Reaction Kinetics and Efficiencies for the Hydroxyl and Sulfate Radical Based Oxidation of Artificial Sweeteners in Water

Over the past several decades, the increased use of artificial sweeteners as dietary supplements has resulted in rising concentrations of these contaminants being detected in influent waters entering treatment facilities. As conventional treatments may not quantitatively remove these sweeteners, radical-based advanced oxidation and reduction (AO/RP) treatments could be a viable alternative. In this study, we have established the reaction kinetics for both hydroxyl ((OH)-O-center dot) and sulfate (SO4 center dot-) radical reaction with five common artificial sweeteners, as well as their associated reaction efficiencies. Rate constants for acesulfame K, aspartame, rebaudioside A, saccharin, and sucralose were <2 x 10(7), (2.28 +/- 0.02) x 10(9), (2.1 +/- 0.1) x 10(8), <2 x 10(7), and (1.7 +/- 0.1) x 10(8) M-1 s(-1) for the sulfate radical, and (3.80 +/- 0.27) x 10(9), (6.06 +/- 0.05) x 10(9), (9.97 +/- 0.12) x 10(9), (1.85 +/- 0.01) x 10(9), and (1.50 +/- 0.01) x 10(9) M-1 s(-1) for the hydroxyl radical, respectively. These latter values have to be combined with their corresponding reaction efficiencies of 67.9 +/- 0.9, 52.2 +/- 0.7, 43.0 +/- 2.5, 52.7 +/- 2.9, and 98.3 +/- 3.5% to give effective rate constants for the hydroxyl radical reaction that can be used in the modeling of the AOP based removal of these contaminants.