Anthony Rappé
Professor
Colorado State University
Dr. Anthony Rappe is a Professor in the Department of Chemistry at Colorado State University. He holds a PhD in Chemistry from Caltech as well as a BS in Chemistry from the University Puget Sound. Dr. Rappe’s research revolves around using theoretical tools to study chemical reactivity. Over the years he has studied deNOx catalysis, nitrogen activation, hydrocarbon oxidation, olefin polymerization, and photoredox processes involving earth abundant catalysts. He has also been involved in methods development including the UFF force field. Dr. Rappe is currently working on computational studies to help manage PFASs.
Incineration of Perfluoroalkyl Carboxylic Acids:
A Thermal Stability Ranking Among Common Organic Chemicals
Anthony K. Rappé1, Robert Giraud2,3, Jens Blotevogel4
1 Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
2 The Chemours Company, Wilmington, DE 19899, USA
3 Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
4 CSIRO, Glen Osmond, SA 5064, Australia
Thermal treatment processes are currently the only option for the destruction of per- and polyfluoroalkyl substances (PFAS) in large waste streams. Due to the lack of robust data on thermal PFAS decomposition, concerns about the formation and emission of products of incomplete combustion (PICs) exist. To determine the required conditions for safe incineration, we performed uniquely accurate quantum chemical simulations to assess the thermal decomposition pathways and kinetics of perfluorooctanoic acid (PFOA) and its replacement hexafluoropropylene oxide dimer acid (HFPO-DA). Considering all relevant thermal decomposition mechanisms, we calculated temperatures at 2 second gas residence time indicative of 99.99% destruction and removal efficiency (DRE) for full-scale incineration. Our findings show that initial incineration of these two perfluoroalkyl carboxylic acids (PFCAs) requires substantially lower temperatures than several other organic compounds that are being incinerated on a regular basis. No increase in required incineration temperature was observed with decreasing length of the perfluoroalkyl chain, indicating a low potential for PIC accumulation under the right conditions. However, as some decomposition processes were found to be concentration-dependent, waste stream composition plays a key role in thermal decomposition rates. Collectively, our findings will provide critically missing information to ensure safe, cost-efficient, and complete destruction of PFCAs during thermal treatment.
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