Session: Innovative & Practical Approaches for the Treatment of Per- & Polyfluoroalkyl Substances (PFASs):

Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals used in various commercial industries to include food packaging, non-stick repellent, and waterproof products [1]. The Environmental Protection Agency (EPA) is currently looking for methods to safely dispose of PFAS waste, to include incineration [1]. Incineration disposes of chemicals by breaking chemical bonds at high temperatures, upwards of over 1000 °C to 1400 °C [1]. Incineration has been used to dispose of other related compounds, but PFAS compounds present a challenge for breakdown due to the high electronegativity of fluorine [1]. Research on the efficacy of this method is currently limited, as it is unknown yet what happens when smaller PFAS are formed or when undesirable products form due to partial combustion [1]. In this study, the incineration products for polymer gaskets made from polytetrafluorethylene (PTFE) known as Teflon^TM, vinylidene difluoride/hexafluoropropylene copolymer (Viton A, and Viton B), poly(vinylidene fluoride-co-hexa-fluoropropylene) PVDF-HFP, and polychlorotrifluoroethylene (Kel-F 800) are analyzed. Thermoanalytical methods, such as Thermomechanical Analysis (TMA), Thermogravimetric Analysis-Mass Spectrometry (TGA-MS) and Differential Scanning Calorimetry (DSC), are used for characterizing thermal degradation of the fluoropolymers. Moreover, mass spectral data via TGA-MS assist in identification of thermal degradation products that are desorbed or formed from thermal break down during the TGA heating process. Moreover, chemical characterization through Fourier-Transform Infrared Spectroscopy (FTIR) is used to identify differences in chemical functional groups within the polymers before and after combustion at the identified temperature ranges. Solid residues from TMA, DSC and TGA are examined via Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) to identify surface morphology and elemental changes after thermal degradation. This information will be used to develop a proposed mechanism of degradation for each of the analyzed fluorinated compounds. This data will help further the understanding of the initial oxidation and combustion of the polymers themselves up to 200 °C, together with the high temperature degradation (>1000 °C) of the post-combustion products.

Bryan Lagasse

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