Removal of sodium perfluorononyloxybenzenesulfonate (OBS) as an emerging PFAS contaminant from aquatic environments by magnetic ultrafine hydrotalcite adsorption-CPAM coagulation technique: Combined performance and mechanism

Yuqing Yang; Siyi Zu; Liqiu Zhang; Yongze Liu; Jie Jin; Ziwen Du

doi:10.1016/j.watres.2025.123792

Removal of sodium perfluorononyloxybenzenesulfonate (OBS) as an emerging PFAS contaminant from aquatic environments by magnetic ultrafine hydrotalcite adsorption-CPAM coagulation technique: Combined performance and mechanism

Water Res. 2025 May 7:283:123792. doi: 10.1016/j.watres.2025.123792. Online ahead of print.

Authors

Yuqing Yang¹, Siyi Zu¹, Liqiu Zhang¹, Yongze Liu¹, Jie Jin², Ziwen Du³

Affiliations

¹ Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; China Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
² MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China.
³ Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China; China Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China. Electronic address: ziwendu@bjfu.edu.cn.

PMID: 40349599
DOI: 10.1016/j.watres.2025.123792

Abstract

The demand for effective remediation of aqueous per- and polyfluoroalkyl substances (PFAS), especially emerging PFAS, has constantly increased over the last few years. Although adsorption and coagulation are well-established techniques for PFAS remediation, adsorption reaction requires a long equilibrium time; coagulation performance deteriorates when PFAS concentration becomes lower. To address the challenges, an integrated approach which synergistically combined adsorption and coagulation was proposed in this study, using perfluorononenoxybenzenesulfonate (OBS) as the target emerging PFAS to evaluate performance. Ultrafine magnetic hydrotalcite (Fe₃O₄@LDHs), synthesized via a simple ball-milling process, served as the adsorbent in this approach. Such ultrafine material not only enhanced floc formation during coagulation but also showed rapid OBS adsorption via anion exchange. Cationic Polyacrylamide (CPAM) as the optimal coagulant contributed to OBS removal through electrostatic attraction driven by [R₄N⁺] groups and hydrophobic interactions involving its alkyl chains. Under optimal dosage of CPAM (25 mg·L^-1) and Fe₃O₄@LDHs (50 mg·L^-1), the combined magnetic coagulation process achieved 99.89 % of OBS removal within 30 mins. Such combined method still showed effective performance in the presence of hydrocarbon organic competitors, achieving above 90 % removal of OBS from firefighting training wastewater with an acceptable dosing increase. The adsorption-coagulation technique provides a promising and fast solution for treating PFAS wastewater, such as firefighting and industrial wastewater.

Keywords: AFFF wastewater; Magnetic coagulation; Modified IDHs; OBS; PFASS.