Multifunctional ZIF-67@SiO2 Membrane for High Efficiency Removal of Particulate Matter and Toxic Gases

A multifunctional air filtration membrane is urgently required for high efficiency removal of particulate matter (PM) and capture of airborne toxic gases (SO2, NOx, VOCs, etc.). Zeolite imidazole frameworks (ZIFs), as a subclass of metal–organic frameworks (MOFs), hold promise for poisonous pollutant capture due to their excellent adsorption performance and high thermal and chemical stability. Here, a facile strategy is demonstrated to synthesize a multifunctional air filtration membrane through in situ growth of ZIF-67 nanoparticles on a flexible silica nanofiber membrane (ZIF-67@SiO2 NFM), which significantly improved the contact area of the membrane with SO2 and PM. When it underwent a standard PM removal test, the prepared ZIF-67@SiO2 NFM showed the highest PM2.5 removal efficiency of 100% at a relatively low pressure drop of 335 Pa with the impregnation time being 24 h. At the same time, due to the load of ZIF-67, the SO2 adsorption capacity up to 1013 mg/g could be realized in the obtained membrane when exposed to a SO2/N2 mixed flow with a humidity of 55%. Furthermore, during the incense smoke experiment, the PM2.5 filtering efficiency of the prepared ZIF-67@SiO2 membrane could reach 98.9% under an initial concentration of 1000 μg·m–3. This work proposes a simple and practical strategy to not only prepare a high-performance multifunctional nanofiber membrane but also achieve the capture of SO2 and PM with high efficiency.