Natural organic matter (NOM) can simultaneously react as the initiator, promoter and inhibitor in �OH chain reactions in water ozonation. The rate constants of NOM in these reactions, however, have never been explicitly quantified due to their complexity, resulting in difficulties to quantitatively describe the influences of NOM on the degradation of emerging contaminants by ozonation. In this study, a new experimental approach combining the transient steady-state �OH model, the Rct concept and the pseudo first-order ozone decomposition model was developed to determine these rate constants. With the addition of an external inhibitor (tert-butanol), the rate constants of NOM as the initiator and inhibitor can be determined from the slope and intercept of the plot of 1/Rct vs. the external inhibition capacity, respectively. The rate constant of NOM as the promoter and that in the direct reaction with ozone can be determined from the slope and intercept of the plot of pseudo-first-order ozone decomposition rate constant vs. Rct, respectively. The theoretical background of this method was provided and validated with model compounds. The rate constants of Suwannee River fulvic acid and a natural water NOM were determined using the developed method. The effects of pH and temperature on these rate constants were also evaluated.  With these rate constants, the influences of NOM on the degradation of ibuprofen, an �OH-reactive pharmaceutical compound, can be successfully modelled.

Decoding the role of natural organic matter on OH radical formation in water ozonation and removal of emerging contaminants

248th National Meeting (2014)

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