Shang Yanan

A novel investigation into the utilization of vanadium oxide (V₂O₃) as a persulfate (PS) activator in phenanthrene degradation in an aqueous system, and its subsequent pathway, was undertaken. The V₂O₃/PS has a high thermal degradation activity for phenanthrene at either room temperature (25 °C) or higher (35 °C and 45 °C), with a better performance (up to five times reuse) and a shorter degradation time. Phenanthrene can be effectively degraded under different pH conditions (pH 3, 5, 7, and 9), with a low PS concentration (2 mmol/L), activated by a small V₂O₃ loading (0.1 g/L). The electron paramagnetic resonance (EPR) technique combined with 5,5-dimethyl-1-pyrroline N-oxide (DMPO, 0.1 mol/L), captured sulfate (SO₄⁻) and hydroxyl (OH) radical signals in the V₂O₃/PS system, generated from PS activation with V₂O₃. Free radical quenching studies revealed that both SO₄⁻ and OH contributed to phenanthrene degradation. The PS activation mechanism by V₂O₃ was elucidated. V₂O₃-activated PS produced SO₄⁻ and VO₂ via electron transfer, with VO₂ transferring a further electron to activate PS for SO₄⁻ and V₂O₅ generation, and a portion of the produced SO₄⁻ converted to OH. V₂O₃-activated PS generated four ion oxidation products (VO₂, V₂O₅, V (V) and V (IV)), whereby VO₂ and V₂O₅ actively participated in phenanthrene degradation, whereas V (V) and V (IV) provided no effective activation. A phenanthrene degradation pathway in the V₂O₃/PS system was proposed based on the identification of phenanthrene intermediates through liquid chromatography-mass spectrometry. These findings provide valuable insight into PS activation using a unique activator (V₂O₃) in the removal of environmental organic pollutants.