Nanoparticle aggregate volume determination by electrical mobility analysis: Test of idealized aggregate theory using aerosol particle mass analyzer measurements

Lall, Anshuman A.; Rong, Weizhi; Mädler, Lutz; Friedlander, Sheldon K.

doi:10.1016/j.jaerosci.2007.12.010

Cited by 31 publications

(38 citation statements)

References 34 publications

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“…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.…”

Section: Effective Density Comparisonsmentioning

confidence: 67%

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

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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.

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Section: Effective Density Comparisonsmentioning

confidence: 67%

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

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“…In several cases of different synthesis methods it has been observed that loose agglomerates with similar low fractal dimension have been formed. Lall et al (2008) produced similar loose iron oxide and carbon agglomerates using laser ablation. They were used to verify successfully their model for loose agglomerates.…”

Section: Existing Technologies and Data Evaluation Proceduresmentioning

confidence: 96%

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.

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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.

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“…This spread in the particle diameter leads to a larger spread in particle mass. Thus the trend in particle concentration measured as a function of APM voltage is wider than the APM transfer function even though the particles can be considered as "mono-disperse" in size (Lall, et al 2008).…”

Section: Introductionmentioning

confidence: 98%

“…An aerosol particle mass analyzer (APM) has recently been used in a number of studies for direct measurement of particle mass (Lall et al 2008;McMurry et al 2002;Park et al 2004;Zhou et al 2008). The APM classifies particles by balancing the electrostatic and centrifugal forces (Ehara et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Online Nanoparticle Mass Measurement by Combined Aerosol Particle Mass Analyzer and Differential Mobility Analyzer: Comparison of Theory and Measurements

Lall

Guha

et al. 2009

Aerosol Science and Technology

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A combination of a differential mobility analyzer (DMA) and aerosol particle mass analyzer (APM) is used to measure the mass of NIST Standard Reference Materials (SRM R ) PSL spheres with 60 and 100 nm nominal diameter, and NIST traceable 300 nm PSL spheres. The calibration PSL spheres were previously characterized by modal diameter and spread in particle size. We used the DMA to separate the particles with modal diameter in a narrow mobility diameter range. The mass of the separated particles is measured using the APM. The measured mass is converted to diameter using a specific density of 1.05. We found that there was good agreement between our measurements and calibration modal diameter. The measured average modal diameters are 59.23 and 101.2 nm for nominal diameters of 60 and 100 nm (calibration modal diameter: 60.39 and 100.7 nm) PSL spheres, respectively. The repeatability uncertainty of these measurements is reported. For 300 nm, the measured diameter was 305.5 nm, which is an agreement with calibration diameter within 1.8%.The effect of spread in particle size on the APM transfer function is investigated. Two sources of the spread in "mono-dispersed" particle size distributions are discussed: (a) spread due to the triangular DMA transfer function, and (b) spread in the calibration particle size. The APM response function is calculated numerically with parabolic flow through the APM and diffusion broadening. As expected from theory, the calculated APM response function and measured data followed a similar trend with respect to APM voltage. However, the theoretical APM transfer function is narrower than the measured APM response.

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Nanoparticle aggregate volume determination by electrical mobility analysis: Test of idealized aggregate theory using aerosol particle mass analyzer measurements

Cited by 31 publications

References 34 publications

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

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

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

Online Nanoparticle Mass Measurement by Combined Aerosol Particle Mass Analyzer and Differential Mobility Analyzer: Comparison of Theory and Measurements

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