Dong Dengpan, Kancharla Samhitha, Hooper Justin, Tsianou Marina, Bedrov Dmitry, Alexandridis Paschalis
Department of Materials Science and Engineering, University of Utah, 122 South Central Campus Drive, Room 304, Salt Lake City, UT 84112, USA.
Phys Chem Chem Phys. 2021 Apr 28;23(16):10029-10039. doi: 10.1039/d1cp00049g.
Surface active per- and polyfluoroalkyl substances (PFAS) released in the environment generate great concern in the US and worldwide. The sequestration of PFAS amphiphiles from aqueous media can be limited by their strong tendency to form micelles that plug the pores in the adsorbent material, rendering most of the active surface inaccessible. A joint experimental and simulation approach has been used to investigate the structure of perfluorooctanoate ammonium (PFOA) micelles in aqueous solutions, focusing on the understanding of ethanol addition on PFOA micelle formation and structure. Structurally compact and slightly ellipsoidal in shape, PFOA micelles in pure water become more diffuse with increasing ethanol content, and break into smaller PFOA clusters in aqueous solutions with high ethanol concentration. A transition from a co-surfactant to a co-solvent behavior with the increase of ethanol concentration has been observed by both experiments and simulations, while the latter also provide insight on how to achieve co-solvent conditions with other additives. An improved understanding of how to modulate PFAS surfactant self-assembly in water can inform the fate and transport of PFAS in the environment and the PFAS sequestration from aqueous media.
环境中释放的表面活性全氟和多氟烷基物质（PFAS）在美国乃至全球引起了广泛关注。从水介质中螯合PFAS两亲物可能会受到限制，因为它们极易形成胶束，从而堵塞吸附材料中的孔隙，使大部分活性表面无法被利用。本研究采用实验与模拟相结合的方法，研究了全氟辛酸铵（PFOA）在水溶液中的胶束结构，重点研究了乙醇添加对PFOA胶束形成和结构的影响。PFOA胶束在纯水中结构紧凑，呈略椭圆形，随着乙醇含量的增加，其结构变得更加分散，并在高乙醇浓度的水溶液中分解为较小的PFOA簇。实验和模拟均观察到，随着乙醇浓度的增加，乙醇从助表面活性剂转变为助溶剂，模拟还深入探讨了如何使用其他添加剂达到助溶剂条件。深入了解如何调节PFAS表面活性剂在水中的自组装，有助于了解PFAS在环境中的归宿和迁移，以及从水介质中螯合PFAS的方法。
