Complete Defluorination and Mineralization of Perfluorooctanoic Acid by a Mechanochemical Method Using Alumina and Persulfate
| Autor: | Yuqi Zhou, Heqing Tang, Yue Hu, Hanqing Lv, Nan Wang, Tetsuro Majima, Lihua Zhu |
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| Rok vydání: | 2019 |
| Předmět: |
Fluorocarbons
Hydroxyl Radical Decarboxylation Hydrogen bond General Chemistry Potassium persulfate 010501 environmental sciences Photochemistry Persulfate 01 natural sciences Mineralization (biology) chemistry.chemical_compound chemistry Aluminum Oxide Environmental Chemistry Perfluorooctanoic acid Hydroxyl radical Caprylates Bond cleavage 0105 earth and related environmental sciences |
| Zdroj: | Environmental Science & Technology. 53:8302-8313 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/acs.est.9b00486 |
| Popis: | Perfluorooctanoic acid (PFOA) is a persistent organic pollutant that has received concerns worldwide due to its extreme resistance to conventional degradation. A mechanochemical (MC) method was developed for complete degradation of PFOA by using alumina (Al2O3) and potassium persulfate (PS) as comilling agents. After ball milling for 2 h, the MC treatment using Al2O3 or PS caused conversion of PFOA to either 1-H-1-perfluoroheptene or dimers with a defluorination efficiency lower than 20%, but that using both Al2O3 and PS caused degradation of PFOA with a defluorination of 100% and a mineralization of 98%. This method also caused complete defluorination of other C3∼C6 homologues of PFOA. The complete defluorination of PFOA attributes to Al2O3 and PS led to the weakening of the C-F bond in PFOA and the generation of hydroxyl radical (•OH), respectively. During the MC degradation, Al2O3 strongly anchors PFOA through COO--Al coordination and in situ formed from Lewis-base interaction and PS through hydrogen bond. Meanwhile, mechanical effects induce the homolytic cleavage of PS to produce SO4•-, which reacts with OH group of Al2O3 to generate •OH. The degradation of PFOA is initiated by decarboxylation as a result of weakened C-COO- due to Al3+ coordination. The subsequent addition of •OH, elimination of HF, and reaction with water induce the stepwise removal of all carboxyl groups and F atoms as CO2 and F-, respectively. Thus, complete defluorination and mineralization are achieved. |
| Databáze: | OpenAIRE |
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