Peroxymonosulfate enhanced photoelectrocatalytic degradation of ofloxacin using an easily coated cathode

This study described a promising photoelectrocatalytic (PEC) system enhanced by peroxymonosulfate (PMS) for the treatment of ofloxacin in wastewater. The PEC system, which employed a BiVO4 as photoanode and a polydopamine modified carbon felt (PDA/CF) as cathode, was constructed. The PDA/CF cathode was easily prepared by a dopamine self-polymerization process. The effect of PMS concentrations, applied potential and initial solution pH on the ofloxacin degradation was investigated in the enhanced PEC system. Ofloxacin can be completely removed after 120 min reaction under the optimal conditions of applied potential 1.5 V, pH 5.0 and 2 mM PMS addition. Based on the electron spin resonance measurement, sulfate radicals (SO4 center dot-), hydroxyl radicals ((OH)-O-center dot) and singlet oxygen (O-1(2)) were mainly responsible for ofloxacin degradation. Analyses of the degradation intermediates indicated that the C-N bond, piperazine ring and the fluoride group of ofloxacin were attacked in its degradation process. The introduction of dopamine on the cathode significantly enhanced the PMS activation to produce active radicals, which further improved the ofloxacin degradation. The possible mechanism was proposed for ofloxacin degradation in the PEC system enhanced by the addition of PMS.