The reaction of hypochlorous acid (HOCl) with superoxide radical (O2●–) has been investigated here as the basis for a novel advanced oxidation process (AOP). Hydroxyl radical (HO●) can be generated directly by dosing alkaline aqueous stocks of O2●– to circumneutral pH solutions of free available chlorine (FAC – including HOCl and OCl–), and can in turn serve as the precursor of various reactive chlorine species (RCS), including chlorine radical, chlorine monoxide radical and dichloride radical. Radical production was optimal at a molar ratio of [O2●–]0/[FAC]0 ~ 2, with ~0.8 mol HO● formed/mol FAC consumed, leading to maximal cumulative HO● and RCS radical exposures comparable to or higher than many AOPs currently in use in (waste)water treatment. Direct formation of disinfection byproducts, including oxyhalides, trihalomethanes, and haloacetic acids, was minimal. This presentation will highlight key aspects of process chemistry, opportunities for optimization, potential applications, and future research needs.

Evaluation of hydroxyl radical and reactive chlorine species generation from the superoxide/hypochlorous acid reaction as the basis for a novel advanced oxidation process

ACS Fall 2021

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