Water and Remediation Catalog.

Authors: Bei Yan, Gabriel Munoz, Sébastien Sauvé, Jinxia Liu 

DOI: https://doi.org/10.1016/j.watres.2020.116166 

Synopsis:

• Smectite (Bentonite) clay with exchangeable interlayer sites, modified with organic functional groups has been demonstrated as an effective sorbent for real-world remediation of AFFF contaminated groundwater with removal efficiencies of 95-99%
• Notably, the removal efficiencies were not affected by common co-contaminants (BTEX, TCE, 1,4 Dioxane) nor water chemistry (Na⁺, Ca⁺) variations
• Sorption mechanisms were determined using molecular dynamics simulations where (1) negatively charged PFAS rapidly interact with the highly polarized outer edges of the clay, then (2) PFAS interact with the functionalized interlayer surface
• Both cationic intercalant sites for ionic interactions and lateral, fluorophilic interactions characterize the adsorption mechanism of the surface modified clay. Hydrophobic interactions of neutral PFAS with the modified clay were observed to be significant sorption mechanisms
• FLUORO-SORB® Adsorbent was observed to have comparable removal efficiencies to ion exchange resin (apart from ultra-short chain PFAS) and outperformed GAC in AFFF contaminated groundwater

Brief: Surface modified clay (SMC) has been demonstrated as a suitable remediation sorbent (95-99% removal) for PFAS contaminated groundwater, characterized by (a) ionic, (b) fluorophilic, and (c) hydrophobic interactions both at the polarized edges and within the interlayers of the SMC. Unlike other commonly used sorbents, SMC is found to be resistant to impacts of co-contaminants within the environment.