State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, PR China.
Sci Total Environ. 2020 Nov 10;742:140438. doi: 10.1016/j.scitotenv.2020.140438. Epub 2020 Jun 23.
Perfluoroalkyl substance (PFAS) is a class of anionic surfactants with superior stability in the environment. Due to the harmful health effect, PFASs have been listed as the priority controlled pollutants. Our recent study had developed a cationic surfactant induced ternary self-assembled micelle system to effectively degrade PFASs. In this study, using perfluorooctanoic acid (PFOA) as the model pollutant, we further investigated the effects of different variables on the degradation processes. According to the results of laser flash photolysis and dynamic light scattering, the degradation of PFOA was positively correlated with the chain length of the surfactants. While for double-chain surfactant, the steric effect might hinder the reaction. Our results also indicated that in the presence of high concentration of NaCl, the electrostatic attraction between Cl and the positively charged micelle made the micelle structure loose and thus slightly reduced the degradation efficiency. Similarly, the presence of NOM could also affect the degradation process via regulating the micelle structure. Furthermore, the optimal degradation efficiency for PFOA was obtained at neutral pH by the compromise of hydrated electron yield and self-assembled micelle structure. This composite showed good adaptability under ambient conditions and would have great potential for treatment of industrial PFAS containing wastewater, e.g., in the ternary micelle system, 18.95 mg L PFOA could be completely degraded within 8 h without any pretreatments.
全氟烷基物质 (PFAS) 是一类阴离子表面活性剂，在环境中具有优异的稳定性。由于对健康有害，PFAS 已被列为优先控制的污染物。我们最近的研究开发了一种阳离子表面活性剂诱导的三元自组装胶束体系，可有效降解 PFAS。在这项研究中，我们以全氟辛酸 (PFOA) 为模型污染物，进一步研究了不同变量对降解过程的影响。根据激光闪光光解和动态光散射的结果，PFOA 的降解与表面活性剂的链长呈正相关。而对于双链表面活性剂，空间位阻效应可能会阻碍反应。我们的结果还表明，在高浓度 NaCl 存在下，Cl 和带正电荷胶束之间的静电吸引使胶束结构松散，从而略微降低了降解效率。类似地，NOM 的存在也可以通过调节胶束结构来影响降解过程。此外，通过水合电子产率和自组装胶束结构的折衷，在中性 pH 下可获得 PFOA 的最佳降解效率。该复合体系在环境条件下具有良好的适应性，有望用于处理工业 PFAS 废水，例如，在三元胶束体系中，18.95mg/L 的 PFOA 在无需任何预处理的情况下可在 8 小时内完全降解。
