Understanding ion-mobility and transport properties of aerosol nanowires

Kim, S.H.; Mulholland, George W.; Zachariah, Michael R.

doi:10.1016/j.jaerosci.2007.06.003

Cited by 42 publications

(64 citation statements)

References 17 publications

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“…0.5 ), Consequently, we may say that that the Heywood diameter D prj is roughly equal to the mobility equivalent diameter, as was reported by Kim et al (2007). In the following filtration experiments, we used DMAclassified MWCNT particles with mobility equivalent diameters of 100, 200, and 300 nm as nominal size.…”

Section: Preparation Of Test Fibrous Aerosolmentioning

confidence: 58%

“…In Table 1, we also see the difference between the mobility diameter, D m , and the projected area equivalent diameter, D prj . Kim et al (2007) The mobility diameters calculated from the average diameter and length of MWCNT by this equation are shown in the first column from the right of Table 1. The calculated mobility diameters (244, 272, and 344 nm) are larger than those of nominal mobility diameters (100, 200, and 300 nm) due to the fraction of multiply charged particles with larger size.…”

Section: Preparation Of Test Fibrous Aerosolmentioning

confidence: 99%

“…More recently, regarding carbon nanotubes and nanowires, Kim et al (2007) generated MWCNT aerosol particles of controlled diameter and length by laser ablation together with an aerosol classification technique. They investigated the Brownian rotation and electrostatic alignments of MWCNT aerosol in a differential mobility analyzer (DMA) and provided clear relationship between the mobility and the geometric size of MWCNT.…”

Section: Introductionmentioning

confidence: 99%

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Filtration of Multi-Walled Carbon Nanotube Aerosol by Fibrous Filters

Seto¹,

Furukawa²,

Ōtani³

et al. 2010

Aerosol Science and Technology

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Filtration efficiency of multi-walled carbon nanotube (MWCNT) aerosol by fibrous filter was evaluated experimentally. Mono-mobility test aerosols with electrical mobility diameter of 100, 200, and 300 nm were generated by the atomization of MWCNT aqueous suspension followed by mobility classification with a differential mobility analyzer (DMA). By analyzing the shape of classified aerosol particles under a scanning electron microscope, it was found that the DMA-classified 300 nm particles were fibrous in shape and had uniform diameter of about 60 nm and length of 2.1 micrometer. On the other hand, 100 nm and 200 nm particles contained a fairly large amount of multiply charged fibrous particles with a larger diameter. These test aerosols were challenged to a medium performance fibrous filter at various filtration velocities. As a result, fibrous particles were captured by fibrous filter at a higher collection efficiency than the spherical particles with the same mobility. By analyzing the single fiber capturing efficiency, interception incorporating the rotation of fibrous particles is found to be the dominant capturing mechanism for the fibrous particles in the studied size range.

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Section: Preparation Of Test Fibrous Aerosolmentioning

confidence: 58%

Section: Preparation Of Test Fibrous Aerosolmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Filtration of Multi-Walled Carbon Nanotube Aerosol by Fibrous Filters

Seto¹,

Furukawa²,

Ōtani³

et al. 2010

Aerosol Science and Technology

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show abstract

“…Once it occurred, the monodisperse MWCNTs classified by DMA would not have a correct mobility size as desired. Shorter nanowires (<»450 nm) with an aspect-ratio of <»30 and wire diameter of 15 nm could randomly rotate in the electric field of DMA when the sheath flow rate was 10 L min ¡1 (Kim et al 2007, Li et al 2012b). This finding was in agreement with our previous work (Wang et al 2011b).…”

Section: ¡1mentioning

confidence: 99%

Carbon Nanotube Penetration Through Fiberglass and Electret Respirator Filter and Nuclepore Filter Media: Experiments and Models

Chen

Wang

Bahk

et al. 2014

Aerosol Science and Technology

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Three different respirator filter media (two electrets and one fiberglass) were challenged with monodisperse multi-walled carbon nanotubes (MWCNTs) of mobility diameters 20-500 nm at 5.3 and 10.6 cm s ¡1 face velocities. The penetration data were compared with that of sphere-like NaCl particles. The MWCNT penetrations were generally lower than those of NaCl at both face velocities in all three filters. However, the MWCNTs had a slightly higher penetration than the NaCl in the fiberglass filter at 10.6 cm s ¡1 face velocity when their mobility diameters were lower than 50 nm and the alignment effect was expected to occur. Results from the scanning electron microscopic (SEM) analysis supported the hypothesis of the alignment effect, which showed that the MWCNTs tend to be straighter or with higher aspectratios at the mobility sizes less than 100 nm, leading them more readily to align with the flow. Therefore, caution should be exercised when respirators are used against the MWCNTs with the mobility diameters less than 100 nm. The single fiber theory predicted the penetration of both particles in the fiberglass filters well for the particles with below 100 nm mobility diameters but discrepancies occurred beyond 100 nm. The theory still predicted the NaCl penetration through the electret filters well for the sizes below 100 nm but only predicted the MWCNT penetration well for »20-30 nm. The Nuclepore filter and the corresponding capillary tube model were adopted to study the mechanical deposition mechanisms of MWCNTs. The model was found to predict MWCNT penetration very well when the effective length of the MWCNT was taken into account.

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“…In this context, for spherical particles because of their isotropic nature, the electric field (low or high) does not influence the mobility inside the DMA. However, non-spherical particles may orient differently especially at high electric fields thus producing a electric field dependent mobility which can then be used to extract the shape information of the particle [226]. As mentioned earlier, it is beyond the scope of this dissertation to discuss such non-spherical particles.…”

Section: A1 Introductionmentioning

confidence: 99%

Electrospray–differential mobility analysis of bionanoparticles

Guha

Tarlov

et al. 2012

Trends in Biotechnology

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The growth of the multibillion dollar bionanoparticle industry has spurred the development of new physical characterization methods. One such method, electrospraydifferential mobility analysis (ES-DMA) constitutes an electrospray for aerosolization of bionanoparticles (such as viruses, gold-nanoparticles, proteins, nanoparticle-protein complexes) and an ion mobility method that operates at atmospheric conditions, and separates bionanoparticles spatially. This dissertation identifies some relevant "problem" areas for ES-DMA by reviewing selected applications.Some such problems are: proteins while passing through ES capillaries are found to interact with it and thus produce time dependent size distributions. Further, it is thought that adsorbed proteins may subsequently desorb and influence size distributions with the ES-DMA which may concomitantly affect quantification of aggregates. These artifacts are studied systematically and it is demonstrated that ES-DMA can quantify adsorption-desorption of complex protein mixtures at high shear rates. Further, it is shown that desorbing proteins do not have a significant effect on size distributions. Another artifact of the ES takes place during the aersolization process. Two units (called monomers) of a bionanoparticle may get encapsulated in the same ES droplet and upon drying of the droplet create artificial dimers thus affecting quantification with ES-DMA. Assuming Poisson distribution, this thesis provides a systematic approach that can be undertaken to eliminate this artifact. A third artifact arises from the low sensitivity of the DMA to size increase. When a ligand (for e.g. protein) adsorbs to a bionanoparticle it creates an increase in the size of the later, which can be used to quantify the amount of ligand adsorbed per bionanoparticle. As ligands can change conformations upon adsorption, using ES-DMA for such applications may be flawed. This issue has been identified and a solution has been provided by integrating a mass analyzer after the ES-DMA.After correcting for these artifacts, this dissertation delves into characterization of different types of bionanoparticles and demonstrates that ES-DMA has several advantages over other traditional techniques such as transmission electron microscopy, size exclusion chromatography, analytical ultracentrifugation, dynamic light scattering and plaque assay and thus has immense potential to become a process analytical technique in biomanufacturing environments. ELECTROSPRAY-DIFFERENTIAL MOBILITY ANALYSIS OF BIONANOPARTICLES

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Understanding ion-mobility and transport properties of aerosol nanowires

Cited by 42 publications

References 17 publications

Filtration of Multi-Walled Carbon Nanotube Aerosol by Fibrous Filters

Filtration of Multi-Walled Carbon Nanotube Aerosol by Fibrous Filters

Carbon Nanotube Penetration Through Fiberglass and Electret Respirator Filter and Nuclepore Filter Media: Experiments and Models

Electrospray–differential mobility analysis of bionanoparticles

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