Enhanced Degradation of Perfluorocarboxylic Acids (PFCAs) by UV/Sulfite Treatment: Reaction Mechanisms and System Efficiencies at pH 12,Environmental Science & Technology Letters

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Enhanced Degradation of Perfluorocarboxylic Acids (PFCAs) by UV/Sulfite Treatment: Reaction Mechanisms and System Efficiencies at pH 12
Environmental Science & Technology Letters ( IF 8.9 ) Pub Date : 2020-04-23 , DOI: 10.1021/acs.estlett.0c00236
Michael J. Bentel ₁ , Zekun Liu ₁ , Yaochun Yu _{1,

2} , Jinyu Gao ₁ , Yujie Men _{1,

2} , Jinyong Liu ₁

Affiliation

Reductive defluorination with UV-generated hydrated electrons (e_aq^–) is a promising technology for the destruction of perfluorocarboxylic acids (PFCAs, C_nF_2n+1COO^–). However, prior studies using pH 9–10 observed a slow reaction rate, limited defluorination percentage (deF%), and thus high energy consumption. Herein, we report on the substantially enhanced rate and extent of PFCA defluorination by operating the UV/sulfite system at the optimized pH 12. Degradation kinetics and transformation products show that at pH 12 the e_aq^– cleaved multiple strong C–F bonds that could not be cleaved at pH 9.5. The high pH condition also significantly favored the preferred decarboxylation pathway toward a deep defluorination. In comparison to the reactions at pH 9.5, the increase in solution pH to 12 improved the UV lamp energy efficiency by 5–22 folds, enhanced the deF% of C3–C9 PFCAs to 73%–93%, and reduced the overall consumption of chemicals.

中文翻译：

UV /亚硫酸盐处理增强的全氟羧酸（PFCA）降解：pH值为12时的反应机理和系统效率

还原脱氟用UV生成水合电子（ë_水溶液^-）是用于全氟羧酸的破坏（全氟羧酸，C有前途的技术_Ñ ˚F _{2 Ñ 1} COO ^-）。但是，先前使用pH 9-10进行的研究发现反应速度慢，脱氟百分率（deF％）有限，因此能耗高。在此，我们通过在优化的pH 12.降解动力学操作所述UV /亚硫酸盐系统上的显着增强PFCA脱氟的速率和程度报告，并转化产物表明，在pH值为12的ë_水溶液^-断裂了多个在pH 9.5时无法断裂的强CF键。高pH条件也显着促进了优选的脱羧途径，从而实现了深度脱氟。与pH 9.5时的反应相比，溶液pH值增加到12可将紫外线灯的能量效率提高5-22倍，将C3-C9 PFCA的deF％提高到73％-93％，并减少化学药品。

更新日期：2020-04-23

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