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Measurement of Fluorinated and Other Volatile Compounds from Incomplete PFAS Destruction in Incineration Using FTIR Spectroscopy
Citation:
Dunder, T., Jonathan D. Krug, AND W. Roberson. Measurement of Fluorinated and Other Volatile Compounds from Incomplete PFAS Destruction in Incineration Using FTIR Spectroscopy. AWMA Air Quality Measurements, RTP, NC, March 08 - 10, 2022.
Impact/Purpose:
This presentation will focus on the potential utility of Fourier Transform Infrared (FTIR) spectroscopy in verifying PFAS compound destruction by incineration systems. Measurements were performed on the Rainbow Furnace in EPA’s RTP facilities, where model PFAS refrigerant compounds (CF4, C2F6, and CHF3) and Acqueous Film Forming Foam (AFFF) were fed into the furnace through the flame as well as through several post-flame positions at various firing rates, temperatures and residence times. FTIR can measure a wide range of volatile fluorine-containing organic compounds including to analyze stack gas for investigation of products of incomplete combustion. The presentation's first author is Thomas Dunder, Technical Director of TRC Companies and possessing over thirty years of expertise in the application of FTIR to measurements of air emissions from stationary sources. This work represents unique applications of applied combustion science, where 1) experiments were performed using model compounds in a real combustion system, real-time measurements were performed of the injected compound; and 2) PFAS containing liquid was injected into an incinerator under controlled conditions, and targetted and non-targetted samples were collected for analysis of destruction and formation of products of incomplete combustion. This represents a significant potential enhancement in knowledge regarding sampling methodologies in the thermal treatment of PFAS-containing waste. This abstract was internally reviewed by an ORD researcher and will be sent to the AWMA Air Quality Measurements conference for external review.
Description:
PFAS contamination of soil and water has been identified throughout the United States. One source is the use of PFAS-containing Aqueous Film-Forming Foams (AFFFs) used at airports, military bases, industrial facilities, and elsewhere to respond to fire emergencies as well as to train fire-fighting personnel. As PFAS contamination is being surveyed, and the use of PFAS containing AFFFs are being re-evaluated and new formulations are developed, many legacy formulations that contain perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are being directed for disposal. The result is a significant amount of PFAS-containing AFFF that must be disposed of safely. Although not currently designated as a hazardous waste, AFFF is often sent to commercial hazardous waste incinerators for disposal. While other disposal and destructive technologies are under development, measurements must be developed to verify complete destruction, including compounds formed from incomplete destruction. In the case of incineration, complete destruction is total conversion (“mineralization”) of PFAS compounds to hydrogen fluoride (HF) and carbon dioxide (CO2). Given the strength of the C-F chemical bond, compounds such as CF4 and C2F6 may be created, the detection of which demonstrates incomplete destruction. In experiments conducted by scientists at the U.S. EPA, AFFF was combusted in a pilot-scale refractory-lined natural gas-fired furnace and the breakdown products were measured by FTIR spectroscopy. FTIR can measure a wide range of volatile fluorine-containing organic compounds as well as HF. The AFFF was injected under varying conditions to evaluate the effects of flame chemistry, stoichiometry, temperature and residence time on destruction and formation of indicator compounds. The presentation focuses on the potential utility of FTIR in verifying PFAS destruction in incineration systems. This research was partially funded by U.S. Environmental Protection Agency (EPA). The views expressed in this abstract are those of the authors and do not necessarily represent the views and policies of the U.S. EPA.