Abstract
Per- and polyfluoroalkyl substances (PFAS) are an emergent threat to the environment due to their toxic, carcinogenic, and environmentally persistent nature. Commonly, these harmful micropollutants are removed from contaminated water sources through adsorption by porous sorbents such as activated carbon. While studies suggest a relationship between sorbent pore size and their PFAS remediation performance, the underlying mechanisms—particularly those related to sorbate morphology—have not been elucidated through direct experimental observations. This work investigates how pore size in carbonaceous sorbents impacts the morphology of adsorbed perfluorooctanoic acid (PFOA) aggregates and their sorption behavior, using microporous and mesoporous carbons as models. Contrast-matching small-angle neutron scattering (CM-SANS) is used to determine the structure of adsorbed PFOA molecules, supported by molecular dynamics simulations and physisorption experiments. Our findings reveal that the larger pore sizes in mesoporous sorbents enable the formation of PFOA assemblies during adsorption, which is hindered in microporous sorbents. Collectively, this work provides direct insights into the adsorption and assembly mechanisms of PFAS molecules within confined pores, offering important insights for the rational design of effective remediation systems.
| Original language | English |
|---|---|
| Pages (from-to) | 2935-2944 |
| Number of pages | 10 |
| Journal | Materials Horizons |
| Volume | 12 |
| Issue number | 9 |
| DOIs | |
| State | Published - Feb 18 2025 |
Funding
M. R. would like to acknowledge funding support through the DOE SCGSR program. Z. Q. and A. G. acknowledge the support from NSF CMMI-2239408. This research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The beam time was allocated to CG2 on proposal number IPTS-31802, IPTS-30935, IPTS-31100, IPTS-28612. The authors would also like to acknowledge HPC at The University of Southern Mississippi. HPC is supported by the National Science Foundation under the Major Research Instrumentation (MRI) program via Grant # ACI 1626217.