Evaluation of assisting methods on fluidization of hydrophilic nanoagglomerates by monitoring moisture in the gas phase

Jose A. Quevedo, Jürgen Flesch, Robert Pfeffer, Rajesh Dave

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13 Scopus citations


Agglomerates of nanoparticles were fluidized conventionally and under the influence of assisting methods such as vibration and/or moving magnetic particles. The adsorption/desorption rate of moisture of fluidized hydrophilic nanopowders was monitored during humidification/drying of the powder in order to find their adsorption isotherms at room temperature and to evaluate the assisting methods. Adsorption isotherms were verified by a gravimetric method. The nanopowders studied were Degussa Aerosil® 200 and Aerosil® 90, which were chosen because of their different fluidization behaviors. The moisture level in the nitrogen gas used to fluidize the powders was monitored on-line by using humidity sensors upstream and downstream of the fluidized bed. Moisture was added to the fluidizing nitrogen by bubbling it through water. The amount of moisture adsorbed/desorbed by the powders was obtained by integration of the time dependant moisture concentration. It was found that when the bed of powder is assisted during fluidization, the mass transfer between the gas and the nanopowder, as measured by the amount of moisture adsorbed/desorbed, is larger than when the powder is conventionally fluidized. Vibration assistance was found to be more effective for Aerosil® 200, an APF type nanopowder, but magnetic assistance was needed for Aerosil® 90 in order to break down the very large agglomerates formed in this ABF nanopowder.

Original languageEnglish (US)
Pages (from-to)2608-2622
Number of pages15
JournalChemical Engineering Science
Issue number9
StatePublished - May 2007

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering


  • Adsorption
  • Drying
  • Fluidization
  • Mass transfer
  • Nanopowders
  • Particle processing


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