MnO2-loaded flexible mullite nanofiber filter materials for removing particulate matter and formaldehyde from indoor air

•Mullite nanofibers loaded MnO2 nanoparticles were prepared by a facilitate method.•MNF@MnO2 membranes can effectively decompose HCHO at room temperature.•MNF@MnO2 membranes exhibit ultra-high filtration efficiency for PM2.5. Among indoor air pollutants, particulate matter with a diameter less than 2.5 μm (PM2.5) and volatile organic compounds with small molecules are the greatest threat to human health. However, complete removal of these pollutants is challenging, and the incomplete removal causes secondary pollution. In this study, manganese dioxide nanoparticles (MnO2 NPs) were controllably grown on the surface of mullite nanofibers (MNFs) using a potassium permanganate (KMnO4) reduction method to prepare MNF@MnO2 composite membranes that could effectively remove PM2.5 and formaldehyde from indoor air. After loading the optimal amount of MnO2 NPs, the filtration efficiency of a nanofiber membrane for salt particles with diameters of 0.3 μm increased from 97.32 % to 99.47 %, and the removal rate of formaldehyde reached 88.3 % within 170 min in the closed laboratory space. After five repeated tests, the formaldehyde decomposition rate remained above 80 %. The MNF@MnO2 membrane was successfully used to prepare an indoor air purifier filter element, demonstrating considerable potential for improving the indoor air quality and reducing health risks.