Meetprincipes voor meting van nanodeeltjes in de lucht

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1 Meetprincipes voor meting van nanodeeltjes in de lucht Andreas Schmidt-Ott Nanostructured Materials, Faculty of Applied Sciences, TU Delft

2 Qauntum dots van verschillende afmetingen geven licht in verschillende kleuren

3 TNW Nanosafety Guidelines Authors: Dick Hoeneveld Roel Kamerling Jelan Kuhn John Nijenhuis Andreas Schmidt-Ott

4 When is Nanotoxicity possible?

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6 Measurement of particles in gases: Conventional techniques

7 Particulate Mass Measurement: β Absorption ln( I I 0 ) K Q t b c m Insensitive to nanoparticles!

8 Mass measurement: Tapered Element Oscillator Microbalance (TEOM) (H. Patashnik, G. Ruprecht, Proceedings of Advances in Particulate Sampling and Measurement, ed. By W.B. Smith, p. 264, EPA-600/ , U.S. Environmental Protection Agency, 1980) f = K Q t q c m Insensitive to nanoparticles!

9 Optical particle counters Application range: d p > 100 nm Insensitive to nanoparticles!

10 Environmental Dust Monitor Instrument based on light scattering for measurement of PM 10, PM 2.5 and PM 1 Insensitive to nanoparticles!

11 Size distribution of typical atmospheric aerosol in terms of volume (mass), surface and number distribution

12 Condensation Nucleus Counter Counts nanoparticles > 5 nm Particle number concentration

13 Condensation Nucleus Counter (example) n-butanol storage bottle Display: counts ( #/cm 3 ) Aerosol inlet Adapted from: Expensive!

14 Relevant dose for toxicity of nanodispersed material should be measured in: ~ Mass(Volume)? ~ Surface? ~ Number? The joint surface area of particles deposited in the lung most frequently correlates with the toxic effects Current measurement technology gives access to Number concentration assumptions Diameter Surface

15 Aerodynamic Particle Sizer (TSI Inc.) Aerodynamic diameter distribution Insensitive to nanoparticles!

16 Cascade impactor for - size separation - determination of size distribution Adapted from Particle Technology Insensitive to nanoparticles!

17 Size Classification by Mobility Separation (Differential Mobility Analyzer, DMA) With charger and condensation nucleus counter: SMPS system Charger Number concentration for each size interval Condensation Nucleus Counter

18 Example DMA + CNC setup Adapted from: Expensive devices Research instruments

19 Size distribution of Diesel exhaust particles emitted by a heavy-duty engine with and without particle trap measured by mobility analysis

20 Measurement of particles in gases: Newer monitoring techniques

21 Measurement of particle concentration by purely electrical means I Charger-Electrometer Aerosol Monitor (A. Schmidt-Ott, Th. Kauffeldt, Assessment of Particulate Air Pollution by New Sensor Concepts VDI Bericht No. 1443, pp. 517, VDI Verlag, Dusseldorf, 1999) Aerosol Diffusion Charger I: Sensor output (current) N: Particle concentration D P : Particle diameter Aerosol Electrometer D P (max) = x P 0 I const D dn I with x= 1...2

22 TSI AEROTRAK 9000 monitor (measures nanoparticle exposure in terms of active surface ) Rather crude measure of the particle surface

23 Charger-Electrometer Aerosol Monitor

24 Photoelectric Aerosol Sensor for Selective Measurement of Soot Nanoparticles A. Kurniawan, A. Schmidt-Ott, 2005 hν Soot Mass

25 A. Kurniawan, A. Schmidt-Ott, 2005: 5% of the passenger cars produce 43% of the particulate pollution!

26 Measurement of particle concentration by purely electrical means II (H. Burtscher, A. Schmidt-Ott, European patent EP B1) =Principle of Nanocheck (Grimm), Nanotracer (Philips Aerasense) V ( t) V Aerosol Charger Aerosol I( t) I 0 t I I( t) Aerosol Electrometer I,, 0 I N DP I(t): Sensor output (current) N: Particle concentration D P : Particle diameter

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28 The Nanotracer

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30 Example DMA + CNC setup Adapted from: Expensive devices Research instruments

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32 Matter Engineering A.G. Wohlen, Switzerland

33 Preview on Nanoparticle Monitors A. Dahl, A. Gudmundsson and M. Bohgard European Aerosol Conference 2009, Karlsruhe

34 Problems in Monitoring Airborne Nanoparticles on the Workfloor (will be dealt with within NanoNext by TU Delft and TNO starting ) 1) Process particles must be distinguished from background particles. Solutions can be based on The difference in size Local differences in particle concentration, or The difference in composition 2) Selective detection of poorly soluble particles 3) Most nanoparticles from processes are strongly agglomerated. Monitoring principles that give an estimate of the primary particle size are desired D A D P

35 Conclusions Conventional particulate mass measurement techniques are not suitable for nanoparticles Parameters more suitable than mass (number, surface, diameter) can be measured by conventional aerosol technology Simple monitors for real-time assessment of nanoparticles in the air deliver The number concentration The mean diameter A surface related quantity (under certain conditions) Remaining challenges (will be addressed within the Nano-Next program from ): Distinction of particles produced on the work floor from the background Detection of nanoparticles that are part of large agglomerates Selective detection of poorly soluble nanoparticles There is no international consensus on which physical parameters are to be used Mean diameter and number concentration? Total surface area? PM 10, PM 2.5, PM 1.0, PM 0.25, PM 0.1, PM 0.025, PM 0.01, PM ?