Ultrastable Co-NC membrane for sterilization of Escherichia coli in flowing water

Abstract

Advanced oxidation technology based on peroxonosulfate (PMS) has attracted extensive attention in water treatment research due to its fast reaction speed and wide pH range adaptability. Cobalt-based catalysts are considered to be one of the most effective reagents for PMS activation in various PMS activation methods. However, Co-ion leaching and difficulty in recovery have greatly hindered its practical applications. Herein, we developed a robust membrane constructed by nitrogen-doped carbon nanotubes embedded with cobalt nanoparticles (Co-NC) to concurrently address the Co-ion leaching and recovery issues. Based on our customization, continuous water flow reactor, the Co-NC membrane exhibited excellent catalytic activity and stability, in which it demonstrated a remarkable sterilization efficiency of 99.9999% against E. coli, and it retained a superior stability of 96.29% after 40 repeated cycles. Fewer attempts to put such efficient heterogeneous advanced oxidation processes (AOPs) into practical application, to mimic real-life applications, the performance of the Co-NC/PMS system was extended to the water taken from Qiuxi River. Remarkably, there is no deterioration in performance over 12 h of continuous real sewage processing. Mechanistic studies revealed that abundant high-valence metals (CoIV=O) were generated in the system, which can attack and penetrate into the cell membrane to destroy its intracellular defense system. This work provides useful insights into designing robust membranes with superior efficiency and stability for PMS-based advanced oxidation technology.