Catalytic activation of peracetic acid with tungsten-modified iron oxides for decomposing pharmaceuticals in water

초록

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants in aquatic environments due to their persistence and ecological risks. Acetaminophen (APAP), one of the most frequently detected PPCPs, is poorly removed in conventional wastewater treatment plants. This study developed a reliable advanced oxidation process (AOPs) by activating peracetic acid (PAA) with tungsten-modified iron oxide (WF) catalysts without UV irradiation. PAA was successfully synthesized on-site under an optimal condition of acetic acid:hydrogen peroxide = 2:1 with 0.6 M sulfuric acid. WF catalysts were prepared via a combustion route and characterized as tungsten-substituted gamma-Fe2O3 with favorable magnetic properties for facile recovery. Under optimal conditions, complete APAP degradation was achieved within 30 min (2 g L-1 of WF 2, 1 mM of PAA, 5 mg L-1 of APAP, and a solution pH of 4.0) due to effective PAA activation by WF catalysts. Scavenger experiments identified singlet oxygen as the dominant reactive oxygen species, followed by superoxide radicals, whereas hydroxyl and carbon-centered radicals contributed marginally, confirmed with EPR analysis. The process remained robust in the presence of natural organic matter and alkalinity, and WF catalysts retained high activity for three reuse cycles before gradual attenuation. Nine transformation products were detected by LC-MS/MS, and two major degradation pathways were proposed. Ecotoxicities of the resulting products and the parent compound were estimated using the ECOSAR program, showing the formation of non-toxic, smaller intermediate products. These findings suggest that the WF/PAA system is an energy-efficient and environmentally benign alternative to conventional sulfate and halogen-based oxidation processes, highlighting its promise for practical water treatment applications.

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