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Introduction

Introduction. Chemical Properties & Physical Properties Chemical compositions Total number concentration, optical coefficients, density, refractive index, equilibrium water content On-line & Off-line Measurement Analysis on line: monitor Analysis in Lab

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Introduction

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  1. Introduction • Chemical Properties & Physical Properties • Chemical compositions • Total number concentration, optical coefficients, density, refractive index, equilibrium water content • On-line & Off-line Measurement • Analysis on line: monitor • Analysis in Lab • Integral Measurement & Size-Resolved Measurement

  2. Introduction Physical Properties P. H. McMurry, Atmospheric Environment 34 (2000) 1959-1999

  3. Introduction Chemical Properties P. H. McMurry, Atmospheric Environment 34 (2000) 1959-1999

  4. Measurements of Aerosol Physical Properties Integral measurements • Number Concentration • CNC, CPC • Particle Mass Concentration • Manual Methods: Filter and Balance • Total Suspended Particulate (TSP) Sampler • Automated Method: • Beta gauges (PM10) • TEOM (Tapered Element Oscillating Microbalance)

  5. Measurements of Aerosol Chemical/Physical Properties Integral Measurements Total Suspended Particulate (TSP) High Volume (Hi-Vol) Sampler Principle: Inertial Impaction, Interception Volumetric flow: 60-100 m3/hr Filter size: 20 x 25 cm filter 24 hours sampling

  6. Measurements of Aerosol Physical Properties Integral Measurements Beta gauges Principle: A beta gauge consists of two basic components – a source of radiation, and a radiation detector. The filter to be measured is placed between the source and detector. Beta Gauge Particulate Monitor determines particulate concentration by measuring the amount of radiation a sample absorbs when exposed to a radioactive source. In general, the more energy absorbed, the greater the particulate concentration.

  7. Measurements of Aerosol Physical Properties Integral Measurements TEOM (Tapered Element Oscillating Microbalance ) It measures the mass collected on an exchangeable filter cartridge by monitoring the corresponding frequency changes of a tapered element. The sample flow passes through the filter, where particulate matter collects, and then continues through the hollow tapered element on its way to an electronic flow control system and vacuum pump. As more mass collects on the exchangeable filter, the tube's natural frequency of oscillation decreases. A direct relationship exists between the tube's change in frequency and mass on the filter.

  8. Measurements of Aerosol Chemical PropertiesOff-line measurements • Filter sampling Filtration • TSP (HiVol) sampler, PM10 (HiVol) sampler • Dichot sampler (PM2.5 and PM2.5~10) • Cyclone (PM1, PM2.5 and PM10) • Personal sampler (ex. ORBO 53 tube) Inertial Impaction • UW III Cascade impactor • MOUDI (Multi-Orifice Uniform Deposit Impactor) Gravimetric Settling - Dry Deposition • Electron microscopy • Morphology and Element Composition

  9. Filter sampling Example: Inlet, Filter holder, Flow measurement device , Pump

  10. Measurements of Aerosol Chemical/Physical Properties Integral Measurements PM10 (Hi-Vol) sampler Size: PM10 Use: Mass concentration, Chemical composition Principle: Inertial Impaction, Interception Volumetric flow: 60-100 m3/hr Filter size: 20 x 25 cm filter 24 hours sampling

  11. Measurements of Aerosol Chemical/Physical Properties Size Resolved Measurements Virtual Dichotomous sampler Size: PM2.5 and PM2.5-10 Use: Mass concentration, Chemical composition

  12. Measurements of Aerosol Chemical/Physical Properties Size Resolved Measurements Cyclone Small Particle would be collected by filter Large Particle would be removed

  13. Measurements of Aerosol Chemical/Physical Properties Size Resolved Measurements MOUDI (Multi-Orifice Uniform Deposit Impactor)

  14. Measurements of Aerosol Chemical/Physical Properties Integral Measurements Dry deposition sampler Principle: Gravimetric Settling

  15. Measurements of Aerosol Chemical Properties Integral Measurements Measurements of Aerosol Chemical PropertiesReal-time measurements • Real-time particulate carbon analyzers • The instrument's operating cycle consists of two phases: collection and analysis. Thermal-CO2 Method Collection PhaseThe Series 5400 Monitor draws a sample stream of ambient air through a size selective inlet and directs it onto an impactor mounted inside a collector Analysis Phase 350 0C: Organic carbon 750 0C: Element Carbon

  16. Filter Media • Several characteristics are important in selecting filter media • Particle Sampling Efficiency • Mechanical Stability • Chemical Stability • Temperature Stability • Blank Concentrations • Flow Resistance and Loading Capacity • Cost and Availability

  17. Teflon membrane 25, 37 ,47 mm Physical characteristics High particle collection efficiencies Pore size: 1, 2, 3, 5, 10 mm Melts at 60 oC High flow resistance Chemical characteristics Inert to adsorption of gases Low hydroscopicity Low blank weight Compatible Analysis Methods Gravimetry, PIXE, INAA, AAS, ICP, IC, AC Commonly used filter media for particulate sampling and analysis Cost: 

  18. Commonly used filter media for particulate sampling and analysis Cost:  • Pure Quartz-Fiber • Chemical characteristics • Conatins large and variable quantities of Al and Si • Passively adsorbs organic vapors. Absorbs little HNO3, NO2, and SO2 • Low hydroscopicity • Compatible Analysis Methods • ICP/AES, ICP/MS, IC, AC, T, TOR, TOM, TOT, OA • 25, 37, 47 mm, 20.3 X 25.4 cm • Physical characteristics • High Particle Collection Efficiencies • Soft and friable edges flake in most fiber holders • Melts at > 900 oC • Moderate flow resistance

  19. Commonly used filter media for particulate sampling and analysis Cost:  • Glass Fiber • Chemical characteristics • High blank weight • Absorbs HNO3, NO2, SO2, and organic vapors • Low hydroscopicity • Compatible Analysis Methods • Gravimetry, OA, XRF, PIXE, INAA, AAS, ICP/AES, IC, AC • 20.3 X 25.4 cm • Physical characteristics • Borosilicate glass fiber • High Particle Collection Efficiencies • Melts at > 500 oC • Low flow resistance

  20. Laboratory Analysis Methods Gravimetric analysis: mass IC:water soluble ionic species XRF and PIXE: the concentration of elements with atomic numbers ranging from 11(Na) to 92(Ur) AA: elements Flame ICP: elements, V, Cr, Mn, Fe, Zn, As, Se TOR (Thermal/Optical Reflectance Analysis): Element Carbon, Organic Carbon

  21. Selecting a Sampling System -5 steps- • To clearly define monitoring OBJECTIVES. • To determine the particle size fractions, chemical analyzes, sampling frequencies, and sampling duration. • To calculate the expected amount of deposit on the filter for each chemical species and compare it with detection limits for the analyses being considered. • To create, adapt, or purchase a sampling system that most cost-effective and reliable means of meeting the monitoring needs. • To create or adapt an operating procedure that specifies methods and schedules for inlet cleaning, filter transport and handling, calibration and performance tests, and record keeping.

  22. Reflection

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