Constructing fast mass-transfer channels with efficient catalytic ozonation activity in 2D manganese dioxide membranes by intercalating Fe/Mn bimetallic MOF

Abstract

Two-dimensional (2D) catalytic ozonation membranes are promising for the treatment of micropollutants in wastewater due to simultaneous ozone-catalyzed degradation and membrane filtration processes. However, it remains challenging for 2D catalytic ozonation membranes to efficiently degrade micropollutants due to low mass-transfer efficiency and poor catalytic activity. Herein, Fe/Mn bimetallic metal–organic framework (MOF) intercalated lamellar MnO₂ membranes with fast and robust ozone-catalyzed mass-transfer channels were developed on the surface of the hollow fiber ceramic membrane (HFCM) to obtain 2D Fe/Mn-MOF@MnO₂-HFCM for efficiently degrading micropollutants in wastewater. The intercalation of Fe/Mn-MOF expanded the interlayer spacing of the MnO₂ membrane, thereby providing abundant transport channels for rapid passage of water. More notably, the Fe/Mn-MOF provided enriched reactive sites as well as high electron transfer efficiency based on the redox cycling between Mn³⁺/Mn⁴⁺ and Fe²⁺/Fe³⁺, ensuring the effective catalytic oxidative degradation of micropollutants including tetracycline hydrochloride (TCH), methylene blue, and methyl blue. Moreover, the carboxyl groups on the MOF formed covalent bonds (–COO–) with the hydroxyl groups in MnO₂ between layers, which increased the interaction between MnO₂ nanosheets to form stable interlayer channels. Specifically, the optimal composite membrane achieved a high removal rate of TCH micropollutant (93.4%), high water treatment capacity (282 L·m^–2·h^–1·MPa^–1), and excellent long-term stability (1200 min). This study provides a simple and easily scalable strategy to construct fast, efficient, and stable 2D catalytic mass-transfer channels for the efficient treatment of micropollutants in wastewater.