Enhancement of electrocatalytic activity for micropollutant removal by CeO2@CNT-based membranes: The influences of the structure and morphology of CeO2

It is important to develop novel electrocatalytic membranes for efficiently remove micropollutants from water and wastewater. In this study, two CeO2 samples (denoted as CeO2-N and CeO2-O, respectively) were synthesized to modify the carbon nanotube (CNT)-based membrane. CeO2-N exhibited a higher proportion of Oad and Olat to the formation of Ov. In contrast, CeO2-O possessed a cubic cerianite structure with less Ov. As a result, the CeO2-N@CNT-based membrane displayed a smaller equivalent polarization resistance of 5.6 Ω/cm2 and lower potential differences of 0.19 V compared to the CeO2-O@CNT-based membrane, which had an equivalent polarization resistance of 6.9 Ω/cm2 and potential differences of 0.51V. Consequently, the CeO2-N@CNT-based membrane demonstrated superior performance in diclofenac (DCF) removal compared to the CeO2-O@CNT-based membrane. Due to its planes with lower apparent activation energy and higher single electron transfer rate, the CeO2-N@CNT-based membrane generated a greater amount of 1O2. Conversely, the CeO2-O@CNT-based membrane generated more ·OH. Therefore, DCF mainly underwent degradation via C-N bond cleavage and decarboxylation through direct attack of 1O2 for the CeO2-N@CNT-based membrane, while ·OH played a significant role in removing DCF via hydrogen loss, chlorine loss and C-N cleavage for the CeO2-O@CNT-based membrane.