Michigan State University CCD-USA
Vanessa Maldonado is a 2nd year Ph.D. student in the Department of Chemical Engineering and Material Science at Michigan State University (MSU). She is an advocate of environmental protection. She is currently working on various projects related to PFAS water remediation including electrochemical oxidation of PFAS-impacted landfill leachates and plasma-treated carbon adsorption of PFOA in drinking water. This work is being developed at the Fraunhofer Center for Coatings and Diamond Technologies (CCD) at MSU.
Electrochemical Degradation of PFAS-impacted Landfill Leachates
Per and Poly-fluoroalkyl Substances (PFAS) are a group of synthetic chemicals with exceptional physicochemical properties which make them resistant to biodegradation. They have been identified as emerging environmental contaminants due to their recalcitrant nature and their associated high-risk health effects. Multiple consumer products containing PFAS end up in landfills, and their presence have been reported in landfill leachates in the ppb range. In addition, landfill leachates present multiple precursor compounds which can be further oxidized to the most common forms of PFAS: PFOA and PFOS.
We used electrochemical oxidation as a destructive technology to break down PFAS present in landfill leachates to non-detect levels.
A boron-doped diamond (BDD) electrode with an area/volume ratio of 16.8 cm2/L was used as the anode for the electrochemical oxidation of landfill leachates in a semi-batch system. The leachates were spiked with 20 ppb of PFOA and 20 ppb of PFOS.
Multiple current densities for the degradation of different PFAS present in the solutions were evaluated. Additional parameters including pH, temperature, conductivity, COD, ammonia, and chlorinated species were monitored over time. The results showed a percentage of degradation higher than 90 for both PFOA and PFOS after 2h of treatment. Non-detect levels of PFOS were reached after 6h of treatment with a current density equal or higher than 100 mA/cm2. The degradation of short chain-PFAS was also evaluated. In general, the degradation of sulfonic and carboxylic groups was independent and strongly dependent of the current density applied, respectively. The results of this study showed that electrochemical oxidation can be applied as an efficient treatment technology for PFASs degradation in real complex matrices.