Electreted Polyetherimide-silica Nanofibrous Membranes Forair Filtration

With the rapid development of china’s industrialization, more and more dust particulate are bedischarged into the atmosphere, the PM2.5(the size of particulate less than2.5μm) is not causeserious harm on human health, but also has a tremendous impact on the harmony of the naturalenvironment. Therefore, we design and prepare an effective method to solve the dust pollution inthe air and filter it from the source material, which was a major issue for healthy livelihood.Conventional polypropylene (PP) melt-blown materials which is full of electric charge after beingcharged have good filtration efficiency. However, the charge stability of PP melt-blown electretmaterials is greatly affected by the environment condition, the attenuation speed of the electriccharge is very fast, so the filtration efficiency decrease rapidly. Electret technology needs additionalprocessing steps and high-cost, the article proposed the idea of doping electret particles to polymersolution to produce high filtration efficiency, low pressure drop and high charge stabilitynanofibrous membrane by electrospinning to improve the defect.Firstly, polyetherimide (PEI) dissolved in DMF/NMP=1/1(wt/wt)(N, N-dimethylfomaimide(DMF) and N-methyl-2-pyrrolidone (NMP)) was electrospun byadjusting the processing parameterof different concentrations of PEI nanofibrous membranes. Thinking about the the morphology offiber, the filtration performance and the mechanical properties of PEI nanofibrous membranes, wechoose the optimum concentration (20%) for detailed investigation.20wt%of PEI solutionscontaining6wt%of Boehmite, silicon dioxide (SiO2), silicon nitride (Si3N4), barium titanate(BaTiO3) were electrospun to produce electrospinning-electrets hybrid nanofibrous. The nanobrousshows high filtration performance than PEI nanofibrous because of plenty of space charge. The bestelectret is SiO2. Finally, we check the concentrations of SiO2to the effect of morphology, porous structure,filtration performance and surface wettability. Experimental results have shown that when thecontent of the SiO2added to6wt%, the filtration efficiency of PEI-SiO2fibrous membrane ismaximum, about95.20%and the pressure drop is11.7Pa ((under face velocity of32L/min).Anymore The hierarchical structured PEI-SiO2membranes were endowed with promisingsuperhydrophobicity with a water contact angle of152°, allowing their better self-cleaningperformance compared with commercial polypropylene (PP) filter media.In addition, the influence of basic weight and air flow on the PEI/SiO2hybrid fibrousmembrane filtration performance is also studied. The filtration efficiency increase with the increasein basic weight, The filtration efficiency decrease with the increase in air flow. Furthermore, unlikethe commercial PP-based filtration media, the as-prepared membranes can be treated at200℃for30min without sacrificing filtration efficiency (99.99%) and pressure drop (61Pa) owing to thecombined contribution of polarization and space charges. We anticipate that this promisingelectreted fibrous medium will act as a core part of numerous air filtration systems, including ultra-low penetration air filters, clean room, respirator, and protective clothing.