Environmental Sciences Group, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, Canada.
Department of Civil Engineering, Queen's University, Kingston, ON, Canada.
Sci Total Environ. 2022 Aug 20;835:155506. doi: 10.1016/j.scitotenv.2022.155506. Epub 2022 Apr 26.
There is a need for destructive technologies for per- and polyfluoroalkyl substances (PFAS) in soil. While planetary ball mill have been shown successful degradation of PFAS, there are issues surrounding scale up (maximum size is typically 0.5 L cylinders). While having lower energy outputs, horizontal ball mills, for which scale up is not a limiting factor, already exist at commercial/industrial sizes from the mining, metallurgic and agricultural industries, which could be re-purposed. This study evaluated the effectiveness of horizontal ball mills in degrading perfluorooctanesulfonate (PFOS), 6:2 fluorotelomer sulfonate (6:2 FTSA), and aqueous film forming foam (AFFF) spiked on nepheline syenite sand. Horizontal ball milling was also applied to two different soil types (sand dominant and clay dominant) collected from a firefighting training area (FFTA). Liquid chromatography tandem mass spectrometry was used to track 21 target PFAS throughout the milling process. High-resolution accurate mass spectrometry was also used to identify the presence and degradation of 19 non-target fluorotelomer substances, including 6:2 fluorotelomer sulfonamido betaine (FtSaB), 7:3 fluorotelomer betaine (FtB), and 6:2 fluorotelomer thioether amido sulfonate (FtTAoS). In the presence of potassium hydroxide (KOH), used as a co-milling reagent, PFOS, 6:2 FTSA, and the non-target fluorotelomer substances in the AFFF were found to undergo upwards of 81%, 97%, and 100% degradation, respectively. Despite the inherent added complexity associated with field soils, better PFAS degradation was observed on the FFTA soils over the spiked NSS, and more specifically, on the FFTA clay over the FFTA sand. These results held through scale-up, going from the 1 L to the 25 L cylinders. The results of this study support further scale-up in preparation for on-site pilot tests.
需要开发针对土壤中全氟和多氟烷基物质（PFAS）的破坏性技术。虽然行星球磨机已成功降解 PFAS，但在扩大规模方面存在问题（最大尺寸通常为 0.5 L 圆柱形容器）。虽然水平球磨机的能量输出较低，但在采矿、冶金和农业等行业，已经存在可用于扩大规模的商业/工业尺寸的水平球磨机，这些球磨机可以重新用于降解 PFAS。本研究评估了水平球磨机在降解全氟辛烷磺酸（PFOS）、6:2 氟代烷烃磺酸盐（6:2 FTSA）和添加到霞石正长岩砂中的水性成膜泡沫（AFFF）方面的有效性。水平球磨也应用于从消防训练区（FFTA）收集的两种不同土壤类型（砂为主和粘土为主）。液相色谱串联质谱法用于跟踪整个球磨过程中的 21 种目标 PFAS。高分辨率精确质量质谱法还用于鉴定存在和降解 19 种非目标氟代烷烃物质，包括 6:2 氟代烷烃磺酰胺甜菜碱（FtSaB）、7:3 氟代烷烃甜菜碱（FtB）和 6:2 氟代烷烃硫醚酰胺磺酸盐（FtTAoS）。在作为共磨试剂的氢氧化钾（KOH）的存在下，发现 PFOS、6:2 FTSA 和 AFFF 中的非目标氟代烷烃物质分别经历了超过 81%、97%和 100%的降解。尽管与现场土壤相关的固有复杂性增加，但在 FFTA 土壤上观察到的 PFAS 降解情况要好于添加 NSS 的土壤，特别是在 FFTA 粘土上要好于 FFTA 砂上。这些结果通过从 1 L 到 25 L 圆柱形容器的放大得到了验证。本研究的结果支持进一步放大规模，为现场试点试验做准备。
