Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Sci Total Environ. 2020 Jun 1;719:137372. doi: 10.1016/j.scitotenv.2020.137372. Epub 2020 Feb 18.
Advanced oxidation and reduction processes have been intensively investigated as potential methods to promote the decomposition of perfluoroalkyl substances (PFASs). However, extreme operational conditions such as highly acidic pH, high temperature, and high pressure are required to promote degradation reactions, which makes these technologies costly and less feasible for full-scale applications. The objective of this study was to evaluate the effectiveness of zero-valent iron (ZVI) alone and a mixture of ZVI and biochar (ZVI + BC) for removal of seven target PFASs from water under ambient environmental conditions. Target PFASs included three perfluoroalkyl carboxylic acids (PFCAs) [perfluorooctanoic acid (PFOA, C8-PFCA), perfluoroheptanoic acid (C7-PFCA), and perfluorohexanoic acid (C6-PFCA)] and four perfluoroalkyl sulfonic acids (PFSAs) [perfluorooctane sulfonic acid (PFOS, C8-PFSA), perfluoroheptane sulfonic acid (C7-PFSA), perfluorohexane sulfonic acid (C6-PFSA), and perfluorobutane sulfonic acid (C4-PFSA)]. Batch test results show that PFSAs (up to 94% removal) were more effectively removed than PFCAs (up to 60% removal) when utilizing either ZVI or (ZVI + BC). About 20-60% of input PFOA (18,550 μg L) and 90-94% of input PFOS (18,580 μg L) were removed by ZVI alone or the mixture of (ZVI + BC). The removal efficiencies of PFCAs and PFSAs by reactive media increased with increasing chain length, from 0 to 17% for short-chain PFCAs (C6-C7) and 20 to 70% for short-chain PFSAs (C4-C7). About 5-10% of input PFOA and PFOS was partially defluorinated by ZVI alone as indicated by F release; however, the defluorination efficiency may be underestimated due to the sorption of F by the reactive media. Overall, the reactive mixture (ZVI + BC) may be an effective and environmentally sustainable material for removing PFASs from water under ambient environmental conditions.
高级氧化还原工艺已被广泛研究，作为促进全氟烷基物质 (PFASs) 分解的潜在方法。然而，为了促进降解反应，需要极端的操作条件，如高度酸性 pH 值、高温和高压，这使得这些技术成本高昂，不太适用于大规模应用。本研究的目的是评估零价铁 (ZVI) 单独使用以及 ZVI 和生物炭混合物 (ZVI+B C) 在环境条件下从水中去除七种目标 PFAS 的效果。目标 PFASs 包括三种全氟烷基羧酸 (PFCAs) [全氟辛酸 (PFOA，C8-PFCA)、全氟庚酸 (C7-PFCA) 和全氟己酸 (C6-PFCA)] 和四种全氟烷基磺酸 (PFSAs) [全氟辛烷磺酸 (PFOS，C8-PFSA)、全氟庚烷磺酸 (C7-PFSA)、全氟己烷磺酸 (C6-PFSA) 和全氟丁烷磺酸 (C4-PFSA)]。批次测试结果表明，当使用 ZVI 或 (ZVI+B C) 时，PFSAs(高达 94%的去除率)比 PFCAs(高达 60%的去除率)更有效地去除。通过单独的 ZVI 或 (ZVI+B C)，输入的 PFOA(约 18550μg/L)的 20-60%和输入的 PFOS(约 18580μg/L)的 90-94%被去除。反应介质对 PFCAs 和 PFSAs 的去除效率随链长的增加而增加，从短链 PFCAs(C6-C7)的 0 到 17%和短链 PFSAs(C4-C7)的 20 到 70%。通过单独的 ZVI，输入的 PFOA 和 PFOS 的约 5-10%部分脱氟，这表明 F 的释放；然而，由于反应介质对 F 的吸附，脱氟效率可能被低估。总的来说，反应混合物 (ZVI+B C) 可能是一种有效且环境可持续的材料，可用于在环境条件下从水中去除 PFASs。
