Employment of TiO2 Meshes Electrochemical Photocatalysis for the Degradation of Emerging Organic Pollutants in Wastewater Effluents

Electrochemical TiO2 photocatalysis is an innovative and rather unknown method of advanced oxidation processes (AOP) for water treatment. The photoactive coating is grown directly on titanium wire meshes. It shows good mechanical adhesion to the substrate and good electrical conductivity. During the wastewater treatment step aimed at removing organic pollutants, an electrical bias can be effectively applied to the catalyst through the wire mesh, leading to a synergistic effect with UV light and a faster degradation kinetics with respect to either photocatalytic or the electrochemical process. Photoactive TiO2 coatings are obtained by a number of techniques including sol-gel, CVD, RF Magnetron Sputtering, Plasma Spray, Electron Beam Evaporation, Anodic Oxidation [1] and Plasma Electrolytic Oxidation (PEO) [2]. In the present study, the catalyst was obtained by Plasma Electrolytic Oxidation. Various studies over recent years have proved the increasing occurrence in effluent of wastewater treatment plants (WWTP) of several contaminants of emerging concern (CECs), which are not completely removed by the common technologies employed in conventional WWTP. CECs found at highest levels (ng/L to ?g/L) are pharmaceuticals, artificial sweeteners, pesticides, flame-retardants, plasticizers and perfluoroalkyl substances. In the present study, the effectiveness of the aforementioned UV-based AOP for CECs removal was explored by investigating the decontamination of aqueous solutions containing the pharmaceutical drug carbamazepine, which is one of the main CEC in municipal wastewaters. The process was carried out in a laboratory-scale tubular photocatalytic reactor working in semi-batch mode under electrical polarization of the catalyst. The UV source consisted of a 30 W UV-C lamp emitting at 254 nm.