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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. Starter size distribution: . Processes in which volume is conserved. Coagulation, communition or breakup, restructuring .

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More on Characterization

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  1. More on Characterization • Qualitative size distribution dynamics • Particle chemistry • Particle chemical characterization

  2. Size distributions may change over time Starter size distribution:

  3. Processes in which volume is conserved Coagulation, communition or breakup, restructuring

  4. Processes in which volume not conserved Condensation, evaporation, nucleation, sedimentation,

  5. In class project – changing shapes of distributions

  6. 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

  7. 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

  8. 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

  9. 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)

  10. Analytical situations: in class problem

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