Photoelectrocatalytic oxidation of chlortetracycline using Ti/TiO2 photo-anode with simultaneous H2O2 production

Abstract

This study investigated the photoelectrocatalytic oxidation (PECO) of chlortetracycline (CTC) in aqueous solution using a Ti/TiO2 photocatalyst. The Ti/TiO2 used as photo-anode was prepared by a pulsed laser deposition (PLD) method. The PLD TiO2 coatings were found to have rutile and anatase structures consisting of nano-crystallites of approximately 10nm and 15nm in diameter, respectively. The influence of various parameters such as crystallographic structure of Ti/TiO2, cathode material and pH were evaluated. Experimental results revealed that a current intensity of 0.39A under UV irradiation (245nm) for a period of treatment of 120min was beneficial for CTC oxidation. The initial CTC concentration (25μg/L) could be optimally diminished up to 98.0±0.2% while using a Ti/TiO2 photo-anode having a crystallographic structure of anatase and using vitreous carbon as cathode. Under these conditions, a relatively high mineralization of CTC (67.3±2.15% of TOC removal and 69.3±3.10% of TN removal) was recorded. The initial rate of photoelectrocatalytic degradation of CTC can be well described by the Langmuir–Hinshelwood (L–H) kinetic model (R2=0.9996) with a reaction rate constant of 17.3μg/Lmin. Likewise, microtox (Vibrio fisheri), microalga (Pseudokirchneriella Subcapitata) and Daphnia (Daphnia magna) biotests revealed that the treated – effluent was not toxic compared to the untreated effluent.