- Title
- A Novel Enhanced Defluorination of Perfluorooctanoic Acids by Surfactant-Assisted ultrasound Coupling Persulfate
- Creator
- Lei, Yongjia; Zhao, Lirong; Zou, Jianmei; Zhang, Xiaohong; Deng, Shihuai; Shen, Fei; Fang, Cheng; Naidu, Ravi; Tian, Dong; Zhao, Li; Huang, Mei; He, Jinsong; Cheng, Zhang; Zeng, Zhenxing
- Relation
- Separation and Purification Technology Vol. 317, Issue 15 July 2023, no. 123906
- Publisher Link
- http://dx.doi.org/10.1016/j.seppur.2023.123906
- Publisher
- Elsevier
- Resource Type
- journal article
- Date
- 2023
- Description
- A novel enhanced defluorination of perfluorooctanoic acids (PFOA) by surfactant-assisted ultrasound (US) coupling persulfate (PS) was proposed in this study. Instead of adding the surfactant into the PFOA solution directly, the promoted defluorination was obtained by adding the surfactant to the US bath outside of the PFOA reactor. In this situation, the effects of the critical micelle concentration (CMC), concentration and type of the surfactant, the US frequency and the pH of the US bath liquid on the PFOA defluorination were investigated. The results demonstrated that the PFOA defluorination at low-frequency levels (25 kHz-59 kHz) was facilitated by raising US frequency. Besides, the addition of three surfactants (Triton X-100, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)) all increased the PFOA defluorination by Triton X-100 > CTAB > SDS, which is opposed to their CMC (Triton X-100: 0.28 mM＜CTAB: 1.07 mM＜SDS: 7.69 mM). Rising the surfactant concentration would not enhance the defluorination, the best one was obtained at its CMC. Moreover, changing the pH of the US bath liquid by adding acid or alkaline solution inhibited the defluorination, which might be attributed to acid or base causing damage to the chemical properties or physical structure of surfactant (certified by the SEM tests). Additionally, the mechanism of enhanced PFOA defluorination was examined by electron paramagnetic resonance analysis, which proved that adding surfactant facilitated the generation of the radicals (·OH and SO4∙-), as well as the radicals’ amount increased over time during 60 min. Finally, the inhibited defluorination of adding surfactant directly to the PFOA solution was studied by the SEM analysis, the results demonstrated that adsorption and wrapping between surfactant micelles and PFOA reduced the contact between PFOA and radicals and affected the surfactant effect on the surface tension.
- Subject
- perfluorooctanoic acids (PFOA); defluorination; ultrasound; persulfate; surfactant; radicals
- Identifier
- http://hdl.handle.net/1959.13/1479946
- Identifier
- uon:50419
- Identifier
- ISSN:1383-5866
- Language
- eng
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