Electrospun membrane has been used commercially as a high efficiency air filters for trapping fine airborne particles. As nanofibers with high surface area, this property also makes it attractive for removing harmful gas. This may be achieved by neutralization or adsorption.
There are several ways which electrospun fibers may be used to neutralize toxic gas. Ramaseshan (2011) used electrospinning to produce ZnTiO3 nanofibers from its precursor. The annealed fibers have diameters mainly in the range of 50 to 300 nm. ZnTiO3 containing α-Zn2TiO4 demonstrate the best efficiency with Paraoxon, simulant for the organophosphorus compounds, decomposition of 91% in the first 50 minutes and CEES (2-chloroethyl ethyl sulfide), simulant for mustard gas, decomposition of 69% in the first 10 minutes. Instead of using pure inorganic fibers which can be brittle, another method is to incorporate active agents into polymeric fibers. Ramaseshan (2011) fabricated (3-carboxy-4- iodosobenzyl) oxy-β-Cyclodextrin from o-iodosobenzoic acid(IBA) and β-cyclodextrin (β-CD) for incorporation into polyvinyl chloride nanofibers. With a mass of (3-carboxy-4- iodosobenzyl) oxy-β-Cyclodextrin to PVC ratio of 0.5:1, the rate of hydrolysis of the nanofibrous membrane was found to be 11.5 times faster than that of activated carbon. Chen (2009) used a blend of reactive polyacrylamidoxime (PAAO) and polyacrylonitrile (PAN) as the carrier to form electrospun fibers. The reactive fibers were shown to hydrolyse of p-nitrophenyl acetate (PNPA) which mimics nerve agents. However, the study also showed that the presence of the PAN matrix also affects the accessibility of the reactive sites.
Electrospun fibers may also be used for adsorption of other compounds such as volatile organic compounds (VOC). Ge et al (2016) used loess powder (LP) for incorporation into electrospun polyurethane fibers. Loess is used in purification of water for adsorption of heavy metals and organic compounds. Their research found that 30% wt LP nanoparticles loading into the nanofibers showed the highest VOC absorption capacity with a 300% improvement over pure polyurethane fibers. LP loading lower and higher than this amount results in reduced VOC absorption. At higher loading, the reduction in absorption was due to agglomeration of the nanoparticles which reduces its effective surface area. The composite film showed VOC absorption trend of toluene > benzene > chloroform.
Kim et al used commercially available fly ash (by-product of coal-fired electric power stations) for incorporation into polyurethane (PU) electrospun fibers. Their experiment showed that 30% loading of fly ash gives the highest absorption capacity compared to other concentration. The composite fibers were able to give an absorption of about 45 µg/g fiber for xylene and styrene, about 22 µg/g fiber for chloroform and between 30 and 40 µg/g fiber for toluene and benzene.
A source of industrial air pollution comes from burning fossil fuels which releases sulfur dioxide (SO2) into the environment. Therefore, it is necessary to remove SO2 from the flue gas before it is being discharged to the atmosphere. Xin et al (2020) constructed electrospun polyvinylidene fluoride (PVDF) fibers loaded with SiO2 particles of size 20 - 30 nm for removal of SO2. SiO2 particles were added to PVDF solution for electrospinning into functionalized fibers. Up to 60 wt% SiO2 particles were added to the fiber and the surface of the fibers were rough as compared to much smoother surface morphology of pure PVDF fibers. Signs of SiO2 particles can already be seen on the surface of PVDF fibers with loading of 10 wt% SiO2. A 20 wt% loading of SiO2 was found to be optimal demonstrating absorption fluxes and SO2 removal efficiencies up to 1.03 × 10-3 mol m-2 s-1 and 49.1%, respectively.
Gas pollutants may be oxidized to less harmful with the aid of catalytic fibers. Platinum and palladium are commonly used in catalytic converters and there are several studies on the fabrication of electrospun fibers containing Pt or Pd nanoparticles. Shahreen et al (2013, 2015) fabricated titania nanofibers loaded with palladium nanoparticles by electrospinning a solution of titanium isopropoxide and PVP loaded with PdCl2 salt. As a salt, PdCl2 aids in the formation of beads-free nanofibers by increasing the conductivity of the solution [Shahreen et al 2015]. Titania fiber containing PdO was formed by sintering and the PdO was reduced to Pd nanoparticles using hydrazine reaction. The resultant composite fibers showed significant conversion of NO and CO gases to NO2 and CO2 respectively
Published date: 30 January 2018
Last updated: 07 September 2021
▼ Reference
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Chen L. Next Generation of Electrospun Textiles for Chemical and Biological Protection and Air Filtration. PhD Thesis 2009 Massachusetts Institute of Technology.
Open Access
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Ge J C, Kim J H, Choi N J. Electrospun Polyurethane/Loess Powder Hybrids and Their Absorption of Volatile Organic Compounds. Advances in Materials Science and Engineering 2016; 2016: 8521259.
Open Access
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Kim H J, Pant H R, Choi N J, Kim C S. Composite electrospun fly ash/polyurethane fibers for absorption of volatile organic compounds from air. Chemical Engineering Journal 2013; 230: 244.
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Ramaseshan R. Decontamination of chemical warfare simulants using electrospun media. PhD Thesis 2011. National University of Singapore.
Open Access
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Shahreen L, Chase G G, Turinske A J, Nelson S A, Stojilovic N. NO decomposition by CO over Pd catalyst supported on TiO2 nanofibers. Chemical Engineering Journal 2013; 225: 340.
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Shahreen L, Chase G G. Effects of Electrospinning Solution Properties on Formation of Beads in TiO2 Fibers with PdO Particles. Journal of Engineered Fibers and Fabrics 2015; 10: 136.
Open Access
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Xin Q, Xie K, Liang Q, Xu Li, Zeng Y, Zhao Y, Zhang L, Wang S, Li H, Zhang Y. Electrospinning in membrane contactor: Manufacturing Elec-PVDF/SiO2 superhydrophobic surface for efficient flue gas desulphurization applications. Green Chemical Engineering 2020 Article in press
Open Access
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