Degradation of UV-filter benzophenone-3 in aqueous solution using persulfate catalyzed by cobalt ferrite

- CoFe2O4 is an effective catalyst to activate PS for the degradation of BP-3.
- Kinetics and mechanisms of BP-3 degradation by PS/CoFe2O4 were studied.
- SO4− was the dominant radical for BP-3 decomposition.
- 15 transformation products were identified by LC-TOF-MS.
- Hydroxylation, demethylation, direct oxidation, benzene ring opening were observed.

The occurrence of benzophenone-3 (BP-3) in aquatic environments constitutes a potential risk to the environment and human health due to its phytotoxicity, carcinogenicity and endocrine disrupting effects. In this work, cobalt ferrite (CoFe2O4) prepared by chemical co-precipitation method was used as a catalyst for the degradation of BP-3. The catalyst was characterized by SEM, TEM, XRD, XPS, BET and FT-IR spectroscopy, and its catalytic activity on BP-3 removal by persulfate (PS) was then evaluated at different operating parameters (catalyst loading, reaction temperature, solution pH and PS dose). The removal of BP-3 (1.31 μM) in 6 h reached 91% under the condition of [BP-3]0: [PS]0 = 1: 1000, initial pH = 7.0, T = 25 °C and catalyst load = 500 mg L−1. In addition to the satisfactory catalytic performance, the CoFe2O4 also showed high stability and excellent recyclability. Electron paramagnetic resonance and radical quenching tests showed that sulfate radicals predominated in the decomposition of BP-3 by PS/CoFe2O4, while hydroxyl radicals also contributed to the catalytic oxidation process. Fifteen degradation products were identified by liquid chromatography-mass spectrometry (LC-MS), and two reaction pathways involving hydroxylation, demethylation, direct oxidation and benzene ring opening were proposed. This study could provide useful information for the potential application of CoFe2O4 activated PS technology to treat water and wastewaters containing BP-3.

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