Emerging conductive ceramic membranes for water purification and membrane fouling mitigation

As a water purification strategy, electrochemically coupled ceramic membrane separation (ECMS) has attracted growing research interests in various water treatment applications due to its in-situ cleaning of fouling, sustainability, and high removal of refractory pollutants. We first describe the current state of research, conductive ceramic membranes (CCMs) materials, and synthesis methods. Next, we highlight the membrane interfacial reaction mechanisms of CCMs and the impact of critical parameters in water purification applications. Additionally, we analyze membrane fouling types, influencing factors, and blockage models. Finally, based on the limitations of the existing studies, we make recommendations for future research and applications. Summarizing the discussion, we identified Semiconductor material-loaded CCMs (S-CCMs) as the most promising CCMs regarding cost (material cost and preparation cost), efficacy, and technology maturity. The Janus membrane design concept utilizes both sides of the CCM as the cathode and anode, greatly reducing reactor complexity and increasing energy efficiency. Further, electro-oxidation, electro-evolutionary bubbling, and electro-repulsion at the membrane interface are the main in-situ self-cleaning mechanisms. Current density and membrane flux are crucial parameters for ECMS in the water purification process as they affect the efficacy of contaminant removal. We suggest that a combined blockage model based on the principle of energy head loss in describing the membrane blockage process is optimum. Overall, the review provides essential guidance for CCMs to reduce fabrication costs and improve water purification efficiency.