Electrochemical Studies of Perfluoroacids (PFAs) and Perfluorooctane Sulfonate (PFOS)
Discipline: Ecology Environmental and Earth Sciences
Subcategory: Chemistry (not Biochemistry)
Session: 2
Room: Hoover
Brianna Kenney - Delaware State University
Co-Author(s): Co-Authors: Bizuneh Workie, Delaware State University, DE; Endalkachew Sahle-Demessie, US Environmental Protection Agency, OH
Per- and polyalkyl compounds (PFCs) are anthropogenic industrial compounds used in many applications, including surface coatings, surfactants, and flame retardants. They are, however, emerging contaminants due to their recalcitrant nature; persistence in air, water, and soil environments. PFCs have been detected in water and soil samples all over the globe, as well as in humans and in wildlife. Decomposition of PFCs using oxidation or reduction methods could produce new treatment approaches. We use cyclic voltammetry (CV) to determine if the PFAs and PFOS are electrochemically active. We also use chronoamperometry to determine if exhaustive electrolysis is an effective method in treating PFCs in water. The studies were conducted in acetonitrile (CH3CN) with tetrabutylammonium hexafluorophosphate (TBAHFP) as a supporting electrolyte using a CH Instruments Electrochemical Analyzer, Model 660A. CV studies of 5.00 mM solution of all the PFAs, PFOA, and PFOS in the range of 0.50 V and -1.20 V using platinum working and Ag/AgCl, KCl(satd.) reference electrodes showed that the compounds are reducible and have the same number of major cathodic and anodic peaks, and the same overall appearances with shifts in the peak potentials and variation in the peak heights. Exhaustive electrolysis of 25 mL of 5.0 mM of PFOA in TBAHFP?CH3CN at a potential of -1.450 V vs. Ag/AgCl,KCl(satd.) showed an almost complete reduction of PFOA in 1 hr. These studies support the possibility of new electrochemical treatment methods of PFCs. Further studies will be conducted to study the electroreduction mechanism and use the information obtained to develop an electrochemical method for the decomposition of PFAs, PFOA, and PFOS in water.
Funder Acknowledgement(s): I thank the Delaware State University Bridge to the Doctorate Program, DSU Professional Development Program, and Delaware State University Delaware Institute for Science and Technology for their help and financial support.
Faculty Advisor: Bizuneh Workie, bworkie@desu.edu
Role: I conducted the experiments in the lab, including preparing the solutions, running the cyclic voltammetry and the exhaustive electrolysis of the different PFAs.