An Efficient Strategy to Boost the Removal Efficiency for Submicron Particles and VOCs of Polypropylene in the Complex Flue Gas

Particulate matter (PM) is recognized as a significant environmental risk factor, with profound adverse effects on human health. The development of air filters that maintain high performance under complex environmental conditions remains a challenge. Herein, a novel composite air filter was fabricated by the in situ growth of ZIF-8 nanoparticles onto polypropylene (PP) fibers in this study, aiming to enhance filtration efficiency and adaptability in challenging environments. The results demonstrated that the PP/ZIF-8 membrane contained a substantial number of rhombic dodecahedron crystals. The removal efficiencies could be obtained at 84.6%, 92.6%, 93.5%, 95.8%, and 96.9% for PM_0.5, PM_1.0, PM_2.5, PM_5.0, and PM₁₀, respectively. The pressure drop decreased from 0.19 to 0.07 kPa. The filtration efficiency of PM_0.5 for PP/ZIF-8 remained as high as 80% after 50 filtration cycles. VOCs containing nitrogen and carbon elements were removed preferentially for PP/ZIF-8, while oxygen-containing compounds may be competitively suppressed from complex flue gas. The adsorption capacity of PP/ZIF-8 for benzene VOCs was higher than that of PP, and the actual adsorption process for benzene could be better described by the pseudo-first-order kinetic model. Additionally, the concentrations of fulvic acid substances and high-molecular-weight humic substances were significantly decreased in the exhaust gas. Electrostatic interaction and chemisorption contributed significantly to PM and VOCs removal. This study proposes a novel strategy to boost the removal efficiency and adaptability of the air filter in complex environmental conditions with low pressure drop.