Electrochemical degradation of antibiotic enoxacin using a novel PbO2 electrode with a graphene nanoplatelets inter-layer: Characteristics, efficiency and mechanism

A novel PbO(2)electrode was fabricated by adding graphene nanoplatelets (GNP) inter-layer into beta-PbO2 active layer (called GNP-PbO2) and utilized to degradation of antibiotic enoxacin (ENO). The GNP-PbO2 electrode had a much rougher surface than the typical PbO2 electrode, with smaller crystal size and lower charge-transfer resistance at the electrode/electrolyte interface. Notably, the GNP inter-layer increased the oxygen evolution potential of PbO2 electrode (2.05 V vs. SCE), which was very beneficial to inhibit oxygen evolution and promote .OH production. The relatively best operating parameters for ENO removal and energy efficiency were current density of 20 mA cm(-2), initial pH of 7, initial ENO concentration of 100 mg L-1 and electrode distance of 4 cm. Furthermore, indirect radical oxidation was found to be the main way during electrolysis process. Based on the observed analysis of intermediate products, the main reaction pathways of ENO included hydroxylation, defluorination and piperazine ring-opening. Finally, combinating with the electro-oxidation capability, stability and safety evaluation, we can conclude that GNP-PbO2 is a promising anode for treatment of various organic pollutants in wastewater.

Automated summary

In this study, a novel PbO2 electrode was fabricated by adding graphene nanoplatelets (GNP) inter-layer and utilized for degradation of antibiotic enoxacin. The experimental results showed that the electrode had a rough surface, smaller crystal size, and lower charge-transfer resistance, which could effectively inhibit oxygen evolution and promote .OH production. Under certain operating parameters, the electrode could efficiently remove enoxacin.