Reactions of Monobromamine and Dibromamine with Phenolic Compounds and Organic Matter: Kinetics and Formation of Bromophenols and Bromoform.

Monobromamine (NHBr) and dibromamine (NHBr) produced from reactions of hypobromous acid (HOBr) with ammonia can react with phenolic structures of natural organic matter (NOM) to produce disinfection byproducts such as bromoform (CHBr). The reactivity of NHBr was controlled by the reaction of the bromoammonium ion (NHBr) with phenolate species, with specific rate constants ranging from 6.32 × 10 for 2,4,6-tribromophenol to 1.22 × 10 M s for phenol. Reactions of NHBr with phenol and bromophenols were negligible compared to its self-decomposition; rate constants could be determined only with resorcinol for pH > 7. At pH 8.1-8.2, no formation of CHBr was observed from the reaction of NHBr with phenol while the reaction of NHBr with resorcinol produced a significant concentration of CHBr. In contrast to NHBr, a significant amount of CHBr produced with an excess of NHBr over phenol was explained by the reactions of HOBr produced from NHBr decomposition. A comprehensive kinetic model including the formation and decomposition of bromamines and the reactivity of HOBr and NHBr with phenolic compounds was developed at pH 8.0-8.3. Furthermore, the kinetic model was used to evaluate the significance of the NHBr and NHBr reactions with the phenolic structures of two NOM isolates.