Volatile organic chloramines formation during ClO treatment.

Volatile organic chloramines are reported as the disinfection byproducts during chlorination or chloramination. However, ClO, as an important alternative disinfectant for chlorine, was not considered to produce halogenated amines. In the present work, volatile organic chloramines including (CH)NCl and CHNCl were found to be generated during the reaction of ClO and the dye pollutants. (CH)NCl was the dominant volatile DBP to result from ClO treated all four dye pollutants including Methyl Orange, Methyl Red, Methylene Blue and Malachite Green, with molar yields ranging from 2.6% to 38.5% at a ClO to precursor (ClO/P) molar ratio of 10. HOCl was identified and proved to be the reactive species for the formation of (CH)NCl, which implied (CH)NCl was transformed by a combined oxidation of ClO and hypochlorous acid. (CH)NCl concentrations in the ppb range were observed when real water samples were treated by ClO in the presence of the dye pollutants. The results suggest that these azo dyes are one of the significant precursors for the formation of HOCl during ClO treatment and that organic chloramines should be considered in ClO disinfection chemistry and water treatment.