Cyclodextrin-enhanced 1,4-dioxane treatment kinetics with TCE and 1,1,1-TCA using aqueous ozone

Abstract Enhanced reactivity of aqueous ozone (O 3 ) with hydroxypropyl-β-cyclodextrin (HPβCD) and its impact on relative reactivity of O 3 with contaminants were evaluated herein. Oxidation kinetics of 1,4-dioxane, trichloroethylene (TCE), and 1,1,1-trichloroethane (TCA) using O 3 in single and multiple contaminant systems, with and without HPβCD, were quantified. 1,4-Dioxane decay rate constants for O 3 in the presence of HPβCD increased compared to those without HPβCD. Density functional theory molecular modeling confirmed that formation of ternary complexes with HPβCD, O 3 , and contaminant increased reactivity by increasing reactant proximity and through additional reactivity within the HPβCD cavity. In the presence of chlorinated co-contaminants, the oxidation rate constant of 1,4-dioxane was enhanced. Use of HPβCD enabled O 3 reactivity within the HPβCD cavity and enhanced 1,4-dioxane treatment rates without inhibition in the presence of TCE, TCA, and radical scavengers including NaCl and bicarbonate. Micro-environmental chemistry within HPβCD inclusion cavities mediated contaminant oxidation reactions with increased reaction specificity.