Oxidation and reduction of nitrite ion in the TiO2 photo-induced catalytic reaction

During a photo-induced catalytic reaction under near UV irradiation to an aqueous suspension of TiO2, about 95% of NO2- was oxidized to NO3-, but NH4+ was not detected, The oxidation was inhibited by the addition of mannitol or under anaerobic conditions. The nitration of I-IPA was observed in the presence of t-buthanol, suggesting the formation of ONOO-. An ESR spectrum gave a triplet signal at g = 2.041, in the presence of NO2-, mannitol, FeSO4, and MGD, indicating the reduction of NO2- to NO.