Investigation of nanoparticle transport inside coarse-grained geological media using magnetic resonance imaging

B. Ramanan, W. M. Holmes, W. T. Sloan, V. R. Phoenix

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Quantifying nanoparticle (NP) transport inside saturated porous geological media is imperative for understanding their fate in a range of natural and engineered water systems. While most studies focus upon finer grained systems representative of soils and aquifers, very few examine coarse-grained systems representative of riverbeds and gravel based sustainable urban drainage systems. In this study, we investigated the potential of magnetic resonance imaging (MRI) to image transport behaviors of nanoparticles (NPs) through a saturated coarse-grained system. MRI successfully imaged the transport of superparamagnetic NPs, inside a porous column composed of quartz gravel using T 2-weighted images. A calibration protocol was then used to convert T 2-weighted images into spatially resolved quantitative concentration maps of NPs at different time intervals. Averaged concentration profiles of NPs clearly illustrates that transport of a positively charged amine-functionalized NP within the column was slower compared to that of a negatively charged carboxyl-functionalized NP, due to electrostatic attraction between positively charged NP and negatively charged quartz grains. Concentration profiles of NPs were then compared with those of a convection-dispersion model to estimate coefficients of dispersivity and retardation. For the amine functionalized NPs (which exhibited inhibited transport), a better model fit was obtained when permanent attachment (deposition) was incorporated into the model as opposed to nonpermanent attachment (retardation). This technology can be used to further explore transport processes of NPs inside coarse-grained porous media, either by using the wide range of commercially available (super)paramagnetically tagged NPs or by using custom-made tagged NPs.

Original languageEnglish
Pages (from-to)360-366
Number of pages7
JournalEnvironmental Science and Technology
Volume46
Issue number1
Early online date18 Nov 2011
DOIs
Publication statusPublished - 3 Jan 2012
Externally publishedYes

    Fingerprint

Keywords

  • nanoparticle transport
  • engineered water systems
  • riverbeds
  • urban drainage systems
  • magnetic resonance imaging
  • MRI
  • superparamagnetic nanoparticles
  • coarse-grained porous media

Cite this