Although widely used in permeation reaction barrier (PRB) for strengthening the removal of various heavy metals,zero-valent iron (ZVI) is limited by various inherent drawbacks,such as easy passivation and poor electron transfer.As a solution,a synergistic system with PRB and electrokinetics (PRB-EK) was established and applied for the efficient removal of Cr(Ⅵ)-contaminated groundwaten As the filling material of PRB,ZVI/Fe3O4/activated carbon(ZVI/Fe3O4/AC) composites were synthesized by ball milling and thermal treatment.A se-ries of continuous flow column experiments and batch tests was conducted to evaluate the removal efficiency of Cr(Ⅵ).Results showed that the removal efficiency of Cr(Ⅵ) remained above 93％ even when the bed volume (BV) reached 2000 under the operational parameters(iron/AC mass ratio,2∶1;current,5 mA).The mechanism of Cr(Ⅵ) removal by the PRB-EK system was revealed through field emission scanning electron microscopy images,X-ray diffraction,X-ray photoelectron spectroscopy,Fe2+ concentration,and redox potential (Eh)values.The key in Cr(Ⅵ) reduction was the Fe2+/Fe3+ cycle driven by the surface microelec-trolysis of the composites.The application of an externally supplied weak direct current maintained the redox process by enhancing the electron transfer capability of the system,thereby prolonging the column lifetime.Cr(Ⅵ) chemical speciation was determined through sequential extraction,verifying the stability and safety of the system.These findings pro-vide a scientific basis for PRB design and the in-situ remediation of Cr(Ⅵ)-contaminated groundwater.

Ruolin Cao;Shiqing Liu;Xinyu Yang;Chunfeng Wang;Yanbin Wang;Wanfeng Wang;Yunqing Pi

Henan Key Laboratory for Environmental Pollution Control and Key Laboratory for Yellow River and Huai River Water Environment and Pollution Control (Ministry of Education),School of Environment,Henan Normal University,Xinxiang 453007,China

环境科学学报（英文版）

[1]Ruolin Cao;Shiqing Liu;Xinyu Yang;Chunfeng Wang;Yanbin Wang;Wanfeng Wang;Yunqing Pi-.Enhanced remediation of Cr(Ⅵ)-contaminated groundwater by coupling electrokinetics with ZVI/Fe3O4/AC-based permeable reactive barrier)[J].环境科学学报（英文版）,2022(02):280-290

electrokinetics,groundwaten,trolysis

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