Probing the reaction kinetics of chlorine radicals (Cl•/Cl2•−) with N-nitrosamines

Abstract

N-nitrosamines are great concern in potable water reuse. This study investigated the reaction kinetics of chlorine radicals (Cl• and Cl2•−) with N-nitrosamines. The second-order reaction rate constants of Cl• (kCl•) and Cl2•− (kCl2•−) with eight N-nitrosamines at pH 7.0 varied in the range of (5.02 ± 0.41)–(57.1 ± 4.25) × 108 M−1 s−1 and (0.46 ± 0.04)–(10.6 ± 0.73) × 108 M−1 s−1, respectively. The numbers of methylene groups (#−CH2−) showed a good positive correlation with kCl• (R2 = 0.71), but not with kCl2•−. The degradation of eight N-nitrosamines under UV/chlorine advanced oxidation process (AOP) slightly increased by 1–18% in contrast to UV irradiation alone, and Cl− in the AOPs cannot inhibit their removal. The results improved the understanding of the fate of N-nitrosamines in chlorine radical-involved AOPs.