Norfloxacin mineralization under light exposure using Sb-SnO2 ceramic anodes coated with BiFeO3 photocatalyst

Advanced Oxidation Processes have been proven to be an efficient way to remove organic pollutants from wastewaters. In this work, a ceramic electrode of Sb-SnO2 (BCE) with a layer of the photocatalytic material BiFeO3 (BFO-BCE), has been characterized electrochemically and further tested for norfloxacin photo-electrooxidation in the presence and absence of light. The electrode photoactivity was highly enhanced thanks to the presence of BiFeO3, as confirmed by Linear Sweep Voltammetry, chronoamperometry and potentiometry, and Electrochemical Impedance Spectroscopy. Additionally, working in galvanostatic mode, a high minerali-zation of norfloxacin was achieved after 240 min, reaching 62% at 25 mA cm-2 under light conditions. This value is comparatively higher than the 40% achieved with the BCE. The oxidation byproducts were followed by ionic chromatography and HPLC analysis, which also allowed us to propose an oxidation pathway of the norfloxacin molecule. Finally, some indicators of the reactor performance such as the Mineralization Current Efficiency and the specific energy consumption were analyzed, revealing that lower current densities (8.3 mA cm-2) led to higher current efficiencies, and that light improved both the current efficiency and energy consumption.

Automated summary

Advanced Oxidation Processes are efficient for removing organic pollutants from wastewaters. This study characterized a ceramic electrode with a photocatalytic layer, BiFeO3, and tested it for norfloxacin oxidation with and without light. The electrode's photoactivity was significantly enhanced by BiFeO3, resulting in higher mineralization of norfloxacin under light conditions. The oxidation pathway of norfloxacin was proposed based on analysis of oxidation byproducts. The study also analyzed reactor performance indicators and showed that lower current densities and light improved current efficiency and energy consumption.