The process and mechanism of pulse electrolytic oxidation of ciprofloxacin antibiotic in wastewater on boron-doped diamonds

A novel process and method for treating ciprofloxacin (CIP) antibiotic wastewater using pulsed electrooxidation at boron-doped diamond (BDD) electrodes have been developed to address the issues of low efficiency and high energy consumption associated with traditional electrochemical oxidation methods. The effects of pulsed direct current (PDC), pulsed alternating current (PAC), and direct current (DC) on chemical oxygen demand (COD) removal were studied. It was found that complete degradation of CIP could be achieved within 45 min using PAC. COD removal reached 92.4% after 90 min of PAC electrooxidation for 90 mg·dm−3 CIP wastewater under optimized conditions of current density (j) = 30 mA·cm−2, initial pH (pH0) = 3, sodium sulfate concentration (c(Na2SO4)) = 50 mmol·dm−3, and frequency (f) = 100 Hz. The electrical energy consumption (EEC) was found to be 35 W·h·dm−3. The CIP degradation followed a quasi-first order kinetic law. The degradation pathway was found to involve hydroxylation of the quinolone moiety, cleavage of the piperazine ring, and fluorine substitution (OH/F substitution). The results showed that PAC electrochemical oxidation at all-BDD electrodes exhibited the highest removal efficiency and lowest EEC for CIP removal. This study provides a novel and effective approach for the efficient treatment of CIP antibiotic wastewater using bidirectional pulse current at all-BDD electrodes.