A system to assess the stability of airborne nanoparticle agglomerates under aerodynamic shear

Ding, Yaobo; Riediker, Michael

doi:10.1016/j.jaerosci.2015.06.001

Cited by 16 publications

(19 citation statements)

References 33 publications

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“…The use of relatively small amounts of test materials makes the method potentially valuable as an alternative tool for testing powder dustiness. The ranking of levels of airborne particles generated by our system for some common materials was similar to those observed in existing aerosolization systems 19 , such as the rotating drum 15,17 , continuous drop 23 , and vortex shaker methods 24 . Furthermore, the adjustable energy input (air flow rate) can also be used for studying the stability of nanoparticle powder agglomerates.…”

Section: Representative Resultssupporting

confidence: 71%

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A System to Create Stable Nanoparticle Aerosols from Nanopowders

Ding

Riediker

2016

JoVE

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Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring minimal amounts of test materials (min. 200 mg), for studying powder aerosolization behavior and aerosol properties. The aerosolization procedure follows the concept of the fluidized-bed process, but occurs in the modified volume of a V-shaped aerosol generator. The airborne particle number concentration is adjustable by controlling the air flow rate. The system supplied stable aerosol generation rates and particle size distributions over long periods (0.5-2 hr and possibly longer), which are important, for example, to study aerosol behavior, but also for toxicological studies. Strict adherence to the operating procedures during the aerosolization experiments ensures the generation of reproducible test results. The critical steps in the standard protocol are the preparation of the material and setup, and the aerosolization operations themselves. The system can be used for experiments requiring stable aerosol concentrations and may also be an alternative method for testing dustiness. The controlled aerosolization made possible with this setup occurs using energy inputs (may be characterized by aerosolization air velocity) that are within the ranges commonly found in occupational environments where nanomaterial powders are handled. This setup and its operating protocol are thus helpful for human exposure and risk assessment.

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Section: Representative Resultssupporting

confidence: 71%

“…Steady aerosolization can be maintained for sufficiently long durations for robust aerosol characterizations. The system's performance has been described in detail in two previous publications 19,20 .…”

Section: Introductionmentioning

confidence: 99%

A System to Create Stable Nanoparticle Aerosols from Nanopowders

Ding

Riediker

2016

JoVE

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“…A system based on fluidization was developed for continuous aerosolization of dry powders in small quantities ( Figure 1a; Ding and Riediker 2015). Aerosolization is achieved inside a pressureresistant glass funnel.…”

Section: System I-fluidization Funnelmentioning

confidence: 99%

“…These tests provide qualitative results, but not quantitative ones, on how different forces trigger deagglomeration. Critical orifices have been used in these processes as means of applying high levels of shear forces (Stahlmecke et al 2009;Sosnowski et al 2014;Ding and Riediker 2015).…”

Section: Introductionmentioning

confidence: 99%

Dustiness and Deagglomeration Testing: Interlaboratory Comparison of Systems for Nanoparticle Powders

Ding

Stahlmecke

Jiménez

et al. 2015

Aerosol Science and Technology

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Different types of aerosolization and deagglomeration testing systems exist for studying the properties of nanomaterial powders and their aerosols. However, results are dependent on the specific methods used. In order to have well-characterized aerosols, we require a better understanding of how system parameters and testing conditions influence the properties of the aerosols generated. In the present study, four experimental setups delivering different aerosolization energies were used to test the resultant aerosols of two distinct nanomaterials (hydrophobic and hydrophilic TiO 2 ). The reproducibility of results within each system was good. However, the number concentrations and size distributions of the aerosols created varied across the four systems; for number concentrations, e.g., from 10 3 to 10 6 #/cm 3 . Moreover, distinct differences were also observed between the two materials with different surface coatings. The article discusses how system characteristics and other pertinent conditions modify the test results. We propose using air velocity as a suitable proxy for estimating energy input levels in aerosolization systems. The information derived from this work will be especially useful for establishing standard operating procedures for testing nanopowders, as well as for estimating their release rates under different energy input conditions, which is relevant for occupational exposure.

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“…A dustiness test is not intended to comminute the powder and generate new particles. This precludes the use of high shear critical orifices [24] and high impact processes [25] for dustiness determination.…”

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics analysis of the Venturi Dustiness Tester

2017

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Dustiness quantifies the propensity of a finely divided solid to be aerosolized by a prescribed mechanical stimulus. Dustiness is relevant wherever powders are mixed, transferred or handled, and is important in the control of hazardous exposures and the prevention of dust explosions and product loss. Limited quantities of active pharmaceutical powders available for testing led to the development (at University of North Carolina) of a Venturi-driven dustiness tester. The powder is turbulently injected at high speed (Re ~ 2 × 104) into a glass chamber; the aerosol is then gently sampled (Re ~ 2 × 103) through two filters located at the top of the chamber; the dustiness index is the ratio of sampled to injected mass of powder. Injection is activated by suction at an Extraction Port at the top of the chamber; loss of powder during injection compromises the sampled dustiness. The present work analyzes the flow inside the Venturi Dustiness Tester, using an Unsteady Reynolds-Averaged Navier-Stokes formulation with the k-ω Shear Stress Transport turbulence model. The simulation considers single-phase flow, valid for small particles (Stokes number Stk <1). Results show that ~ 24% of fluid-tracers escape the tester before the Sampling Phase begins. Dispersion of the powder during the Injection Phase results in a uniform aerosol inside the tester, even for inhomogeneous injections, satisfying a necessary condition for the accurate evaluation of dustiness. Simulations are also performed under the conditions of reduced Extraction-Port flow; results confirm the importance of high Extraction-Port flow rate (standard operation) for uniform distribution of fluid tracers. Simulations are also performed under the conditions of delayed powder injection; results show that a uniform aerosol is still achieved provided 0.5 s elapses between powder injection and sampling.

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A system to assess the stability of airborne nanoparticle agglomerates under aerodynamic shear

Cited by 16 publications

References 33 publications

A System to Create Stable Nanoparticle Aerosols from Nanopowders

A System to Create Stable Nanoparticle Aerosols from Nanopowders

Dustiness and Deagglomeration Testing: Interlaboratory Comparison of Systems for Nanoparticle Powders

Computational fluid dynamics analysis of the Venturi Dustiness Tester

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