Occurrence of per- and poly-fluoroalkyl substances (PFASs) in the environment and biota has raised a great concern to public health because these compounds are persistent, bioaccumulative, and toxic. Biodegradation of polyfluoroalkyl substances, particularly long-chain fluorotelomer-based products, can lead to production of various short-chain PFASs, with 5:3 fluorotelomer carboxylic acid (referred as 5:3 FTCA hereafter) as a dominant polyfluoroalkyl metabolite. Perfluoroalkyl acids, particularly perfluorooctanoic acid (PFOA), are toxic and current removal methods are not cost-effective. This study reports the photodegradation of 5:3 FTCA and PFOA using ZnO as a photocatalyst under neutral pH and room temperature conditions. Under long UV wavelength (365 nm), both tetrapod and commercial ZnO can photodegrade 5:3 FTCA. Five removal products-perfluorohexanoic acid, perfluoropentanoic acid, perfluorobutyric acid, 5:2 fluorotelomer carboxylic acid (5:2 FTCA), and inorganic fluoride - were identified, with PFBA and F⁻ as dominant end products. SEM and XPS high resolution scans on the surface of the utilized ZnO showed less units of CF₂ than that in 5:3 FTCA, supporting occurrence of photodegradation of 5:3 FTCA by ZnO. Defluorination of PFOA was not observed with ZnO only, but at pH 5 and in the co-presence of Fe-citrate. PFOA defluorination increased from 0.93% after 3 days of UV light exposure to 3.9% after additional 135 h under direct sunlight exposure. To the authors’ best knowledge, this is the first report studying ZnO-catalyzed photodegradation of 5:3 FTCA, and examining the Fe co-addition for PFOA defluorination.

环境和生物区系中的全氟烷基物质和多氟烷基物质（PFAS）的存在已引起公众极大关注，因为这些化合物具有持久性，生物蓄积性和毒性。多氟烷基物质，特别是长链基于氟调聚物的产品的生物降解，可导致各种短链PFAS的生产，其中5：3氟调聚物羧酸（以下简称5：3 FTCA）为主要的多氟烷基代谢产物。全氟烷基酸，特别是全氟辛酸（PFOA），是有毒的，目前的去除方法并不具有成本效益。这项研究报告了在中性pH和室温条件下使用ZnO作为光催化剂对5：3 FTCA和PFOA的光降解。在长紫外波长（365 nm）下，四脚架和商用ZnO均可光降解5：3 FTCA。⁻作为主要最终产品。在所使用的ZnO表面进行SEM和XPS高分辨率扫描显示，与5：3 FTCA中的CF ₂单元相比，CF _2的单元数更少，这支持了ZnO对5：3 FTCA的光降解。不仅在ZnO上观察到PFOA的脱氟，在pH为5且柠檬酸铁共存的情况下也未观察到PFOA的脱氟。PFOA的脱氟从紫外线暴露3天后的0.93％增加到直接在阳光直射下另外135小时后的3.9％。据作者所知，这是第一份研究ZnO催化5：3 FTCA光降解并研究Fe共添加的PFOA脱氟的报告。