Continuous efficient removal and inactivation mechanism of E. coli by bismuth-doped SnO/C electrocatalytic membrane.

The Bi-SnO/C electrocatalytic membrane was fabricated via a simple electrochemical reduction and hydrothermal method. Under the action of electric field, the Sn and Bi were firstly adsorbed and reduced to metallic Sn and Bi on the carbon membrane surface by cathodic reduction reaction, and the Bi-SnO/C membrane was obtained subsequently through hydrothermal oxidation process. Confirmed by SEM, TEM, XRD, and XPS characterizations, the nano-Bi-SnO is homogeneously distributed on the membrane surface and is firmly attached to the carbon membrane via C-O-Sn chemical bond. Through CV, LSV, and EIS electrochemical analysis, the Bi-SnO/C membrane possesses the higher electrocatalytic activity and stability than carbon membrane. Therefore, the Bi-SnO/C membrane could continuously efficiently remove and inactivate Escherichia coli in water through flow-through mode. As a result, the sterilization efficiency can reach more than 99.99% under the conditions of cell voltage 4 V, flow rate 1.4 mL/min, and E. coli initial concentration 1.0 × 10 CFU/mL, owing to the synergistic effect of the membrane separation and electrocatalytic oxidation. Moreover, it was found that the oxidation groups of ⋅OH radicals generated by Bi-SnO/C membrane play the crucial role for bactericidal performance. This work presents a low-cost, highly active, and stable electrocatalytic membrane towards continuous bacterial inactivation, which exhibits promising potential in water disinfection and is beneficial for practical large-scale applications.