Measurement of Nanoparticle Agglomerates by Combined Measurement of Electrical Mobility and Unipolar Charging Properties

Wang, Jing; Shin, Weon Gyu; Mertler, Michael; Sachweh, Bernd; Fißan, H.; Pui, David Y.H.

doi:10.1080/02786820903401427

Cited by 53 publications

(50 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For a loose agglomerate with equally sized primary particles the capacity change depends on the primary particle size. Making use of this dependency, Wang et al (2010) developed a semi-empirical model, which allows the on-line primary particle size determination for chain like agglomerates with low fractal dimensions from the measured values of charge per agglomerate. The developed model has been adjusted by making use of measured charge per particle data of spherical and loosely agglomerated silver particles.…”

Section: Existing Technologies and Data Evaluation Proceduresmentioning

confidence: 99%

“…Due to unavoidable coagulation and unwanted or wanted sintering processes they often occur in form of loose agglomerates consisting out of primary particles touching each other in one point or sintered aggregates with stronger chemical bonds. In this paper we will not only consider loose agglomerates as has been done in the past (Lall and Friedlander, 2006a;Lall et al, 2006b;Wang et al, 2010), but we will consider data evaluation procedures for the structurally more complicated aggregates. Although the primary particles in agglomerates can have different shapes (spheres, fibers, plates) depending on the material and the synthesis process, very often they are spherical with diameters of a few nanometer to below 100 nm.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rationale for Data Evaluation of the Size Distribution Measurements of Agglomerates and Aggregates in Gases with Extended SMPS-Technology

Fißan

Kaminski

Asbach

et al. 2013

Aerosol Air Qual. Res.

View full text Add to dashboard Cite

Engineered nanoparticles (ENP) very often occur in form of agglomerates built up from spherical primary particles and sintered aggregates. The properties of materials making use of ENPs depend on the distributions of the structural properties of agglomerated/aggregated ENPs. The amount and structural properties of accidentally released ENPs are also of interest with regard to their transport and environmental effects.We report on the possibilities of using extended SMPS-technology with the addition of an Aerosol Particle Mass Analyzer (APM) and/or an Electrical Sensor (ES), as well as the results of recently developed sintering models, to describe the structures of agglomerates and aggregates. Proposals are made for suitable data evaluation procedures to yield accurate property distributions.

show abstract

Section: Existing Technologies and Data Evaluation Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rationale for Data Evaluation of the Size Distribution Measurements of Agglomerates and Aggregates in Gases with Extended SMPS-Technology

Fißan

Kaminski

Asbach

et al. 2013

Aerosol Air Qual. Res.

View full text Add to dashboard Cite

show abstract

“…Further experimental confirmation of this theory using artificially generated carbon particles is given by Lall et al 121 UNPA. The UNPA utilizes a DMA, CPC, and nanoparticle surface area monitor (NSAM) that includes a unipolar charger combined with an electrometer to characterize nanoparticle morphology and measure the number, surface area, and volume distributions of loose nanoparticle aggregates, 111 including DPM. The UNPA response to a size-selected particle is given as a sensitivity that is defined as the current measured by the NSAM divided by the number concentration measured by the CPC.…”

Section: Effective Density Comparisonsmentioning

confidence: 99%

Alternatives to the Gravimetric Method for Quantification of Diesel Particulate Matter near the Lower Level of Detection

Swanson

Kittelson

Pui

et al. 2010

Journal of the Air & Waste Management Association

View full text Add to dashboard Cite

This paper is part of the Journal of the Air & Waste Management Association's 2010 special issue on combustion aerosol measurements. The issue is a combination of papers that synthesize and evaluate ideas and perspectives that were presented by experts at a series of workshops sponsored by the Coordinating Research Council that aimed to evaluate the current and future status of diesel particulate matter (DPM) measurement. Measurement of DPM is a complex issue with many stakeholders, including air quality management and enforcement agencies, engine manufacturers, health experts, and climatologists. Adoption of the U.S. Environmental Protection Agency 2007 heavy-duty engine DPM standards posed a unique challenge to engine manufacturers. The new standards reduced DPM emissions to the point that improvements to the gravimetric method were required to increase the accuracy and the sensitivity of the measurement. Despite these improvements, the method still has shortcomings. The objectives of this paper are to review the physical and chemical properties of DPM that make gravimetric measurement difficult at very low concentrations and to review alternative metrics and methods that are potentially more accurate, sensitive, and specific. Particle volatility, size, surface area, and number metrics are considered, as well as methods to quantify them. Although the authors believe that an alternative method is required to meet the needs of engine manufacturers, the methods reviewed in the paper are applicable to other areas where the gravimetric method detection limit is approached and greater accuracy and sensitivity are required. The paper concludes by suggesting a method to measure active surface area, combined with a method to separate semi-volatile and solid fractions to further increase the specificity of the measurement, has potential for reducing the lower detection limit of DPM and enabling engine manufacturers to reduce DPM emissions in the future.

show abstract

“…If polydisperse NP agglomerates are used as challenging aerosols in filtration experiments, the data evaluation for the measurement could be based on sphere assumptions or open-structured agglomerate assumptions, for example, using a model developed by . This model was validated and justified for openstructured silver agglomerates in the studies reported before Wang et al 2010). We have examined the filtration data using silver NP agglomerates.…”

Section: Introductionmentioning

confidence: 99%

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

2013

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

Measurement of Nanoparticle Agglomerates by Combined Measurement of Electrical Mobility and Unipolar Charging Properties

Cited by 53 publications

References 43 publications

Rationale for Data Evaluation of the Size Distribution Measurements of Agglomerates and Aggregates in Gases with Extended SMPS-Technology

Rationale for Data Evaluation of the Size Distribution Measurements of Agglomerates and Aggregates in Gases with Extended SMPS-Technology

Alternatives to the Gravimetric Method for Quantification of Diesel Particulate Matter near the Lower Level of Detection

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

Contact Info

Product

Resources

About