Enhanced abatement of pharmaceuticals by permanganate via the addition of Co3O4 nanoparticles

Abstract

Pharmaceuticals may pose serious potential risks, such as biological responses and chronic health effects, due to their ubiquitous in natural aquatic water bodies. In this study, we proposed an effective, feasible, and low-cost strategy for the abatement of pharmaceuticals (i.e., phenylbutazone (PBZ) and sulfinpyrazone (SPZ)) via Co3O4 nanoparticles (NPs) as heterogeneous catalyst in permanganate (Mn(VII)) oxidation for the first time. The performance of the Co3O4 NPs in permanganate oxidation is highly dependent on pH and its dosage. Co3O4 NPs play as electron shuttles in the catalytic permanganate oxidation process involving one-electron transfer with the oxidation of ≡CoII to ≡CoIII by permanganate and the formation of colloidal manganese dioxide (MnO2), as well as the reduction of the newly formed ≡CoIII to ≡CoII by organics and the production of oxidized organic byproducts. The degradation pathways of PBZ and SPZ in catalytic permanganate oxidation were proposed based on the liquid chromatography-tandem mass spectrometry (LC-MS/MS) results and Gaussian calculation, and the toxicity decay of pharmaceuticals during oxidation was observed. Considering the stability, reusability, and cost, Co3O4 coupled with Mn(VII) is suitable for water pretreatment and is potentially feasible for industrial application, which is not only effective for decomposing PBZ and SPZ, but also for eliminating their toxicity.