PI/SiO2@ZIF-8 nanofiber membrane with excellent high temperature exhaust gas filtration performance and efficiently formaldehyde adsorption capacity

Nowadays, modern industries are rapidly developing, which is caused by a significant amount of high-temperature exhaust gases in the atmosphere, and it contains complex pollutants, formaldehyde, solid particles, and harmful gases that are discharged. For this scenario, the conventional filtering materials are challenged for prevention of high-temperature exhaust gas formaldehyde volatilization because they are composed of metal and inorganic materials caused by oxidation-prone and resilient wear. A recently introduced technique to fabricate composite nanofiber membranes with high strength, modulus, efficiency, low resistance for high-temperature exhaust gas filtering, and its capability to adsorb formaldehyde was discussed in this study. Initially, Polyamide acid (PAA) solution and silicon dioxide (SiO₂) nanomicrospheres are used as raw materials for producing electrostatic and thermal imidization Polyimide (PI/SiO₂) nanofiber membranes (NFMs) in co-spinning processes. Furthermore, zeoliticimidazolate framework-8 (ZIF-8) was transferred into PI/SiO₂ NFMs and produced the PI/SiO2@ZIF-8 NFM. These findings show that adding SiO₂ nanomicrospheres reduced the fiber packing density as well as air filtration resistance, and PI/SiO2@ZIF-8 NFMs achieve up to 99.703% filtration efficiency and maintain a pressure drop of 178.7 Pa. The weight loss rate is only 4% at temperatures above 300 °C, and the heat resistance is outstanding. Moreover, the PI/SiO2@ZIF-8 NFMs demonstrate a good formaldehyde adsorption performance with a saturation adsorption capacity for formaldehyde within 4 h of 41.58 mg/g, which is more than 12 times that of the PI/SiO2 NFMs without ZIF-8.