HETEROGENEOUS PHOTOCATALYTIC TRANSFORMATIONS OF S-TRIAZINE DERIVATIVES

Photocatalytic processes arising from irradiated semiconductor oxide s uspensions containing 1,3,5-triazine (s-triazine) derivatives are desc ribed. Whereas unsubstituted 1,3,5-triazine undergoes hydrolysis, irre spective of the presence of the photocatalyst, other chloro-, amino-, mercapto-, allyloxo-, carboxy- derivatives give rise, in the presence of band-gap excited semiconductor oxide, to nearly stoichiometric form ation of 2,4,6-trihydroxy-1,3,5-triazine (cyanuric acid). This last co mpound is stable toward photocatalytic conditions as well as to (OH)-O -. chemically generated in homogeneous solution (H2O2/UV or Fenton's r eagent). Only partial conversion in cyanuric acid is observed for 2,4, 6-tris(2-pyridyl)-1,3,5-triazine and possible explanation is given. Th e formation of inorganic species (nitrate, chloride, sulfate and ammon ium ions) is reported and the mechanism of their evolution presented.