12-beta-HAA)) was examined in UV-illumi nated, air-equilibrated aqueous titania suspensions. Variations in the surface tension of the photooxidized surfactant solutions were monito red as a function of the irradiation time. The formation of ammonium a nd nitrate ions, together with the evolution of carbon dioxide, was in vestigated for the various surfactant chemical structures to obtain me chanistic information on the mineralization pathways. The yield of NH4 + ions was 4-13 times greater than the yield of NO3- ions. The amount of NH4+ ions formed depends on the structures of the surfactants. Mech anistic details of the photocleavage of the alkyl chains were inferred by probing the oxidation of sodium dodecanoate. The intermediates for med during the temporal photomineralization of the surfactant species were identified by high-frequency Fourier transform (FT) proton nuclea r magnetic resonance (NMR) spectroscopy.