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More on Characterization. Qualitative size distribution dynamics Particle chemistry Particle chemical characterization. Size distributions may change over time. Starter size distribution: . Processes in which volume is conserved. Coagulation, communition or breakup, restructuring .

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more on characterization
More on Characterization
  • Qualitative size distribution dynamics
  • Particle chemistry
  • Particle chemical characterization
size distributions may change over time
Size distributions may change over time

Starter size distribution:

slide3

Processes in which volume is conserved

Coagulation, communition or breakup, restructuring

slide4

Processes in which volume not conserved

Condensation, evaporation, nucleation, sedimentation,

slide6

Chemical composition not always same

  • Varying degrees of chemical homogenaity in particle mixtures
  • Particles all of one chemical species (ie salt granules) – chemically homogeneous
  • Particles are all of one chemical species, but the particles are mixed – externally mixed
  • Particles are of two or more chemical components, but composition of each particle is same – internally mixed
  • Individual particles have different compositions
slide7

Chemical composition may vary with size

Pharmaceutical powders for inhalation - want small drug particles mixed with and loosely bound to larger inert particles

Emissions from incinerators – some high volatility compounds evaporate in high temperature zone and nucleate downstream forming ultrafine high surface area particles

More examples

slide8

How to measure chemical composition?

Many techniques – survey of analytical chemistry

Some need large sample of material, so need to take average over whole size distribution, and/or time

Some need extremely small amounts of material so representative sampling is crucial

Some can tell you composition on-line or nearly on-line

Some require off-line analysis

slide9

SADK – secret acronym decoder kit

  • Atomic absorption spectroscopy (AAS)
  • Inductively coupled plasma- atomic emission spectroscopy (ICP-AES)
  • Laser induced breakdown spectrometry (LIBS)
  • Time of Flight Mass spectrometry of aerosols (TOF-MS)
  • X-ray Fluorescence (XRF)
  • Proton Induced X-Ray Emission (PIXE)
  • Neutron activation analysis (NAA)
  • X-ray photoelectron spectroscopy (XPS)
  • Auger spectroscopy
  • X-ray diffraction (XRD)
  • Energy dispersive X-ray spectroscopy (EDX or EDS)
  • Electron energy loss spectrometry (EELS)
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