Processes of formation of NH4+ and NO3- ions during the photocatalyzed oxidation of N-containing compounds at the titania/water interface

Nitrogen-containing substrates such as amino acids, amides, succinimide, imidazole, hydroxylamine and urea were photodegraded in illuminated TiO2 suspensions, and the temporal course of formation of NH4+ and NO3- ions was monitored. The hydroxylated nitrogen moiety in a molecule was predominantly converted to NO3- ions, whereas a primary amine and/or an amide were exclusively transformed to NH4+ ions under the prevailing conditions, Heterocyclic nitrogen groups in imidazole were converted to both NH4+ and NO3- ions via the intermediates whose structures were the primary amine and hydroxylamine, respectively, The influence of chemical structure on formation of NH4+ and NO3- ions is discussed from the view point of adsorption behaviours of substrates onto the TiO2 surface.