REACTIONS AND PRODUCTS OF CHLORAMINATION

The stoichiometry of the reaction of chlorine with excess ammonia in dilute aqueous solution was investigated at near-neutral pH as well as at an elevated pH (range of 9.3-9.6). A significant portion of chlorine was incorporated into unrecognized reaction products at near-neutral pH, and essentially none at the elevated pH. The absence of detectable nitrite did not prohibit the production of significant amounts of nitrate at the pH levels investigated. The relative significance of the nitrate production increased upon dilution of the reactants at near-neutral pH, with nitrate becoming the primary end product of nitrogen oxidation under conditions approaching those encountered in the disinfection of drinking water. The decomposition of hydrazine appeared to be responsible for the formation of nitrogen gas at the elevated pH. No explanation can be offered for the significant quantities of nitrate produced at that pH.