Iron slag permeable reactive barrier for PFOA removal by the electrokinetic process

Namuun Ganbat; Faris M Hamdi; Ibrar Ibrar; Ali Altaee; Lilyan Alsaka; Akshaya K Samal; John Zhou; Alaa H Hawari

doi:10.1016/j.jhazmat.2023.132360

Iron slag permeable reactive barrier for PFOA removal by the electrokinetic process

J Hazard Mater. 2023 Oct 15:460:132360. doi: 10.1016/j.jhazmat.2023.132360. Epub 2023 Aug 22.

Authors

Namuun Ganbat¹, Faris M Hamdi¹, Ibrar Ibrar¹, Ali Altaee², Lilyan Alsaka¹, Akshaya K Samal³, John Zhou¹, Alaa H Hawari⁴

Affiliations

¹ Centre for Green Technology, School of Civil and Environmental Engineering, University of Technology Sydney, Australia.
² Centre for Green Technology, School of Civil and Environmental Engineering, University of Technology Sydney, Australia. Electronic address: ali.altaee@uts.edu.au.
³ Centre for Nano and Material Sciences, Jain University, Ramanagara, Bangalore 562 112, Karnataka, India.
⁴ Department of Civil and Architectural Engineering, College of Engineering, Qatar University, PO Box 2713, Doha, Qatar.

PMID: 37657326
DOI: 10.1016/j.jhazmat.2023.132360

Abstract

The efficacy of the Standalone Electrokinetic (EK) process in soil PFAS removal is negligible, primarily due to the intersecting mechanisms of electromigration and electroosmosis transportation. Consequently, the redistribution of PFAS across the soil matrix occurs, hampering effective remediation efforts. Permeable reactive barrier (PRB) has been used to capture contaminants and extract them at the end of the EK process. This study conducted laboratory-scale tests to evaluate the feasibility of the iron slag PRB enhanced-EK process in conjunction with Sodium Cholate (NaC) biosurfactant as a cost-effective and sustainable method for removing PFOA from the soil. A 2 cm iron slag-based PRB with a pH of 9.5, obtained from the steel-making industry, was strategically embedded in the middle of the EK reactors to capture PFOA within the soil. The main component of the slag, iron oxide, exhibited significant adsorption capacity for PFOA contamination. The laboratory-scale tests were conducted over two weeks, revealing a PFOA removal rate of more than 79% in the slag/activated carbon PRB-EK test with NaC enhancement and 70% PFOA removal in the slag/activated carbon PRB-EK without NaC. By extending the duration of the slag/AC PRB-EK test with NaC enhancement to three weeks, the PFOA removal rate increased to 94.09%, with the slag/AC PRB capturing over 87% of the initial PFOA concentration of 10 mg/L. The specific energy required for soil decontamination by the EK process was determined to be 0.15 kWh/kg. The outcomes of this study confirm the feasibility of utilizing iron slag waste in the EK process to capture PFOA contaminants, offering a sustainable approach to soil decontamination. Combining iron slag PRB and NaC biosurfactant provides a cost-effective and environmentally friendly method for efficient PFOA removal from soil.

Keywords: Electrokinetic; Enhanced Electrokinetic; PFAS treatment; Permeable reactive barrier; Soil remediation.