Continuous H2O2 production sustained by anodic O2 for the destruction of the antibiotic ampicillin by photoelectro-Fenton process in a rotating cylinder electrode reactor

In this work, the experimental characterization of a rotating cylinder electrode (RCE) reactor employed for the complete degradation of the antibiotic ampicillin (AMP) by photoelectro-Fenton (PEF) process has been addressed for the first time. Once produced from water oxidation at six Ti|IrO2 anodic plates, O2 was quickly transported by forced convection toward the central RCE, which consisted of a 316 stainless-steel cylinder covered with a (C-PTFE)-coated carbon cloth, thus ensuring the continuous production of H2O2 from the two-electron O2 reduction reaction (ORR). The accumulated H2O2 reached a concentration of 83.3 mg L−1 H2O2 after 60 min in a 50 mM Na2SO4 solution at pH 3, operating at an RCE peripheral velocity U = 79.6 cm s−1 and fixed cathodic potential of Ecath = −0.45 V vs. SHE. Furthermore, the optimum PEF conditions led to the complete destruction of 10 mg L−1 AMP in only 10 min upon addition of 0.4 mM Fe2+ as catalyst under UVA light irradiation, with a low electrolytic energy consumption of 0.211 kWh (g TOC)−1. In addition, the evolution of final carboxylic acids and inorganic ions over the electrolysis time was monitored by chromatographic and spectrophotometric techniques. PEF treatment clearly outperformed the anodic oxidation with (AO-H2O2) and the electro-Fenton (EF) processes, which opens the door to a sustainable and powerful electrochemical technology with no need for an air compressor for H2O2 production and viable under limitless sunlight irradiation.