A settling tube to determine the terminal velocity and size distribution of fluidized nanoparticle agglomerates


There are few techniques to measure in situ the size distribution and density of fluidized nanoparticle agglomerates. Visualization techniques, which are the most applied approach, currently have two important limitations: (1) they do not allow a continuous determination of the terminal velocity of the agglomerates, because it is necessary to stop the fluidization and (2) often, the agglomerates are tracked in very dilute zones of the bed, typically in the splash zone, where agglomerates are likely not representatives for the agglomerates in the whole bed. In this communication, we propose a sampling technique that allows to determine the size distribution and terminal velocity of fluidized agglomerates larger than ∼20 μm continuously, in situ, and allows to work with concentrations of agglomerates higher than other reported techniques.

This is a preview of subscription content, log in to check access.

Access options

Buy single article

Instant unlimited access to the full article PDF.

US$ 39.95

Price includes VAT for USA

Subscribe to journal

Immediate online access to all issues from 2019. Subscription will auto renew annually.

US$ 99

This is the net price. Taxes to be calculated in checkout.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6


  1. Birdal T (2011). matlabcentral/ fileexchange/30805- maximum-inscribed-circle- using-distance-transform. Accessed 02 Aug 2013

  2. Blott SJ, Pye K (2008) Particle shape: a review and new methods of characterization and classification. Sedimentology 55(1):31–63

  3. Bushell G, Yan Y, Woodfield D, Raper J, Amal R (2002) On techniques for the measurement of the mass fractal dimension of aggregates. Adv Colloid Interface 95(1):1–50

  4. de Martín L, Bouwman WG, van Ommen JR (2012) Two-level hierarchical structure in nano-powder agglomerates in gas media. In: Bulletin of the American Physical Society. 65th Annual Meeting of the APS Division of Fluid Dynamics, vol 57

  5. de Martín L, Bouwman WG, van Ommen JR (2013) Multidimensionality in fluidized nanopowder agglomerates. In: Powders and grains, Sydney, Australia

  6. Espin MJ, Valverde JM, Quintanilla MAS, Castellanos A (2009) Electromechanics of fluidized beds of nanoparticles. Phys Rev E 79:011304

  7. Fidleris V, Whitmore RL (1961) Experimental determination of the wall effect for spheres falling axially in cylindrical vessels. Brit J Appl Phys 12(9):490

  8. Goulas A, van Ommen JR (2013) Atomic layer deposition of platinum clusters on titania nanoparticles at atmospheric pressure. J Mater Chem A 1:4647–4650

  9. Hakim L, Blackson J, George S, Weimer A (2005a) Nanocoating individual silica nanoparticles by atomic layer deposition in a fluidized bed reactor. Chem Vap Depos 11(10):420–425

  10. Hakim LF, Portman JL, Casper MD, Weimer AW (2005b) Aggregation behavior of nanoparticles in fluidized beds. Powder Technol 160(3):149–160

  11. Ibaseta N, Biscans B (2010) Fractal dimension of fumed silica: Comparison of light scattering and electron microscope methods. Powder Technol 203(2):206–210

  12. Nam CH, Pfeffer R, Dave RN, Sundaresan S (2004) Aerated vibrofluidization of silica nanoparticles. AIChE J 50(8):1776–1785

  13. Quevedo JA, Pfeffer R (2010) In situ measurements of gas fluidized nanoagglomerates. Ind Eng Chem Res 49(11):5263–5269

  14. Quevedo JA, Pfeffer R, Shen Y, Dave RN, Nakamura H, Watano S (2006) Fluidization of nanoagglomerates in a rotating fluidized bed. AIChE J 52(7):2401–2412

  15. Quintanilla MAS, Valverde JM, Castellanos A, Lepek D, Pfeffer R, Dave RN (2008) Nanofluidization as affected by vibration and electrostatic fields. Chem Eng Sci 63(22):5559–5569

  16. Quintanilla MAS, Valverde JM, Espin MJ, Castellanos A (2012) Electrofluidization of silica nanoparticle agglomerates. Ind Eng Chem Res 51(1):531–538

  17. Shabanian J, Jafari R, Chaouki J (2012) Fluidization of ultrafine powders. Int Rev Chem Eng 4(1):16–50

  18. Valverde JM, Castellanos A (2006) Fluidization of nanoparticles: A modified Richardson–Zaki Law. AIChE J 52(2):838–842

  19. Valverde JM, Quintanilla MAS, Castellanos A, Lepek D, Quevedo J, Dave RN, Pfeffer R (2008a) Fluidization of fine and ultrafine particles using nitrogen and neon as fluidizing gases. AIChE J 54(1):86–103

  20. Valverde JM, Quintanilla MAS, Espin MJ, Castellanos A (2008b) Nanofluidization electrostatics. Phys Rev E 77:031301

  21. Wang X, Palero V, Soria J, Rhodes M (2006a) Laser-based planar imaging of nano-particle fluidization: part I: determination of aggregate size and shape. Chem Eng Sci 61(16):5476–5486

  22. Wang X, Palero V, Soria J, Rhodes M (2006b) Laser-based planar imaging of nano-particle fluidization: part II: mechanistic analysis of nanoparticle aggregation. Chem Eng Sci 61(24):8040–8049

  23. Yao W, Guangsheng G, Fei W, Jun W (2002) Fluidization and agglomerate structure of SiO2 nanoparticles. Powder Technol 124(1–2):152–159

  24. Yu Q, Dave RN, Zhu C, Quevedo JA, Pfeffer R (2005) Enhanced fluidization of nanoparticles in an oscillating magnetic field. AIChE J 51(7):1971–1979

  25. van Ommen JR, Sasic S, van der Schaaf J, Gheorghiu S, Johnsson F, Coppens MO (2011) Time–series analysis of pressure fluctuations in gas–solid fluidized beds: a review. Int J Multi Flow 37(5):403–428

  26. van Ommen JR, Valverde JM, Pfeffer R (2012) Fluidization of nanopowders: a review. J Nanopart Res 14(3):1–29

  27. Zemb T, Lindner P (2002) Neutron, X-rays and light. scattering methods applied to soft condensed matter. North Holland, Amsterdam

  28. Zhu C, Yu Q, Dave RN, Pfeffer R (2005) Gas fluidization characteristics of nanoparticle agglomerates. AIChE J 51(2):426–439

Download references


The authors would like to thank Maarten Weeber for his contribution in developing the settling tube.

The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant. Agreement no. 279632.

Author information

Correspondence to Lilian de Martín.

Electronic supplementary material

Below is the link to the electronic supplementary material.

MPG (3556 KB)

MPG (3556 KB)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

de Martín, L., Sánchez-Prieto, J., Hernández-Jiménez, F. et al. A settling tube to determine the terminal velocity and size distribution of fluidized nanoparticle agglomerates. J Nanopart Res 16, 2183 (2014).

Download citation


  • Aggregates
  • Density
  • Fluidization
  • Fractal dimension
  • Clusters
  • Nanoparticles