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Physical characterization of engineered aerosol particles

Ludvigsson, Linus LU (2017)
Abstract (Swedish)
Den här avhandlingen handlar om luftburna designade nanopartiklar och hur man
tar reda på vilka egenskaper de har. Luftburna partiklar eller aerosoler är något som
människan alltid har haft omkring sig. Oavsett om det varit i form av pollen, rök från
eldstaden, eller från astmainhalatorn så har de alltid varit där och påverkat oss. I varje
andetag drar vi in flera tusen partiklar, men vilken typ de är beror på var någonstans
man är. I många fall är partiklarna inte något som gynnar kroppen men just eftersom
inandning av partiklar inte är något nytt har flera olika system i kroppen utvecklats för
att ta hand om de partiklar som fastnar i lungorna, andra partikeltyper är svårare för
kroppen att hantera. Ett... (More)
Den här avhandlingen handlar om luftburna designade nanopartiklar och hur man
tar reda på vilka egenskaper de har. Luftburna partiklar eller aerosoler är något som
människan alltid har haft omkring sig. Oavsett om det varit i form av pollen, rök från
eldstaden, eller från astmainhalatorn så har de alltid varit där och påverkat oss. I varje
andetag drar vi in flera tusen partiklar, men vilken typ de är beror på var någonstans
man är. I många fall är partiklarna inte något som gynnar kroppen men just eftersom
inandning av partiklar inte är något nytt har flera olika system i kroppen utvecklats för
att ta hand om de partiklar som fastnar i lungorna, andra partikeltyper är svårare för
kroppen att hantera. Ett historiskt exempel är asbestfibrer som när de används till
isolering har många goda egenskaper, men som när de blir luftburna och andas in
orsakar cancer. Genom att studera hur asbestfibrer påverkar kroppen och varför de är
farliga kom man fram till att det till stor del berodde på att de var olösliga i lungorna.
Med den vetskapen designade man nya material som inte hade de oönskade effekterna
som asbestfibrer. Kolnanorör är en ny typ av material som nu börjat användas med till
synes liknande egenskaper som asbestfibrer men där användningsområdena skiljer sig.
För att undvika liknande problem som uppstod för asbest vidtar man idag betydligt
grundligare undersökningar, speciellt vid tillverkningen för att minimera riskerna att
någon kommer till skada.
För att kunna avgöra vilka som är skadliga och vilka som vi kan dra nytta av
behöver vi veta vad som gör en partikel god eller ond. Till detta behövs tekniker från
många olika fält som inte naturligt varit en del av samma område inom
naturvetenskapen eller tekniken. När det dessutom handlar om nya material som
används inom nya områden är behovet av nya grepp för att förstå dessa partiklar
uppenbart.
I detta arbete visar jag på flera olika angreppsvinklar som kan användas för att få en
helhetsbild av luftburna nanopartiklar. Partiklarna som studerats har haft sitt ursprung
både i faktiska tillämpningar ute på arbetsplatser och medvetet genererade i labbet. Jag
har undersökt vad som sker från själva tillblivelsen av partiklar i gnisturladdningar, till
fundamentala egenskaper som hur de växer till under de första ögonblicken efter sitt
skapande, samt när och var partiklar släpps ut under industriell produktion. Genom att
förstå hela processen kan man enklare designa partiklar med de egenskaper man vill
ha, och undvika de man inte vill ha. En god kontroll över vad man producerar hjälper
xiv
också till när man ska ta reda på vad som faktiskt spelar roll när man studerar vilka
effekter partiklarna har på, till exempel, levande celler.
Beroende på i vilket sammanhang partiklarna förekommer och anledningen till att
man vill undersöka dem måste man göra en avvägning i hur pass noggrann man kan
vara. Det hade varit bäst om man kunde undersöka allt men oftast är det inte fallet.
Omfattande undersökningar kräver resurser både i form av tid och pengar, och dessa
är ofta begränsade. I fallet med arbetsmiljö är det oftare av intresse att, i alla fall till en
början, kunna peka på om det finns en uppenbar fara för de som vistas i miljön än att
ge detaljerad information som skulle ta längre tid att få fram. Ibland kan förvånansvärt
enkla metoder ge goda och relevanta resultat. För grundforskning i en kontrollerad
miljö ges möjligheten att kunna studera betydligt mindre delar av en process så som
partikelbildning. De upptäckter man gör i det steget kan senare användas för till
exempel diagnostik av processen under produktion eller för optimering av egenskaper
hos partiklarna.
Jag har i mina studier tagit fram metoder för att identifiera och klassificera
nanomaterial som släpps ut under produktion genom att använda analysmetoder som
tidigare inte använts i fältet. Jag har genom mina studier kunnat kartlägga
partikelbildning från de allra första ögonblicken till processade nanopartiklar under
partikelbildning och genom detta möjliggjort optimering av gnisturladdningsgenerering
av nanopartiklar. Jag har också lyckats producera nanopartiklar av material
som tidigare aldrig gjorts. (Less)
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... (More)
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. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Mädler, Lutz, University of Bremen, Germany
organization
alternative title
Physical characterization of engineered aerosol particles
publishing date
type
Thesis
publication status
published
subject
keywords
Fysicumarkivet A:2017:Ludvigsson
edition
1:a
pages
189 pages
publisher
Solid State Physics
defense location
Lecture hall Rydbergsalen, Fysicum, Sölvegatan 14, Lund University, Faculty of Engineering.
defense date
2017-09-22 09:15
ISBN
978-91-7753-407-5
978-91-7753-408-2
language
Swedish
LU publication?
yes
id
eed111c6-dc80-488c-be5e-667165bc01b7
date added to LUP
2017-08-28 13:31:57
date last changed
2018-04-16 13:41:38
@phdthesis{eed111c6-dc80-488c-be5e-667165bc01b7,
  abstract     = {This thesis will explore parts of the life of engineered nanoparticles, from generation in research environments and<br/>process monitoring, to emissions in an industrial setting. The aim is to give insights into how the particles can be<br/>characterized in different settings and how different characterization methods can be applied depending on need or<br/>demand.<br/>Airborne nanoparticles have been around forever but the use of them in specialized materials has increased<br/>dramatically during the past decades. The new materials bring improvements to old applications, and brand new uses<br/>as the world of nanotechnology expands. It is, however, not only one-sided positive effects from this increase in use;<br/>some of these materials have properties previously experienced as health hazards. The physical size and amounts of<br/>material handled during the production can be different from what has been experienced before and with that, new<br/>hazards might arise. In order to assess these hazards, careful characterization of the particle behavior can be utilized in<br/>controlled environments to further the knowledge on how the particles might behave out in the real world during use and<br/>application. Particles can be characterized in many different ways and aspects. Finding out which path that suits a<br/>certain situation is a key to make a successful measurement campaign or experiment. The systems used to produce<br/>these particles also need to be well characterized. In addition to safe handling, well characterized generation systems<br/>will also allow for new uses and exploration of materials previously not investigated.<br/>In this thesis, I have characterized the initial stages of particles generated with spark discharge discovering how the<br/>particles evolve depending on process parameters milliseconds after generation. I further dive deeper into the spark<br/>discharge characterization and show how the emitted light from the discharge can be correlated with the particles being<br/>produced and show how the input power doesn’t linearly correlate with particles produced in this process. In the same<br/>system, I successfully generate particles of InSb. It is demonstrated how a reducing atmosphere during generation is<br/>critical for the formation of pure particles of this material. Several different characterization techniques to determine the<br/>properties of the generated particles are described.<br/>One of the most interesting properties of nanoparticles from a toxicological view point is surface area. Knowing the<br/>surface area of complex particles is, however, not always straightforward and is often difficult to measure directly. I<br/>present an overview of a set of models that can be used to estimate the surface area of agglomerated particles<br/>generated from different particle sources. The input to the methods relies on online measurements of mobility diameter,<br/>mass, and offline characterization of morphology via microscopy samples.<br/>No matter how harmful particles with specific properties are to humans, there is no harm unless people get exposed to<br/>the particles. I present results from an extensive workplace campaign in which we utilized online aerosol instruments to<br/>characterize the emissions. A new method for classifying carbon nanotube materials via electron microscopy from filter<br/>samples, as well as from surface sampling with adhesive tape, is further introduced.<br/>From this campaign release of engineered nanoparticles at several occasions during the work day was found. It was<br/>evident that online methods alone would not enable us to discern carbon nanotubes from other particles but with the<br/>combination of online time resolved characterization of emissions and extensive microscopy analysis emission events<br/>were identified. It was also revealed that the surface contamination of engineered particles were extensive. Several<br/>sampled surfaces showed contamination by not only carbon nanotubes but also of nanomaterial which were not<br/>handled during the time of the measurements.<br/>From this thesis it is clear that measuring nanoparticles is as difficult as you make it. It is possible to measure with<br/>simple means to yield results that are sufficient to give an indication that some things needs to improve. In this thesis I<br/>will also show that an extensive arsenal of equipment can yield results which complement and build upon each other.<br/>While it is possible to measure all kinds of data on the same aerosol given enough time and resources, it is clear that<br/>the optimization and tailoring of a study might be the real challenge.},
  author       = {Ludvigsson, Linus},
  isbn         = {978-91-7753-407-5},
  keyword      = {Fysicumarkivet A:2017:Ludvigsson},
  language     = {swe},
  month        = {08},
  pages        = {189},
  publisher    = {Solid State Physics},
  school       = {Lund University},
  title        = {Physical characterization of engineered aerosol particles},
  year         = {2017},
}