Particle sizing by multi-wavelength photo-sedimentation

Transcription

1 Particle sizing by multi-wavelength photo-sedimentation Dietmar Lerche, Prof. Dr. Dr. LUM Berlin, Germany 1. Introduction 2. Application broadening by multi-wavelength STEP-Technology 3. PSD with no information of optical particle properties (see also Lerche: Comprehensive particle characterization by homgeneous-start centrifugal sedimentation technique, this workshop) 2015 LUM GmbH 1

2 STEP-Technology: In-situ visualization of separation behavior Meniscus last = Green Cell Bottom Calibration/Validation service provided 1 = Red Qualitative: Fingerprints Quantitative: Instability Index, Fronttracking, Integration Particle velocity and size 2016 LUM GmbH

3 STEP - Fingerprints Suspension monomodal monodisperse Suspension tetramodal monodisperse Suspension polydisperse Suspension particle particle - interaction Emulsion rather monodisperse Suspoemulsion flotation and sedimentation First transmission profil: red Last transmission profil: green 2016 LUM GmbH

4 Concentration determination: Physical basics I 0 I(p,t) Concentration change position resolved E d Mie + Aperture i 2 3 Kext, x i i Lambert-Beer-Law - ln I(p,t) = E ~ a(p,t). d I O by optical technique a i d e. a. d e = f (l, m, size, shape) diluted & semidiluted NIR: mostly only scattering VL: adsorption and scattering X-Ray: mostly only adsorption 2016 LUM GmbH 4

5 Calculated Extinction E cal [-] Comparison of experimental extinctions with theoretical extinctions (NIR) Silica 280 nm LS Silica 280 nm LF Silica 545 nm LS Silica 545 nm LF Silica 1550 nm LS Silica 1550 nm LF Latex 503 nm LS Latex 503 nm LF Experimental Extinction E exp [-] 2016 LUM GmbH

6 Application broadening by shorter wave length (Visualization by visible light) Extinction = f (Detection wavelength) Concentration 0.01 % v/v; refractive index : particle 1.45, fluid 1.33; optical path length 10 mm; aperture angle LUM GmbH 6

7 General properties and rules BLUE NIR 470 nm 865 nm In the visible range of naked eye Colour of particles and continuous phase may play a role (absorption) Sensitive also to very small particles Recommended for samples with initial transmission >80 % Different information compared to naked eye observation Independent of colour Used for large, medium and small particles Recommended for samples with initial transmission of 0-80% 2016 LUM GmbH 7

8 Classic STEP-Technology Visualization of particle concentration by NIR Visible Light NIR Light? Meniscus Sediment Conclusion: NIR transmission depends almost only on scattering; Intensity does not depend on colour of continouse phase 2015 LUM GmbH

9 Sensitivity of STEP - Technology : NIR, path length Naked eye can not discriminate between milk products of different fat content 0.18% 0.45 % 0.9 % 1.8 % STEP Technology (NIR) can easily discriminate between fat contents from 0.01 % - 5% integral transmission [%] 30 2 mm 10 mm Transmission at zero time Creaming and sedimentation in situ during centrifugation 2mm cells, Original concentration % fat 2015 LUM GmbH

10 Simple selection of the desired wavelength 2015 LUM GmbH 10

11 Transmission profiles of silica nanoparticles measured at different wavelengths (LUMiSizer) NIR Light Blue Light DT NIR DT Blue DC = DC Conclusion: Blue light provides higher sensitivity Best for low concentration and nanoparticles 2015 LUM GmbH

12 Extinction profiles of 1 µm silica measured simultaneously at different wavelengths (LUMiReader) blue red NIR E NIR /E blue 2015 LUM GmbH 12

13 Turbidity Index Mixtures of differently sized silica at different ratios and turbidity index extinction NIR / extinction blue % 0.10% 0.15% Superposition of extinctions of individual particle fractions Ratio 1 µm / 0.19 µm Silica 0 % 1 µm 100 % 1 µm 2015 LUM GmbH 13

14 Effect of agglomeration for 45 nm Ludox stable Aqueous suspension Agglomeration at 3.5 g/l NaCl 2015 LUM GmbH 14

15 Turbidity Index Agglomeration of 45 nm Ludox monitored by turbidity index 3.5 g/l NaCl Difference between NIR and the blue increases over time with higher NaCl concentration indicating flocculation 2015 LUM GmbH 15

16 Dispersibility of Alu C - Effect of dispersion procedure Classification of separation behavior by fingerprints only vortex 15 min ultrasonic b. 1 min sonicatio n 3 min sonicatio n 10 min sonicatio n LUMiSizer: 2300 g 43 min 20 C Sobisch, Lerche: Dispersion Letters 6 (2015) LUM GmbH 16

17 Dispersibility of Alu C - Effect of dispersion procedure Classification of separation behaviour by turbidity index TI = I 0;470 /I 0;870 Experimental data: MWL- LUMiSizer: 2300 g 120 s 20 C 2015 LUM GmbH 17

18 1st derivative of "B" [T/m] B [T] LUMiReader-Mag: In-situ visualization of MP-migration due to magnetic and/or gravity fields magnet discs at bottom Opt. window 40 mm Resolution < 30 µm DT = 0.1 s to hours 3 Wavelengthes 1000 Profiles Different opt. cells 30 C 60 C Operation and quantification by SEPView NeoDeltaMagnet (NdFeB), IBSMagnets NE155; Magnet disc: D=15,0 mm, h=5,0 mm X [mm] X [mm] B 0.1T db/dx 19.4 T/m Averaged over probe height O. Mykhaylova, D. Lerche et al., IEEE Magnetic Letters, 6 (2015), Open source 2015 LUM GmbH

19 Integral extinction Integral extinction Determination of magnetophoretic velocity distribution MP 11, monodisperse No magnetic field Magnetic field: T, 19.4 T/m Time (s) LUMiReader-Mag Data Time (s) v (µm/s) 2015 LUM GmbH

20 870 nm 630 nm 410 nm Normalized Integral Extinction A Magnetophoretic velocity analyzed at different wavelengths B MP 1, polydisperse B 0.16T db/dx 33.5T/m Averaged over sample height l = 410 nm l = 630 nm l = 870 nm Time (s) 2015 LUM GmbH

21 Cosmetic powder in aqueous suspension Particle size distribution according to ISO Entire nm 2. Supernatant of first run removed and measured nm to detect and analyze the fine particles The Next STEP in Dispersion Analysis LUM GmbH 21

22 Concentration determination: Physical basics I 0 I(p,t) Concentration change position resolved d Mie + Aperture 3 K ext, E i 2 x i i Lambert-Beer-Law - ln I(p,t) = E ~ a(p,t). d I O a by optical technique i d e = f (l, n, size, shape) diluted & semidiluted by X-Ray technique E i µ i a i d m = f (l, atomic number) m does not depend on n, size or shape! up to very heigh concentrations! LUM GmbH

23 STEP-Technology by X-Ray source: Molybdenum X-Ray tube anode power: 40kV and 500µA, focal spot size: 50 x 50 µm monochromator: HOPG (pyrolytic graphite) X-ray sensor: FOP (fibre optical plate) coupled CCD line Lerche et al., Proceedings Filtech 2015, L1-Dispersion Separation Analysis 2016 LUM GmbH 23

24 Real Time: Separation of varnish with mixed filler (MoS 2 /graphite) X-Ray transmission by LUMiReader X-Ray LUM GmbH

25 Real Time: Phase separation of adhesives with fillers Data: LUMiReader X-Ray 2016 LUM GmbH 25

26 Sediment density profiling by X-ray Concentration gradients at applied compressional pressures Quartz, stable Limestone, ph 12, flocculated TOP BOTTOM 2016 LUM GmbH

27 Suspension: 10 % Quartz (500 nm 10 µm) + 30 % Koestrosol (15 nm) before centrifugation after centrifugation LUMiSizer 2300 g, 10 min, 25 C Light Transmission 2016 LUM GmbH 27

28 Average Transmission in % Suspension:10 % Quartz + 30 % w/w NP X-Ray detection of nano particles in supernatant Attenuation of nanoparticles Quartz sediment Position in mm 2016 LUM GmbH 28

29 Multi-wavelength STEP: Conclusion VL allows to broaden the application fields of STEP-Technology compared to NIR VL wavelengths: Very transparent and diluted samples Nanosized particles Turbidity index allows to follow up effectively flocculation, dispersion processing etc. ( no particle sizing necessary) Detection of nanoparticles in supernantant X-Ray High concentrated samples Consolidation, dewaterability etc. Structures in sediments, filter cakes etc. Stability of non-transparent samples Detection of dispersing quality, agglomerates, flocs, UV-Blockers in original products LUM GmbH

30 Classical PSD analysis according to ISO T Spatially and time resolved transmission profiles E Time curve of extinction Constant position E ln(t) t meas r meas r t Dr v s E ln(t) E Q size distribution Radial extinction profile Constant time Q 3 Q ext Dr v s t meas conversion Q ext Q 3 requires optical model C ext (x Stokes ) x Stokes 2016 LUM GmbH

31 Approach for a parameter-free Q 3 -determination by photocentrifuges Photometric measurement New approach Light particle C ext K ext x funct ( l Stokes v ) K ext C A ext proj funct ( m rel x, ) l extinction efficiency K ext facilitates comparison among different size/shape classes and wavelengths = optical model influences of x and λ on K ext are equivalent we can derive K ext (l) by measuring q ext (x,l) at different wavelengths 2016 LUM GmbH

32 Summenverteilung Q 3-distribution by multiwavelength appraoch of mixtures of different ratios of SediTest 170 nm & 550 nm (Silica), no Mie correction applied 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 Q_3 (1:1) Q_3 (2:1) Q_3 (4:1) Q_3 (8:1) Q_Int 455 nm (1:1) Q_Int 455 nm (2:1) Q_Int 455 nm (4:1) Q_Int 455 nm (8:1) Q_Int 870 nm (1:1) Q_Int 870 nm (2:1) Q_Int 870 nm (4:1) Q_Int 870 nm (8:1) Volume weigted by MWLappraoch Extinction weighted distribution at different WL xp in nm

33 No optical model: Conclusion MW-analysis for computing Q 3 with no RI values promising results for minerals (SiO 2, Al 2 O 3, TiO 2 ) and Au approach works fine for polydisperse samples, even for non-spherical particles approach fails (not shown here) for multiple narrow modes how to proceed? expand investigation to other materials (e.g. carbon black) look more systematically on non-spherical particles LUM workshop 2016, Berlin Babick: MW-analysis of LUMiSizer data slide 33 of 24

34 Thank you for your kind attention!!! A. Schmidt, F. Babick (TU Dresden) K. Obata, Y. Mori Doshisha Univ. Kyoto More Information: See exhibition by Adaptive Instruments (Colin Jenkins) LUM GmbH