ElektroDeHalo
Perfluorinated surfactants (PFT) have oil and water repellent properties and are therefore used in the textile industry for hydrophobation and oleophobization processes. All PFTs are chemically stable and non-biodegradable, which is why they accumulate in the environment as well as in animals and humans. Presently, water contaminated with PFT is purified in multi-stage processes using activated carbon, which adsorbs the PFT and is then thermally regenerated. Water purification with activated carbon requires large volumes and thus considerably exceeds the costs of traditional purification processes with limited efficiency. Up to date, there is no commercial process that separates PFT and degrades it completely on site. The electrochemical degradation of PFT by anodic oxidation is therefore being intensively researched. The aim of this project is to develop an efficient, two-stage water treatment process for the removal and decomposition of PFTs. PFTs will first be electroadsorbed on a porous carbon electrode and then electrochemically degraded on site in a second step. By separating adsorption and decomposition over time, the process can be carried out continuously when several modules are used. A microtubular carbon gas diffusion electrode developed at DWI is suitable both as an adsorbent and as an electrode material. By applying a positive potential, the anionic PFTs can be electroadsorbed. In the second step, the PFTs are desorbed by reversing the electrode potential and/or thermally. At the same time, the decomposition of the pollutant is started by anodic oxidation on a boron-doped diamond electrode. At the gas diffusion electrode, the electro-Fenton process, which is based on the formation of hydroxyl radicals, takes place simultaneously, thereby supporting the decomposition of the resulting intermediate products and accelerating the overall process. The research includes the following steps: investigation of the electroadsorption and electrodesorption behaviour, test of the compatibility of the anodic oxidation and the electro-Fenton process.