N-Nitrosodimethylamine formation from ozonation of chlorpheniramine: Influencing factors and transformation mechanism.
As a disinfection byproduct, the detection of N-nitrosodimethylamine (NDMA) in aquatic environments across the globe has caused widespread concern due to its potential carcinogenicity. In this study, the possibility of NDMA formation from chlorpheniramine ozonation was investigated. The influencing factors including the initial chlorpheniramine concentration, ozone dose, pH, and water matrix were quantified. Furthermore, the mechanisms for chlorpheniramine transformation and NDMA formation were explored. Our results demonstrate that ozonation is effective in removing chlorpheniramine. Generation of dimethylamine (DMA) and NDMA was observed during chlorpheniramine ozonation. Higher initial chlorpheniramine concentration and ozone dose resulted in higher production of NDMA. Acidic conditions (pH≤5) did not facilitate the production of NDMA. Ozone molecules played a dominant role in chlorpheniramine degradation, and influenced DMA release and NDMA formation. DMA and NDMA generations as well as their degradations were mainly attributed to hydroxyl radicals (·OH) produced by ozone decomposition. Water matrix properties such as HCO3(-) and humic acid affected DMA and NDMA generation due to ·OH competition. The degradation intermediates of chlorpheniramine were identified, among which only the intermediates with a DMA group were attributable to NDMA formation. A possible pathway for NDMA formation from chlorpheniramine ozonation is proposed.
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, PR China.
Juan
J
Lv
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Lin
L
Wang
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
Yun
Y
Song
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China. Electronic address: liyongmei@tongji.edu.cn.
Yongmei
Y
Li
Chlorpheniramine; Influencing factor; N-nitrosodimethylamine; Ozone; Transformation mechanism