Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high-pressure suspensions

Daniel To, Rajesh Dave, Xiaolong Yin, Sankaran Sundaresan

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53 Scopus citations


Deagglomeration of suspensions of alumina and titania nanopowders (i.e., nanoparticle aggregates) via rapid expansion of supercritical suspensions (RESS) or high-pressure suspensions (REHPS) was studied. The size distribution of fragmented nanopowders was characterized by online Scanning Mobility Particle Spectrometer (SMPS) and Aerodynamic Particle Sizer (APS), and by offline Scanning Electron Microscopy (SEM). SMPS and SEM measurements indicate that the average agglomerate sizes were well below 1 lm, consistent with the length scales observed in our complementary RESS/REHPS mixing experiments using alumina and silica nanopowders. The APS measurements, on the other hand, were affected by reagglomeration during sampling and yielded an agglomerate size range of 1 to 3 lm. Analysis of the RESS/ REHPS process through compressible flow models revealed that both the shear stress in the nozzle and the subsequent impact of the agglomerates with the Mach disc in the free expansion region can lead to micron or sub-micron level deagglomeration.

Original languageEnglish (US)
Pages (from-to)2807-2826
Number of pages20
JournalAIChE Journal
Issue number11
StatePublished - Nov 2009

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Environmental Engineering
  • General Chemical Engineering


  • Characterization of nanoparticle agglomerates
  • Deagglomeration of nanoparticle agglomerates
  • Nanoscale mixing
  • Rapid expansion
  • Supercritical fluids


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