Calcium Metal Mechanochemically Defluorinates PFAS to Environmentally Benign CaF2.
4 affiliations
- 1School of Chemistry, University of Birmingham, BirminghamB15 2TT, U.K.
- 2Birmingham Centre for Mechanochemistry and Mechanical Processing, University of Birmingham, BirminghamB15 2TT, U.K.
- 3Facility for Electron Microscopy, University of Birmingham, BirminghamB15 2TT, U.K.
- 4School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon TyneNE1 7RU, U.K.
Abstract
Fluoropolymers and other per- and polyfluoroalkyl substances (PFAS) are among the most persistent anthropogenic materials. Although bulk fluoropolymers such as polytetrafluoroethylene (PTFE) are often regarded as chemically inert, weathering and abrasion generate long-lived fluorinated microplastics, while molecular PFAS accumulate in the environment as mobile contaminants. Existing destruction strategies can cleave C-F bonds, but typically require incineration or aggressive reagents and frequently generate water-soluble fluoride products that remain environmentally problematic. Here we show that calcium metal enables solvent-free mechanochemical defluorination of PTFE and perfluorooctanoic acid (PFOA) at ambient starting temperature without external heating, while irreversibly sequestering fluorine as calcium fluoride, a nontoxic, insoluble, and environmentally benign solid. Quantitative solid-state 19F NMR, with detection limits explicitly assessed, shows no resolvable PTFE after 30 min of milling with Ca and Mg (<1.0% residual PTFE); Sr gives near-complete conversion (<10% residual PTFE), whereas Ba gives only partial (∼64% residual PTFE) conversion after 30 min of milling. TEM and SEM-EDX reveal CaF2-rich nanocrystalline domains intimately mixed with an oxygen-containing disordered carbonaceous material. By coupling efficient defluorination with fluoride sequestration, this work establishes a mechanochemical strategy for mineralization of persistent fluorinated materials without generating soluble alkali-metal fluoride waste as a secondary environmental hazard, while defining the analytical and process-safety constraints relevant to further development.
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BibTeX
@article{simbari2026calcium,
title = {{Calcium Metal Mechanochemically Defluorinates PFAS to Environmentally Benign CaF2.}},
author = {Luis Simbari and Moosa Wasim and Anže Zupanc and Shrestha Banerjee and Benjamin M Gallant and Joshua Deakin and Francisco Alvarado Cesar and Roly J Armstrong and Tomislav Friščić and Erli Lu and Dominik J Kubicki},
journal = {Journal of the American Chemical Society},
year = {2026},
month = oct,
doi = {10.1021/jacs.6c11635},
url = {https://europepmc.org/article/MED/42913542},
note = {CC BY},
}
RIS
TY - JOUR
TI - Calcium Metal Mechanochemically Defluorinates PFAS to Environmentally Benign CaF2.
AU - Luis Simbari
AU - Moosa Wasim
AU - Anže Zupanc
AU - Shrestha Banerjee
AU - Benjamin M Gallant
AU - Joshua Deakin
AU - Francisco Alvarado Cesar
AU - Roly J Armstrong
AU - Tomislav Friščić
AU - Erli Lu
AU - Dominik J Kubicki
PY - 2026
DA - 2026/10/01
JO - Journal of the American Chemical Society
DO - 10.1021/jacs.6c11635
UR - https://europepmc.org/article/MED/42913542
AB - Fluoropolymers and other per- and polyfluoroalkyl substances (PFAS) are among the most persistent anthropogenic materials. Although bulk fluoropolymers such as polytetrafluoroethylene (PTFE) are often regarded as chemically inert, weathering and abrasion generate long-lived fluorinated microplastics, while molecular PFAS accumulate in the environment as mobile contaminants. Existing destruction strategies can cleave C-F bonds, but typically require incineration or aggressive reagents and frequently generate water-soluble fluoride products that remain environmentally problematic. Here we show that calcium metal enables solvent-free mechanochemical defluorination of PTFE and perfluorooctanoic acid (PFOA) at ambient starting temperature without external heating, while irreversibly sequestering fluorine as calcium fluoride, a nontoxic, insoluble, and environmentally benign solid. Quantitative solid-state 19F NMR, with detection limits explicitly assessed, shows no resolvable PTFE after 30 min of milling with Ca and Mg (<1.0% residual PTFE); Sr gives near-complete conversion (<10% residual PTFE), whereas Ba gives only partial (∼64% residual PTFE) conversion after 30 min of milling. TEM and SEM-EDX reveal CaF2-rich nanocrystalline domains intimately mixed with an oxygen-containing disordered carbonaceous material. By coupling efficient defluorination with fluoride sequestration, this work establishes a mechanochemical strategy for mineralization of persistent fluorinated materials without generating soluble alkali-metal fluoride waste as a secondary environmental hazard, while defining the analytical and process-safety constraints relevant to further development.
SN - 0002-7863
SN - 1520-5126
ER -