Aminated clay-polymer composite as soil amendment for stabilizing the short- and long-chain per- and poly-fluoroalkyl substances in contaminated soil

Rahim Shahrokhi; Aneesu Rahman; Martin A Hubbe; Junboum Park

doi:10.1016/j.jhazmat.2024.134470

Aminated clay-polymer composite as soil amendment for stabilizing the short- and long-chain per- and poly-fluoroalkyl substances in contaminated soil

J Hazard Mater. 2024 Jul 5:472:134470. doi: 10.1016/j.jhazmat.2024.134470. Epub 2024 May 3.

Authors

Rahim Shahrokhi¹, Aneesu Rahman², Martin A Hubbe³, Junboum Park⁴

Affiliations

¹ Department of Civil and Environmental Engineering, Seoul National University, Seoul, South Korea. Electronic address: shahrokhishahraki@snu.ac.kr.
² Department of Civil and Environmental Engineering, Seoul National University, Seoul, South Korea.
³ Department of Forest Biomaterials, North Carolina State University, NC, United States.
⁴ Department of Civil and Environmental Engineering, Seoul National University, Seoul, South Korea; Institute of Construction and Environmental Engineering, Seoul National University, Seoul, South Korea. Electronic address: junbpark@snu.ac.kr.

PMID: 38714051
DOI: 10.1016/j.jhazmat.2024.134470

Abstract

Soils contaminated with per- and poly- fluoroalkyl substances (PFAS) require immediate remediation to protect the surrounding environment and human health. A novel animated clay-polymer composite was developed by applying polyethyleneimine (PEI) solution onto a montmorillonite clay-chitosan polymer composite. The resulting product, PEI-modified montmorillonite chitosan beads (MMTCBs) were characterized as an adsorptive soil amendment for immobilizing PFAS contaminants. The MMTCBs exhibited good efficiency to adsorb the PFAS, showing adsorption capacities of 12.2, 16.7, 18.5, and 20.8 mg g^-1 for PFBA, PFBS, PFOA, and PFOS, respectively, which were higher than those obtained by granular activated carbon (GAC) (i.e., an adsorbent used as a reference). Column leaching tests demonstrated that amending soil with 10% MMTCBs resulted in a substantial decrease in the leaching of PFOA, PFOS, PFBA, and PFBS by 90%, 100%, 64%, and 68%, respectively. These reductions were comparable to the values obtained for GAC-modified soil, particularly for long-chain PFAS. Incorporating MMTCBs into the soil not only preserved the structural integrity of the soil matrix but also enhanced its shear strength (kPa). Conversely, adding GAC to the soil resulted in a reduction of the soil's mechanical properties.

Keywords: GAC; MMTCBs; Montmorillonite; PFAS; Sorption.