) contamination in drinking water is a growing concern. Advanced reduction processes (ARPs) are reportedly promising in relieving this concern. In this work, UV/superparamagnetic BiOCl (BiOCl loaded onto superparamagnetic hydroxyapatite) assisted with small molecule carboxylic acid (formate, citrate, and acetate), a carboxyl anion radical (
)-based ARP, was proposed to eliminate aqueous
. Formate and citrate were found to be ideal
precursor, and the latter was found to be safe for practical use.
, WHO guideline for drinking water) can be completely degraded within 3 min under oxygen-free conditions. In this process,
degradation was realized by the reduction of
(major role) and formyloxyl radical (minor role) in bulk solution. The formation mechanism of radicals and the transformation pathway of
were proposed based on data on electron paramagnetic resonance monitoring, competitive kinetics, and degradation product analysis. The process provided a sustainable decontamination performance (<5% deterioration for 10 cycles) and appeared to be more resistant to common electron acceptors (O2
, and Fe3+
) than hydrated electron based-ARPs. Phosphate based-superparamagnetic hydroxyapatite, used to support BiOCl in this work, was believed to be applicable for resolving the recycling problem of other metal-containing catalyst.
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