Poly- and perfluoroalkyl substances (PFASs) are a large group of persistent chemicals that have been used in industrial processes and commercial products for over 60 years. For example, perfluorooctanesulfonic acid (PFOS) is one of the most persistent, toxic and bioaccumulative contaminants from the EU Directive 2013/39/EU list of priority substances. PFOS and related chemicals are refractory to currently applied advanced chemical oxidation processes (e.g., ozonation, UV/H2O2). Available technologies for the removal of PFASs from water - activated carbon, ion exchange and reverse osmosis - are inefficient for more toxic, short-chain perfluorinated compounds, and are highly affected by the background organic matter. More importantly, these technologies do not destroy the contaminants but merely transfer them to another medium.
In this project, we are developing novel anode materials based on carbon and metal-based nanomaterials, for electrochemical removal of PFAS from water. We are focused on the two main groups of materials: 1) TiO2 nanotube array (NTA)-based anodes, and 2) graphene sponge electrodes. Graphene sponge electrodes are of particular interest for the PFAS removal as they are a porous, three-dimensional material that is highly hydrophobic and offer a high surface area for PFAS adsorption, do not produce any chlorine, and can be tailored to enhance the removal of polar, short-chain PFAS via electrosorption. After ensuring the interaction between the PFAS and the electrode surface, they can be completely defluorinated and transformed into innocuous, fluorine-free byproducts.