Sulfate radical (SO4●−)-based advanced oxidation processes (AOPs) are promising alternatives for contaminant mitigation. Dissolved organic matter (DOM) can scavenge SO4●− thus impede the SO4●−-induced reaction with micropollutants. Meanwhile, the transformation or removal of DOM can be also impacted inevitably by SO4●−-induced reaction. However, the kinetic information for reactions of SO4●− with DOM and the transformation of DBP formation during the post-chlorination have been rarely reported. We therefore systematically explored these gaps in the present work. The second-order reaction rate constants of 18 DOM isolates with SO4●− were determined using steady-state UV irradiation. The measured rate constants of the reactions between SO4●− and DOM varied 2 order of magnitudes and ranged from 6.38 × 106 M−1 s−1 to 3.60 × 107 MC−1 s−1 with an average of 1.97 × 107 MC−1 s−1. Humic acids, fulvic acids (FA), and natural organic matter (NOM) have higher reactivity toward SO4●− than effluent organic matters (EfOMs) and algal organic matter (AOM). DOM with higher aromatic carbon contents and higher total antioxidant capacity (TAC) exhibited higher reactivity toward SO4●− (Figure 1). The formation of halogenated organic byproducts and disinfection byproducts of DOM after SO4●− exposure and post-chlorination were quantified. The yield of total organic halogen (TOX) for diverse DOM was different with the increase of SO4●− exposure, which might result from the change of DOM properties. Similarly, the formation potential of DBPs was also different, but their trends were generally same as the TOX yield. This study provides the fundamental data for SO4●−-induced reaction with DOM and the guidance for regulating DBP formation in SO4●−-based AOPs.

Reactivity of sulfate radical with dissolved organic matter and formation of disinfection byproducts during post-chlorination

ACS Fall 2021

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