Project

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System for comprehensive optical, chemical and structural characterization of flame-made carbonaceous nanoparticles

English title System for comprehensive optical, chemical and structural characteriza-tion of flame-made carbonaceous nanoparticles
Applicant Pratsinis Sotiris E.
Number 183298
Funding scheme R'EQUIP
Research institution Institut für Verfahrenstechnik ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Mechanical Engineering
Start/End 01.12.2018 - 30.11.2019
Approved amount 216'730.00
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All Disciplines (9)

Discipline
Mechanical Engineering
Particle Physics
Chemical Engineering
Physical Chemistry
Organic Chemistry
Other disciplines of Engineering Sciences
Fluid Dynamics
Climatology. Atmospherical Chemistry, Aeronomy
Material Sciences

Keywords (8)

Gas Phase Chemistry; Particulate Emissions; Global Warming; Carbonaceous Nanoparticles; Radiative Forcing; Flame Aerosol Reactors; Nucleation; Multi Scale Modeling

Lay Summary (German)

Lead
System für die umfassende optische, chemische und strukturelle Charakterisierung von flammen-basierten kohlenstoffhaltigen Nanopartikeln
Lay summary

Das Ziel dieses Projekts ist es, ein einzigartiges System zur Sammlung von flammensynthetisierten  kohlenstoffhaltigen Nanopartikeln zur umfassenden Charakterisierung ihrer optischen, chemischen und morphologischen Eigenschaften zu schaffen. Diese Teilchen sind allgegenwärtig und erregen dadurch  Aufmerksamkeit in verschiedenen Bereichen der Wissenschaft. Ihre Bildung durch Verbrennung ist für die Synthese funktioneller Nanomaterialien von entscheidender Bedeutung, hat aber auch einen großen Einfluss auf Gesundheit und Umwelt. Zum Beispiel ist Ruß nach Wert und Volumen das größte flammgefertigte nanostrukturierte Material (eine $ 13 Mrd. Industrie weltweit), während Ruß, ein dem Industrieruß ("carbon black") sehr ähnliches Material, ein Luftschadstoff ist. Häufig werden bei der Charakterisierung solcher Partikel jedoch die sich verändernden optischen Eigenschaften, Zusammensetzung und fraktalartigen Struktur vernachlässigt. Dies führt zu erheblichen Fehlern, z. B. bei der Abschätzung des direkten Strahlungsantrieb von Ruß für die globale Erwärmung sowie der Russoxidationsrate und der Massenkonzentration. Dies sind entscheidende Parameter für die Entwicklung und gegebenenfalls Auferlegung von Umweltvorschriften, für das Prozessdesign für die Nanopartikel-Synthese, für die Optimierung von Abgasnachbehandlungssystemen, für die verantwortungsbewusste Modellierung des Klimawandels sowie für die zuverlässige Kalibrierung von optischen Brandmeldern.
              Diese Forschung soll eine wissenschaftliche Basis bilden für  unser Verständnis der optischen Eigenschaften, der Morphologie und der Masse kohlenstoffhaltiger Nanopartikel.. Auf diese Weise wird ein glaubwürdiges Vorgehen entwickelt zur Abschätzung ihrer Auswirkungen auf Umwelt und Gesundheit.. Die Notwendigkeit des vorgeschlagenen Systems ist auf zwei Gründe zurückzuführen: 1. In der Literatur verfügbare Daten basieren oft auf unrealistischen  Vereinfachungen, was zu widersprüchlichen Partikeleigenschaften führte. Zum Beispiel wird angenommen, dass die optischen Eigenschaften des Rußes trotz signifikanter Änderungen in der Russstruktur und der chemischen Zusammensetzung während seiner Bildung in Flammen und Alterung in der Atmosphäre konstant sind. 2. Partikeleigenschaften werden oft aus kohlenstoffhaltigen Grosspartikeln und nicht aus Nanopartikeln erhalten. Zum Beispiel wird angenommen, dass die Russoxidationsraten trotz ihrer unterschiedlichen Zusammensetzung und Größenunterschiede mit denen der Kohle identisch sind!

Direct link to Lay Summary Last update: 06.12.2018

Lay Summary (English)

Lead
System for comprehensive optical, chemical and structural characterization of flame-made carbonaceous nanoparticles
Lay summary

The aim of this project is to create a unique set of systems for collection of flame-made carbonaceous nanoparticles for comprehensive characterization of their optical, chemical and morphological properties. These particles are ubiquitous in attracting attention in various fields of science. Their formation by combustion is critical in synthesis of functional nanomaterials but also has high impact on health and environment. Carbon black, for example, is the largest flame-made nanostructured material by value and volume (a $13B industry worldwide), while soot - a material very similar to carbon black - is an air pollutant. Often characterization of such particles is performed neglecting their evolving optical properties, composition and fractal-like structure. This leads to significant errors, as for example, in estimating the direct radiative forcing of soot for global warming as well as the soot oxidation rate and mass concentration. These are critical parameters for developing and eventually imposing environmental regulations, process design for nanoparticle synthesis, optimizing exhaust after-treatment systems, responsible modeling of climate change and reliable calibration of optical fire detectors.

              This research will place our understanding of the optical properties, morphology and mass of carbonaceous nanoparticles on a firm scientific basis. That way a credible scheme for obtaining their environmental and health impact will be developed. The need for the proposed system is caused by two reasons: 1. Available data in the literature were obtained and post-processed with unrealistic oversimplifications resulting in contradicting particle properties.  For example, optical properties of soot are assumed to be constant despite significant changes in soot structure and chemical composition during its formation in flames and aging in the atmosphere. 2. Particle properties are often obtained from bulk carbonaceous particles and not nanoparticles. For example, soot oxidation rates are assumed to be identical to those of coal despite their different composition and orders of magnitude difference in size!

Direct link to Lay Summary Last update: 06.12.2018

Responsible applicant and co-applicants

Publications

Publication
Estimating the internal and surface oxidation of soot agglomerates
Kelesidis Georgios A., Pratsinis Sotiris E. (2019), Estimating the internal and surface oxidation of soot agglomerates, in Combustion and Flame, 209, 493-499.
Light scattering from nanoparticle agglomerates
Kelesidis Georgios A., Kholghy Mohammad Reza, Zuercher Joel, Robertz Julian, Allemann Martin, Duric Aleksandar, Pratsinis Sotiris E. (2019), Light scattering from nanoparticle agglomerates, in Powder Technology.

Abstract

The aim of this request is to acquire a unique set of systems for collection and comprehensive characterization of optical, electrical, chemical and morphological properties of flame made carbonaceous nanoparticles evolving from their inception to oxidation. Carbonaceous nanoparticles are ubiquitous in attracting attention in various fields of science and their formation by combustion is critical in synthesis of functional nanomaterials but also has high impact on health and environment. Carbon black for example, is the largest flame-made nanomaterial by value and volume (a $10B industry), while soot - a material very similar to carbon black - is an air pollutant. Particle characterization is often performed neglecting their evolving refractive index, composition, fractal-like structure and polydispersity. This leadins to significant errors, for example, in estimating direct radiative forcing of soot for global warming, oxidation rate or particle mass. These are critical parameters for imposing environmental regulations, process design for nanoparticle synthesis, optimizing exhaust after treatment systems, modeling climate change and reliable calibration of optical fire detectors. Our laboratory focuses on synthesis and characterization of properties of flame-made nanoparticles. We also develop multiscale models to explain the complex and highly coupled phenomena during nanoparticle formation in flames connecting synthesis conditions to particle properties from first principles. Using multiscale models benchmarked with experiments performed in flame-relevant conditions, there is an opportunity to accurately obtain critical particle properties that cannot be calculated from measurements alone. For example, the evolving soot refractive index can be described based on soot aggregate mass, fractal like structure and composition to accurately estimate soot radiative forcing and its effects on global warming. Also, soot oxidation rate can be accurately calculated using scaling laws obtained from simulations by post-processing oxidation data accounting for the fractal-like structure of soot particles. To progress our research towards obtaining all required critical particle parameters, new measurements are needed to accurately and coherently characterize properties of particles produced and processed in flame relevant conditions. The need for the proposed system is caused by three reasons: 1. Available data in the literature are very scattered, were collected over decades and often obtained and post-processed with unrealistic oversimplifications resulting in contradicting particle properties. For example, refractive index of soot is assumed to be a constant value despite significant changes in soot structure and chemical composition during its formation in flames and aging in the atmosphere! 2. Particle properties are often obtained from bulk carbonaceous particles and not nanoparticles. For example, soot oxidation rates are assumed to be identical to those of coal despite orders of magnitude difference in their size and different composition! and 3. Average properties are obtained for polydisperse population of particles that hinders the ability to benchmark simulations performed for single particles (monodisperse) by comparing to the measured properties for an ensemble of polydisperse particles. The proposed system together with the core strength of our group in synthesis, characterization and multiscale process modeling of flame-made nanoparticles enables us to perform comprehensive and coherent measurements applied in projects for the characterization of particle (A) morphology, (B) chemical composition and (C) optical and electrical properties as they evolve from inception to oxidation. The measurements will be performed to go beyond currently investigated conditions to cases for very small particles (d_m < 10 nm) and oxidation at high temperatures (T >1600 K), where currently limited data are available.
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