Near-100% fluorine recovery from PTFE and PFAS
A team from Nagoya Institute of Technology, Japan, claim up to 98% fluorine recovery from PTFE and PFAS at room temperature.
The scientists say that sodium dispersion for polytetrafluoroethylene (PTFE) and per- and polyfluoroalkyl substances (PFAS) overcomes the limitations of traditional high-energy or high-temperature defluorination processes.
Landfilling leads to an environmental burden of undegraded PTFE, the team reports.
By contrast, defluorination, in which PTFE is converted into its constituent fluorine compounds, is eco-friendly as it enables polymer recycling. They say traditional PTFE defluorination either requires high-temperature reactions above 500°C, or complex reagents for the more manageable low-temperature reactions below 100°C.
Their method reportedly yields sodium fluoride from PTFE using sodium dispersion in tetrahydrofuran at 25°C over 12 hours.
Spectral analysis of the PTFE degradation under optimised conditions using spectral analysis, estimates the proportion of fluoride lost from PTFE to be 93.5%.
The defluorination process transforms PTFE’s morphology, from an initial dense, irregularly shaped grainy texture with smooth surfaces into a black residue with a highly irregular rough surface showing cracks.
The technique can also recover up to 97% fluorine from PFAS, highlight the researchers - namely perfluorononanoic acid, perfluorooctanoic acid, perfluorobutanesulfonic acid and trifluoroacetic acid - once the reaction duration and sodium dispersion quantity are properly fine-tuned.
