Synthesis of superparamagnetic MnFe2O4/mSiO2 nanomaterial for degradation of perfluorooctanoic acid by activated persulfate

Pengfei Ji; Feng Zhu; Jiamin Zhou; Jintao Ma; Hongyong Wang; Gang Xu

doi:10.1007/s11356-021-17782-y

Synthesis of superparamagnetic MnFe₂O₄/mSiO₂ nanomaterial for degradation of perfluorooctanoic acid by activated persulfate

Environ Sci Pollut Res Int. 2022 May;29(24):37071-37083. doi: 10.1007/s11356-021-17782-y. Epub 2022 Jan 15.

Authors

Pengfei Ji^{1

2}, Feng Zhu¹, Jiamin Zhou¹, Jintao Ma¹, Hongyong Wang³, Gang Xu⁴

Affiliations

¹ School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, People's Republic of China.
² Key Laboratory of Organic Compound Pollution Control Engineering, Ministry of Education, Shanghai, 200444, People's Republic of China.
³ Institute of Applied Radiation of Shanghai, Shanghai University, Shanghai, 200444, People's Republic of China. hongyong@pku.edu.cn.
⁴ School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, People's Republic of China. hongyong@pku.edu.cn.

PMID: 35031993
DOI: 10.1007/s11356-021-17782-y

Abstract

In this paper, magnetic MnFe₂O₄/mSiO₂ nanocomposites were successfully synthesized, and the activation performance of the materials for persulfate was evaluated by the degradation efficiency of perfluorooctanoic acid. The structure of the catalyst was proved to be a core-shell structure by several characterization methods. The mesoporous silicon coating can effectively avoid the agglomeration of MnFe₂O₄ and at the same time increase the contact area with the reactants. A comparison of different catalyst addition conditions demonstrates that MnFe₂O₄/mSiO₂ can effectively activate the persulfate. The optimal reaction conditions were investigated by several key influencing factors. It was experimentally demonstrated that about 90% of PFOA (10 mg·L^-1) could be decomposed under the conditions of 0.4 g·L^-1 MnFe₂O₄/mSiO₂ and PS, pH 5.68, and 25 °C within 4 h; the defluorination rate reached 58.33%. In addition, the cyclability and stability tests demonstrated that MnFe₂O₄/mSiO₂ is a stable material that can be recycled. Furthermore, XPS characterization and radical scavenging experiments demonstrated that sulfate radicals (SO₄·^-) and hydroxyl radicals (OH) play a major role in the reaction of MnFe₂O₄/mSiO₂ activated PS. Subsequently, the degradation products were detected by high-performance liquid chromatography tandem triple quadrupole mass spectrometry, indicating that the degradation of PFOA is a gradual process of defluorination and decarbonization in the presence of free radicals. Finally, the metal leaching rate is tested to prove that the material meets environmental requirements while reacting efficiently. In conclusion, this study shows that MnFe₂O₄/mSiO₂ is an easily recoverable and highly efficient and stable material that has great potential for PS activation to treat organic pollutants in water.

Keywords: Degradation pathway; Magnetic; MnFe2O4/mSiO2 nanocomposite; Perfluorooctanoic acid; Reaction mechanism; Recoverable.

MeSH terms

Caprylates / chemistry
Fluorocarbons
Magnetic Iron Oxide Nanoparticles
Nanocomposites* / chemistry
Water Pollutants, Chemical* / analysis

Substances

Caprylates
Fluorocarbons
Water Pollutants, Chemical
perfluorooctanoic acid