Kinetic models for redox chemistry of disinfectant decay and toxic disinfection byproduct formation are essential to ensure water quality and protect public health; however, analytical limits have hindered model development. Considerable work has been done to develop kinetic models for chloramine chemistry, the second most common disinfectant in the US, but the impact of bromide has remained elusive. When bromide is present in source water, brominated haloamines form, decay more rapidly, and generate greater concentrations of DBPs than chloramines. At drinking water disinfection conditions, five haloamines can form and decay and the inability to monitor these species simultaneously has prevented the effective development of a robust kinetic model. Proton transfer time of flight mass spectrometry (PTR-ToF-MS) was used to monitor aqueous concentrations of the five haloamines relevant to chloramine disinfection. The technique, designed for measuring gas phase compounds, was shown to be capable of real-time measurement of aqueous haloamine concentrations with a sensitivity 1 to 3 orders of magnitude greater than other methods. The application of PTR-ToF-MS to monitor disinfection kinetics has significantly aided the development of comprehensive kinetic models for disinfection and opens a new range of applications for PTR-ToF-MS for measuring aqueous concentrations of volatile compounds.

Simultaneous time-resolved aqueous haloamine measurement empowers robust kinetic model analysis

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