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Characterization of Particle Chemistry: Size Distribution and Dynamics in Various Processes

This project explores the characterization of particle chemistry, analyzing qualitative size distributions and their dynamics. It examines how size distributions can change over time through processes where volume is conserved (like coagulation) or not (such as condensation and evaporation). We focus on the chemical composition of particles, including homogeneous and heterogeneous mixtures. Examples highlight pharmaceutical powders for inhalation and emissions from incinerators. A survey of analytical techniques (AAS, ICP-AES, TOF-MS, etc.) illustrates how to measure chemical composition effectively.

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Characterization of Particle Chemistry: Size Distribution and Dynamics in Various Processes

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Presentation Transcript

  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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