Physical characterization of engineered aerosol particles

Research output: ThesisDoctoral Thesis (compilation)

Abstract

This thesis will explore parts of the life of engineered nanoparticles, from generation in research environments and
process monitoring, to emissions in an industrial setting. The aim is to give insights into how the particles can be
characterized in different settings and how different characterization methods can be applied depending on need or
demand.
Airborne nanoparticles have been around forever but the use of them in specialized materials has increased
dramatically during the past decades. The new materials bring improvements to old applications, and brand new uses
as the world of nanotechnology expands. It is, however, not only one-sided positive effects from this increase in use;
some of these materials have properties previously experienced as health hazards. The physical size and amounts of
material handled during the production can be different from what has been experienced before and with that, new
hazards might arise. In order to assess these hazards, careful characterization of the particle behavior can be utilized in
controlled environments to further the knowledge on how the particles might behave out in the real world during use and
application. Particles can be characterized in many different ways and aspects. Finding out which path that suits a
certain situation is a key to make a successful measurement campaign or experiment. The systems used to produce
these particles also need to be well characterized. In addition to safe handling, well characterized generation systems
will also allow for new uses and exploration of materials previously not investigated.
In this thesis, I have characterized the initial stages of particles generated with spark discharge discovering how the
particles evolve depending on process parameters milliseconds after generation. I further dive deeper into the spark
discharge characterization and show how the emitted light from the discharge can be correlated with the particles being
produced and show how the input power doesn’t linearly correlate with particles produced in this process. In the same
system, I successfully generate particles of InSb. It is demonstrated how a reducing atmosphere during generation is
critical for the formation of pure particles of this material. Several different characterization techniques to determine the
properties of the generated particles are described.
One of the most interesting properties of nanoparticles from a toxicological view point is surface area. Knowing the
surface area of complex particles is, however, not always straightforward and is often difficult to measure directly. I
present an overview of a set of models that can be used to estimate the surface area of agglomerated particles
generated from different particle sources. The input to the methods relies on online measurements of mobility diameter,
mass, and offline characterization of morphology via microscopy samples.
No matter how harmful particles with specific properties are to humans, there is no harm unless people get exposed to
the particles. I present results from an extensive workplace campaign in which we utilized online aerosol instruments to
characterize the emissions. A new method for classifying carbon nanotube materials via electron microscopy from filter
samples, as well as from surface sampling with adhesive tape, is further introduced.
From this campaign release of engineered nanoparticles at several occasions during the work day was found. It was
evident that online methods alone would not enable us to discern carbon nanotubes from other particles but with the
combination of online time resolved characterization of emissions and extensive microscopy analysis emission events
were identified. It was also revealed that the surface contamination of engineered particles were extensive. Several
sampled surfaces showed contamination by not only carbon nanotubes but also of nanomaterial which were not
handled during the time of the measurements.
From this thesis it is clear that measuring nanoparticles is as difficult as you make it. It is possible to measure with
simple means to yield results that are sufficient to give an indication that some things needs to improve. In this thesis I
will also show that an extensive arsenal of equipment can yield results which complement and build upon each other.
While it is possible to measure all kinds of data on the same aerosol given enough time and resources, it is clear that
the optimization and tailoring of a study might be the real challenge.

Details

Authors
  • Linus Ludvigsson
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Sciences
  • Other Materials Engineering
  • Nano Technology

Keywords

Translated title of the contributionPhysical characterization of engineered aerosol particles
Original languageSwedish
QualificationDoctor
Awarding Institution
Supervisors/Assistant supervisor
Award date2017 Sep 22
Place of PublicationLund
Edition1:a
Publisher
  • Solid State Physics
Print ISBNs978-91-7753-407-5
Electronic ISBNs978-91-7753-408-2
Publication statusPublished - 2017 Aug 29
Publication categoryResearch

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