Mechanisms of oxidative removal of 1,4-dioxane via free chlorine rapidly mixing into monochloramine: Implications on water treatment and reuse.

Free chlorine (HOCl) and monochloramine (NHCl) are two of the most commonly used water disinfectants in water treatment; however, the capability of rapid mixing of HOCl into NHCl to induce oxidative reactions for efficient removal of contaminants remains largely unknown. In this study, 1,4-dioxane (1,4-D) removal was quantified during the rapid mixing of HOCl into NHCl, to evaluate the effects of solution pH and HOCl-to-NHCl ratio, and to identify mechanisms by which reactive species are generated in the system. Results showed that the highest 1,4-D removal was observed at the near-neutral pH of 6 with the HOCl-to-NHCl molar ratio of 1.