More and more attention is paid to dissolved organic nitrogen (DON) and some specific categories of amino acids are considered to be the direct precursors of nitrogenous disinfection byproducts (N-DBPs). Histidine was chosen to study the efficiency and mechanism of amino acid in UV/Cu-TiO2system. Moreover, the influences of pH, organics, and inorganic ion on the photocatalytic efficiency were also investigated. The results show that the degradation rate of DON in the UV/Cu-TiO2system was about 50% after 60 min, and it was much lower than that of histidine (72%), which indicated that a part of degraded histidine was oxidized to other N-containing organics. The optimal pH value was 7.0 for the photodegradation of histidine, and the presence of organic compound and inorganic ion would decrease the degradation performance to some extent. After 6 h irradiation, histidine was totally degraded intoNH4+, and in the following 2 h,NH4+was oxidized toNO3-firstly and thenNO3-was reduced to N2and overflowed from water, which should be attributed to the doping of Cu in the TiO2and provided a way to totally degrade the DON from the water.
Spatial variation of dissolved organic nitrogen in Wuhan surface waters: Correlation with the occurrence of disinfection byproducts during the COVID-19 pandemic
