Periodically reversing electrocoagulation technique for efficient removal of short-chain perfluoroalkyl substances from contaminated groundwater around a fluorochemical facility

Yang Liu; Meng-Yuan Lu; Jia Bao; Li-Xin Shao; Wen-Jing Yu; Xiao-Min Hu; Xin Zhao

doi:10.1016/j.chemosphere.2023.138953

Periodically reversing electrocoagulation technique for efficient removal of short-chain perfluoroalkyl substances from contaminated groundwater around a fluorochemical facility

Chemosphere. 2023 Sep:334:138953. doi: 10.1016/j.chemosphere.2023.138953. Epub 2023 May 15.

Authors

Yang Liu¹, Meng-Yuan Lu², Jia Bao³, Li-Xin Shao⁴, Wen-Jing Yu⁵, Xiao-Min Hu⁶, Xin Zhao⁶

Affiliations

¹ School of Environmental and Chemical Engineering, Shenyang University of Technology, Shenyang, 110870, China. Electronic address: liuyang@sut.edu.cn.
² School of Environmental and Chemical Engineering, Shenyang University of Technology, Shenyang, 110870, China.
³ School of Environmental and Chemical Engineering, Shenyang University of Technology, Shenyang, 110870, China. Electronic address: baojia@sut.edu.cn.
⁴ School of Mechanical Engineering, Shenyang University of Technology, Shenyang, 110870, China.
⁵ School of Water Resources & Environment, China University of Geosciences, Beijing, 100083, China.
⁶ School of Resources and Civil Engineering, Northeastern University, Shenyang, 110819, China.

PMID: 37196788
DOI: 10.1016/j.chemosphere.2023.138953

Abstract

Widespread distributions of short-chain perfluoroalkyl substances (PFASs) has been recognized as a crucial environmental issue. However, multiple treatment techniques were ineffective due to their high polarity and mobility, contributing to a never-ending existence in the aquatic environment ubiquitously. The present study revealed potential technique of periodically reversing electrocoagulation (PREC) to perform efficient removal of short-chain PFASs including experimental factors (in the conditions of 9 V for voltage, 600 r/min of stirring speed, 10 s of reversing period, and 2 g/L of NaCl electrolyte), orthogonal experiments, actual application, and removal mechanism. Accordingly, based upon the orthogonal experiments, the removal efficiencies of perfluorobutane sulfonate (PFBS) in simulated solution could achieve 81.0% with the optimal parameters of Fe-Fe electrode materials, addition of 665 μL H₂O₂ per 10 min, and pH at 3.0. The PREC was further applied for treating the actual groundwater around a fluorochemical facility, consequently the removal efficiencies for typical short-chain perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), PFBS, and perfluoropentane sulfonate (PFPeS) were 62.5%, 89.0%, 96.4%, 90.0%, and 97.5%, respectively. The other long-chain PFASs contaminants had superior removal with the removal efficiencies up to 97%-100%. In addition, a comprehensive removal mechanism related to electric attraction adsorption for short-chain PFASs could be verified through the morphological analysis of ultimate flocs composition. The oxidation degradation was further revealed as the other removal mechanism by suspect and nontarget screening of intermediates formed in simulated solution, as well as density functional theory (DFT) calculation theory. Moreover, the degradation pathways about one CF₂O molecule or CO₂ eliminated with one C atom removed in PFBS by ·OH generated from the PREC oxidation process were further proposed. As a result, the PREC would be a promising technique for the efficient removal of short-chain PFASs from severely contaminated water bodies.

Keywords: Electric attraction; Groundwater; Periodically reversing electrocoagulation (PREC); Removal mechanism; Short-chain perfluoroalkyl substances (PFASs).

MeSH terms

Electrocoagulation
Fluorocarbons* / analysis
Groundwater* / chemistry
Hydrogen Peroxide / analysis
Water Pollutants, Chemical* / analysis

Substances

Water Pollutants, Chemical
Hydrogen Peroxide
Fluorocarbons
perfluorobutanesulfonic acid