Reactive electrochemical ceramic membrane filtration system for efficient treatment of enrofloxacin from wastewater: Mechanisms and applications

A novel reactive electrochemical ceramic membrane (RECM), assembled by ceramic membrane and reduced TiO2 nanotube arrays (rTNA) based PbO2 membrane anode with a Sb-SnO2 interlayer (rTNA/Sb-SnO2/PbO2), was developed in this study with the dual functions of low-pressure membrane filtration and efficient removal of antibiotics from wastewater. Compared with Ti/Sb-SnO2 and rTNA/Sb-SnO2 membrane anodes, rTNA/Sb-SnO2/ PbO2 anode exhibited higher oxygen evolution potential, larger active surface area and promising electrochemical stability, owing to the introduction of rTNA structure and PbO2 layer. The rTNA/Sb-SnO2/PbO2 RECM also achieved a higher electrochemical degradation performance than Ti/Sb-SnO2 and rTNA/Sb-SnO2 RECMs, as well as a lower energy consumption. The antibiotic enrofloxacin (ENR) removal of the rTNA/Sb-SnO2/PbO2 RECM in the flow-through mode was 5.4 times higher than that in the flow-by mode. These results were ascribed to the improved mass transfer of ENR towards anode surface and reactive oxygen species (i.e., H2O2, O2 center dot-, and center dot OH) production. According to theoretical computations and the detection results of intermediates, the degradation pathway involved the defluorination, hydroxylation, decarboxylation, and breakage of quinolone and/or piperazine rings of ENR under the attack of hydroxyl radicals in the RECM system. The findings demonstrated the application potential of the rTNA/Sb-SnO2/PbO2 RECM in removing ENR from wastewater.