Towards Zero-Waste PFAS Treatment Train: Regeneration of Ion Exchange Resins in Supercritical CO ₂ Coupled with Supercritical Water Oxidation
- 1University of Washington
- 2Aecom (United States)
Abstract
Ion-exchange resins (IXRs) are often used to remove PFAS from aqueous matrices; however, spent media generate secondary waste that must be disposed of. We demonstrate a waste-treatment strategy that combines IXR regeneration in a supercritical carbon dioxide (scCO 2 ) environment followed by destruction of PFAS-containing regenerants via supercritical water oxidation (SCWO). Screening of co-solvent formulation showed that HCl-amended ethanol/water mixture effectively extracted PFOA from both macroporous and gel-type resins marketed for single use. Macroporous IXR maintained sorbent capacity over five adsorption-regeneration cycles. Further optimization identified conditions for solvent reduction: an EtOH/H 2 O/HCl regenerant yielded regeneration efficiencies of ~97.6% for the gel-type and 99.7% for the macroporous resins within 60 minutes at flow rates corresponding to 9 BV. Comparison of the regenerant’s water content provided insights into the regeneration mechanism, progressing via (i) ion exchange in an H 2 O-rich hydration layer at the IXR surface followed by (ii) PFOA transport in the scCO 2 /EtOH-rich gas-like bulk flow. Downstream SCWO treatment of the regenerant shows complete PFOA defluorination. This treatment train advances sustainable PFAS management by combining sorbent reuse, reduced demand for non-toxic organic solvents, and end-of-life treatment of concentrated PFAS residuals.
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BibTeX
@misc{bai2026towards,
title = {{Towards Zero-Waste PFAS Treatment Train: Regeneration of Ion Exchange Resins in Supercritical CO ₂ Coupled with Supercritical Water Oxidation}},
author = {Shuyuan Bai and Almond Lau and Anmol L. Purohit and Mrityunjai Verma and Tatiana Didenko and Mohamed Ateia and Ji Feng and Igor Novosselov},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv-2026-kzxwg/v2},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv-2026-kzxwg/v2},
note = {CC BY},
}
RIS
TY - UNPB
TI - Towards Zero-Waste PFAS Treatment Train: Regeneration of Ion Exchange Resins in Supercritical CO ₂ Coupled with Supercritical Water Oxidation
AU - Shuyuan Bai
AU - Almond Lau
AU - Anmol L. Purohit
AU - Mrityunjai Verma
AU - Tatiana Didenko
AU - Mohamed Ateia
AU - Ji Feng
AU - Igor Novosselov
PY - 2026
DA - 2026/10/07
PB - ChemRxiv
DO - 10.26434/chemrxiv-2026-kzxwg/v2
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv-2026-kzxwg/v2
AB - Ion-exchange resins (IXRs) are often used to remove PFAS from aqueous matrices; however, spent media generate secondary waste that must be disposed of. We demonstrate a waste-treatment strategy that combines IXR regeneration in a supercritical carbon dioxide (scCO 2 ) environment followed by destruction of PFAS-containing regenerants via supercritical water oxidation (SCWO). Screening of co-solvent formulation showed that HCl-amended ethanol/water mixture effectively extracted PFOA from both macroporous and gel-type resins marketed for single use. Macroporous IXR maintained sorbent capacity over five adsorption-regeneration cycles. Further optimization identified conditions for solvent reduction: an EtOH/H 2 O/HCl regenerant yielded regeneration efficiencies of ~97.6% for the gel-type and 99.7% for the macroporous resins within 60 minutes at flow rates corresponding to 9 BV. Comparison of the regenerant’s water content provided insights into the regeneration mechanism, progressing via (i) ion exchange in an H 2 O-rich hydration layer at the IXR surface followed by (ii) PFOA transport in the scCO 2 /EtOH-rich gas-like bulk flow. Downstream SCWO treatment of the regenerant shows complete PFOA defluorination. This treatment train advances sustainable PFAS management by combining sorbent reuse, reduced demand for non-toxic organic solvents, and end-of-life treatment of concentrated PFAS residuals.
ER -