Electrochemical degradation of ciprofloxacin using a coupled 3D anode to a microfluidic flow-through reactor

Abstract

In this study, the performance of a 3D mixed metal oxide anode (Ti/RuO2IrO2) produced by hybrid heating using microwaves for the electrochemical oxidation of ciprofloxacin (0.06 mmol L−1) was studied in a microfluidic flow-through reactor (MF-reactor) and an electrochemical batch reactor (Reactor-3D). A comparison with a 2D anode of the same composition was also performed in an electrochemical batch reactor (Reactor-2D) to evaluate the efficiency of using 3D anodes. Physical and electrochemical characterizations were performed to observe the properties of the anodes under study. The effects of current density and electrolyte concentration were evaluated. The 3D anode showed superior electrocatalytic properties to the 2D anode due to its high surface area (3.1 times increase). It showed a 3.8 times reduction in charge transfer resistance, making it unnecessary to apply high currents for complete antibiotic removal. The process in the MF-reactor presented the lowest energy consumption among the reactor configurations, with a lower ohmic loss due to the smaller distance between the electrodes. Under optimized conditions: 0.06 mol L−1 NaCl and 20 mA cm−2, the photo-assisted electrochemical (PAEC) degradation was also studied in MF-reactor. The PAEC in the MF-reactor proved to be a good combination of processes for degrading CIP, achieving complete degradation in 1 h (k = 0.1755 min−1), while in the EO process, it was achieved in 2 h (k = 0.1523 min−1). The MF-reactor can be an excellent option for degrading recalcitrant organic compounds such as ciprofloxacin.