Kinetics and Transformations of Diverse Dissolved Organic Matter Fractions with Sulfate Radicals

Dissolved organic matter (DOM) scavenges sulfate radicals (SO4 center dot-), and SO4 center dot--induced DOM transformations influence disinfection byproduct (DBP) formation when chlorination follows advanced oxidation processes (AOPs) used for pollutant destruction during water and wastewater treatment. Competition kinetics experi-ments and transient kinetics experiments were conducted in the presence of 19 DOM fractions. Second-order reaction rate constants for DOM reactions with SO4 center dot- (kDOM,SO4 center dot-) ranged from (6.38 +/- 0.53) x 106 M-1 s(-1) to (3.68 +/- 0.34) x 10(7 )MC(-1 )s(-1). kDOM,SO4 center dot- correlated with specific absorbance at 254 nm (SUVA254) (R-2 = 0.78) or total antioxidant capacity (R-2 = 0.78), suggesting that DOM with more aromatics and antioxidative moieties reacted faster with SO4 center dot-. SO4 center dot- exposure activated DBP precursors and increased carbonaceous DBP (C-DBP) yields (e.g., trichloromethane, chloral hydrate, and 1,1,1-trichloropropanone) in humic acid and fulvic acid DOM fractions despite the great reduction in their organic carbon, chromophores, and fluorophores. Conversely, SO4 center dot--induced reactions reduced nitrogenous DBP yields (e.g., dichloroacetonitrile and trichloronitromethane) in wastewater efuent organic matter and algal organic matter without forming more C-DBP precursors. DBP formation as a function of SO4 & BULL;- exposure (concentration x time) provides guidance on optimization strategies for SO4 & BULL;--based AOPs in realistic water matrices.