Transport of rodlike colloids through packed beds

Michael B. Salerno, Matt Flamm, Bruce E. Logan, Darrell Velegol

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


The effect of colloid shape on filtration rates in porous media was examined by constructing particles with different aspect ratios and measuring their retention in packed beds. Spherical polystyrene latex microspheres (1.0-μm diameter) were heated, stretched to the desired aspect ratio (2:1 and 3:1, with a 1:1 control), and quickly cooled. These particles were injected into minicolumns containing glass beads (40-μm diameter) in solutions at two different ionic strengths (IS = 1 and 100 mM). The measured retentions increased with aspect ratio in both IS solutions. The ζ-potentials for all three aspect ratios we re indistinguishable, and no charge nonuniformity was measured for any of the samples. Thus, the data support that changes in retention resulted from the different aspect ratios rather than from different surface chemistries. Interpretation of the retention data in terms of a collision efficiency (a) showed an increase with aspect ratio in both IS solutions, and for 1 mM the α increased from 0.011 (1:1) to 0.095 (2:1) to 0.26 (3: 1). These results demonstrate for the first time the direct impact of particle shape on retention in porous media. Our findings have important implications for the transport of particles with high aspect ratios, such as rod-shaped bacteria, and for the modeling of such transport.

Original languageEnglish (US)
Pages (from-to)6336-6340
Number of pages5
JournalEnvironmental Science and Technology
Issue number20
StatePublished - Oct 15 2006

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Environmental Chemistry


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