VUV PHOTOLYSIS OF AQUEOUS-SOLUTIONS OF NITRATE AND NITRITE

Water homolyses upon vacuum-uv excitation into HO. radicals, hydrogen atoms and with lower efficiency, hydrated electrons. These primary species induce a series of reactions partially depleting nitrate and nitrite from aqueous solutions. Depletion rates depend on the presence of dissolved oxygen and temperature. Nitrate, nitrite, peroxynitrite and N2O were identified as reaction products after irradiation of, either, nitrite and nitrate in aqueous solutions. A reaction mechanism is proposed in accord with the experimental facts and with the evidence given in the literature, where NO2. and NO. are key intermediates. NO3., NO2., NO2., NO., O2NO2., ONO2. and N2O, seem to be interrelated by many redox reactions and reaction equilibria where pH and the availability of electrons determine their occurrence. The proposed mechanism is supported by a computer program with which the observed experimental behavior could be simulated.