Efficient removal of high-temperature particulate matters via a heat resistant and flame retardant thermally-oxidized PAN/PVP/SnO₂ nanofiber membrane

Particulate matters (PMs) emissions from energy consumption contribute the vast majority of PM pollution, which are typically associated with high temperatures (>300 °C) and are difficult to remove directly at high temperatures. Electrospinning nanofiber membranes have irreplaceable advantages of high removal efficiency and low pressure drop for PMs filtration, however, the efficient filtration of PMs at high temperature is challenging for polymer-based nanofiber membranes because of the poor heat resistance and inflammability. Herein, we design a thermally-oxidized polyacrylonitrile/polyvinylpyrrolidone/SnO₂ (OPAN/PVP/SnO₂) nanofiber membrane by performing the thermally induced cyclization and oxidation reaction of PAN/PVP/SnCl₂ nanofiber membrane at 350 °C in air. During the thermal oxidization process, Sn²⁺ acted as a catalyst and activation, preventing the melting and fusion of PAN nanofibers. The addition of PVP greatly increased the mechanical properties of OPAN/SnO₂ nanofiber membrane. The prepared OPAN/PVP/SnO₂ nanofiber membrane possesses superior PMs filtration performance at room temperature, with the PM_0.3 and PM_2.5 filtration efficiency of 99.53% and 99.98%, respectively. The OPAN/PVP/SnO₂ nanofiber membrane exhibits high temperature tolerance up to 350 °C and wide pH tolerance of 1–14, it remains a high PMs removal efficiency of 98.51% at 350 °C and 98.67% at 300 °C. Moreover, the OPAN/PVP/SnO₂ nanofiber membrane shows excellent fire retarding and self-extinguishing property not shown in pristine PAN nanofiber membrane. This work provides a novel approach for clean use of energy via a cost-effective, heat-resistant, and flame-retardant nanofiber membrane.