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Use of Volatile Fluorinated Compounds as Indicators of Thermal Treatment Effectiveness for PFAS
Citation:
Krug, J., W. Roberson, E. Shields, P. Lemieux, W. Linak, Rucker Burnette, S. McDonald, G. Whitfield, AND W. Preston. Use of Volatile Fluorinated Compounds as Indicators of Thermal Treatment Effectiveness for PFAS. 40th International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors, Charlotte, NC, September 13 - 14, 2023.
Impact/Purpose:
EPA’s Office of Research and Development performed a series of experimental studies using a pilot-scale down-fired natural gas combustor to examine the thermal destruction of per and poly-fluorinated alkyl substances (PFAS). Testing was performed on four distinct PFAS containing formulations of Aqueous Film Forming Foam (AFFF) concentrates at a range of furnace injection temperatures indicative of incomplete mineralization. In addition to AFFF, injections of volatile fluorinated compounds (VFCs; i.e., CHF3, C2F6, and C3F8) were performed individually and concurrently with AFFF injections to ascertain if they are indicators of thermal treatment performance of other PFAS compounds. Quantitative recoveries of the VFCs were achieved by Fourier infrared spectroscopy (FTIR), accompanied with dynamic spiking with VFC. In addition, application of an in-development canister sampling method for analysis of volatile, non-polar PFAS compounds was used to evaluate formation of selected fluorinated products of incomplete combustion (PICs) from each of the AFFF mixtures. Species and concentrations of PICs were compared as a function of injection temperature and parent PFAS species in the liquid AFFF concentrates. Finally, the various PIC formations were compared to the apparent destruction efficiency (DE) of the injected refrigerant compounds to determine if there is correlation between AFFF PIC formations and the DE of potential surrogate compounds. This presentation will discuss the current experimental program, measurement techniques for both FTIR and canister sampling methods, experimental results from EPA’s pilot-scale combustor (including the formation and nature of PICs), and future research plans.
Description:
EPA’s Office of Research and Development performed a series of experimental studies using a pilot-scale down-fired natural gas combustor to examine the thermal destruction of per and poly-fluorinated alkyl substances (PFAS). Testing was performed on four distinct PFAS containing formulations of Aqueous Film Forming Foam (AFFF) concentrates at a range of furnace injection temperatures indicative of incomplete mineralization. In addition to AFFF, injections of volatile fluorinated compounds (VFCs; i.e., CHF3, C2F6, and C3F8) were performed individually and concurrently with AFFF injections to ascertain if they are indicators of thermal treatment performance of other PFAS compounds. Quantitative recoveries of the VFCs were achieved by Fourier infrared spectroscopy (FTIR), accompanied with dynamic spiking with VFC. In addition, application of an in-development canister sampling method for analysis of volatile, non-polar PFAS compounds was used to evaluate formation of selected fluorinated products of incomplete combustion (PICs) from each of the AFFF mixtures. Species and concentrations of PICs were compared as a function of injection temperature and parent PFAS species in the liquid AFFF concentrates. Finally, the various PIC formations were compared to the apparent destruction efficiency (DE) of the injected refrigerant compounds to determine if there is correlation between AFFF PIC formations and the DE of potential surrogate compounds. This presentation will discuss the current experimental program, measurement techniques for both FTIR and canister sampling methods, experimental results from EPA’s pilot-scale combustor (including the formation and nature of PICs), and future research plans.