Generation and investigation of airborne silver nanoparticles with specific size and morphology by homogeneous nucleation, coagulation and sintering

Ku, Bon Ki; Maynard, Andrew

doi:10.1016/j.jaerosci.2005.05.003

Cited by 65 publications

(45 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, silver particles can be generated in nearly spherical shape (Ku and Maynard, 2006) and they are physically stable and inert with respect to chemical reactions.…”

Section: Determination Of Copas Detection and Counting Characteristicsmentioning

confidence: 99%

Experimental characterization of the COndensation PArticle counting System for high altitude aircraft-borne application

et al. 2009

View full text Add to dashboard Cite

Abstract.A characterization of the ultra-fine aerosol particle counter COPAS (COndensation PArticle counting System) for operation on board the Russian high altitude research aircraft M-55 Geophysika is presented. The COPAS instrument consists of an aerosol inlet and two dual-channel continuous flow Condensation Particle Counters (CPCs) operated with the chlorofluorocarbon FC-43. It operates at pressures between 400 and 50 hPa for aerosol detection in the particle diameter (d p ) range from 6 nm up to 1 µm. The aerosol inlet, designed for the M-55, is characterized with respect to aspiration, transmission, and transport losses. The experimental characterization of counting efficiencies of three CPCs yields d p50 (50% detection particle diameter) of 6 nm, 11 nm, and 15 nm at temperature differences ( T ) between saturator and condenser of 17 • C, 30 • C, and 33 • C, respectively. Non-volatile particles are quantified with a fourth CPC, with d p50 =11 nm. It includes an aerosol heating line (250 • C) to evaporate H 2 SO 4 -H 2 O particles of 11 nm

show abstract

“…Furthermore, silver particles can be generated in nearly spherical shape (Ku and Maynard, 2006) and they are physically stable and inert with respect to chemical reactions.…”

Section: Determination Of Copas Detection and Counting Characteristicsmentioning

confidence: 99%

Experimental characterization of the COndensation PArticle counting System for high altitude aircraft-borne application

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Thus, the sintered spheres are not totally coalesced, instead smaller particles are attached to the surface due to the heterogeneous coagulation. A number of previous studies (Schmidt-Ott 1988; Ku and Maynard 2006;Kim et al 2009a;Cena et al 2012) confirmed using SEM or low resolution TEM that the Ag particles sintered at 600°C had shapes close to spheres. Our TEM analysis also showed the overall particle shape was close to a sphere, but the detailed structure of the small particles at the surface is for the first time reported.…”

Section: Resultsmentioning

confidence: 78%

“…Nitrogen gas was used as the carrier gas with a flow rate of 1.5 lpm. The general methodology that was employed is similar to the ones reported before (Ku and Maynard 2006;Shin et al 2009a, b). Silver NP, collided and attached to each other in the agglomeration chamber leading to NP agglomerates made up of a few up to hundreds primary particles.…”

Section: Materials Methods and Characterizationmentioning

confidence: 99%

“…Silver agglomerates, among the others, are a health concern; they are expected to be more toxic than spherical silver particles with the same mass due to larger surface area. The additional reason for choosing silver agglomerates for this study is the extensive number of reports on their generation and properties and the advantage of easy control over the morphology by adjusting the sintering temperature (Ku and Maynard 2006;Shin et al 2009a, b).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Filtration behavior of silver nanoparticle agglomerates and effects of the agglomerate model in data analysis

Buha

Fißan

Wang

2013

Nanotechnology for Sustainable Development

View full text Add to dashboard Cite

In many data evaluation procedures for particle measuring devices and in filtration models, spherical particles are assumed. However, significant fractions of aerosol particles are agglomerates of small primary spheres. The morphology of particles in filtration processes may not be known a priori and if the filtration data are processed with wrong assumption, errors can be induced. In this work, we have quantified such errors for the case of open-structured agglomerates. Filtration efficiency tests with polydisperse silver nanoparticle agglomerates and their sintered spheres were performed. After the sintering process, particles with a compact structure with the shape close to a sphere are obtained, which are referred to as sintered spheres in the present study. The testing method involved generation of particulate forms, passing the particles through the testing section, and measurement of the particle number concentrations and size distributions before and after the filter. Measurements of the aerosols upstream and downstream of the filter were conducted using scanning mobility particle sizers (SMPS, TSI Inc.), which covered the rage from 10 to 480 nm. Particles were additionally characterized from the electron microscopic images and the average primary particle size was determined to be 16.8 nm. The number-size distribution curves were obtained and used for penetration calculation. The penetration was dependent on the particle size and morphology. Silversintered spheres were captured with a lower efficiency than agglomerates with the same mobility diameter because of the stronger interception effect for agglomerates. Data analysis of the number-size distribution for agglomerates was processed based on sphere assumption and using the model for openstructured agglomerates developed by Lall and Friedlander. The efficiencies based on total concentrations of number, surface and volume were affected when the agglomerate model was used. The effect was weakest for the total number efficiency and strongest for the total volume efficiency. Filtration efficiency curves for agglomerates were additionally plotted as a function of the volume equivalent diameter or number of primary particles per agglomerate, because the latter parameters provide more information for the agglomerate structure.

show abstract

“…Soot agglomerates are a type of nonspherical particles that are often found in the ambient aerosol (Katrinak et al, 1993). TiO 2 and Ag particles in industrial applications also have agglomerate morphologies (Pratsinis, 1998;Ku and Maynard, 2006). The physical and chemical characterization of nonspherical and fractal particles is an important area of current aerosol research (Friedlander and Pui, 2004).…”

Section: Introductionmentioning

confidence: 99%

Estimates of Non-Ideal Effects on the Friction Coefficient of Agglomerates

Shin

Mulholland

Kim

et al. 2011

Aerosol Air Qual. Res.

View full text Add to dashboard Cite

There are several characteristics of silver agglomerates that are not incorporated in existing models for agglomerate dynamics. These characteristics include particle alignment in the electric field, necking between particles, polydispersity of the primary particles, and variable primary sphere size. Estimates of these features on the agglomerate dynamics were computed as perturbations to the Chan-Dahneke agglomerate model. The variable primary sphere size effect results in the largest change from the idealized model with about a 10% increase in scaling exponents for both friction coefficientnumber of primary particles (η) and mass-mobility diameter (D fm ). The second largest change is a 4% decrease in the exponent η and a 4% increase in the exponent (D fm ) from the alignment in the electric field. The effects of necking between particles and polydispersity of the primary particles are negligible for the two exponents. The combined effect, excluding the variable primary particle size, results in a 17.5% decrease in the dynamic shape factor for agglomerates with a 300 nm mobility diameter. Adjusting the model by this amount provides a significant improvement in the agreement between the model and silver agglomerate measurements for the dynamic shape factor. Experimentally the number of primary spheres is determined from the mass of the agglomerate assuming a constant primary sphere diameter. The predicted apparent exponent η based on a 10% variability in the primary sphere size is about a 5% less than the apparent exponent assuming a constant primary sphere size. This is a significant effect relative to the observed 15% decrease in η (Shin et al., 2009a) as the agglomerate size increases from the free molecular regime into the transition regime.

show abstract

Generation and investigation of airborne silver nanoparticles with specific size and morphology by homogeneous nucleation, coagulation and sintering

Cited by 65 publications

References 47 publications

Experimental characterization of the COndensation PArticle counting System for high altitude aircraft-borne application

Experimental characterization of the COndensation PArticle counting System for high altitude aircraft-borne application

Filtration behavior of silver nanoparticle agglomerates and effects of the agglomerate model in data analysis

Estimates of Non-Ideal Effects on the Friction Coefficient of Agglomerates

Contact Info

Product

Resources

About