Mineralization of PTFE under conditions representative of municipal solid waste to energy incineration facilities

The objective of this study was to assess the effective mineralization of polytetrafluoroethylene (PTFE) during thermal treatment under municipal solid waste incinerator (MSWI) conditions and to evaluate the potential formation of per-and polyfluoroalkyl substances (PFAS) and select other products of incomplete destruction (PIDs). Analyses were performed on aqueous phase impinger samples (long chain PFAS under a modified EPA Method 537, and short chain C1-C3), as well as gas phase byproducts under OTM-50. A commercial grade PTFE sample was first subjected to elemental analyses and then incinerated in a bench-scale combustion system designed to represent conditions typical of MSWIs in the United States and European Union. Experimental system setpoints were chosen by computational fluid dynamic modeling and compared with an empirically measured temperature profile, to achieve a bulk material temperature as high as 1150°C and remain in the reactor for approximately 2 seconds. These parameters were informed by a comprehensive literature review of MSWI operating conditions. The experiment was run in triplicate and all instances demonstrated that all target analytes as non-detectable, or below the respective method reporting limit. In-line FTIR monitoring of hydrogen fluoride (HF) concentration achieved between 95.6 % and 97.4 % fluorine recovery, compared to between 79.0 % and 80.4 % fluorine recovery via aqueous fluoride-ion based calculations. Calculated destruction efficiency across the experiments averaged 99.99962 % for PTFE. These findings indicate that PTFE undergoes effective mineralization under typical incineration conditions, and that MSWI is a means of responsible end-of-life management for the fluoropolymer.