Unveiling O3 and HO· role on NDMA degradation mechanism in the atmosphere: A combined theoretical and experimental study

N-nitrosodimethylamine (NDMA), a highly potent carcinogen, poses significant pollution concerns in the atmosphere. The experimental methods and density functional theory (DFT) methods are employed herein to unveil the role of O3 and HO·role on the NDMA degradation mechanism in the atmosphere. The HO· plays a key role in NDMA degradation with the low Gibbs energy barrier 35.9 kJ/mol, while ozone could enhance the intermediate (CH2·)CH3NO2 degradation through O-addition without energy barriers. The main NDMA degradation pathway is through H-abstraction by HO· and O-addition by ozone molecule to form an intermediate (CH2O·)CH3NO2, finally leading to CH3NHCHO,(CH3)2NHCHO, and CH3NO2 formation. These products are not the NDMA precursors during ozonation. The Acid gas can promote the NDMA degradation. The results indicate that the method producing HO and ozone can remove NDMA in the atmosphere effectively.