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

Ramanan, B., Holmes, W.M., Sloan, W.T. and Phoenix, V.R. (2012) Investigation of nanoparticle transport inside coarse-grained geological media using magnetic resonance imaging. Environmental Science and Technology, 46(1), pp. 360-366. (doi:10.1021/es2012726)

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Publisher's URL: http://dx.doi.org/10.1021/es2012726

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 T2-weighted images. A calibration protocol was then used to convert T2-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.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Phoenix, Dr Vernon and Holmes, Dr William and Sloan, Professor William
Authors: Ramanan, B., Holmes, W.M., Sloan, W.T., and Phoenix, V.R.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
College of Science and Engineering > School of Engineering > Infrastructure and Environment
College of Science and Engineering > School of Geographical and Earth Sciences > Geography
Journal Name:Environmental Science and Technology
Journal Abbr.:EST
Publisher:American Chemical Society
ISSN:0013-936X
ISSN (Online):1520-5851
Published Online:18 November 2011

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
500721Opening the black box: imaging nanoparticle transport with magnetic resonance imagingVernon PhoenixNatural Environment Research Council (NERC)NE/G010269/1School of Geographical and Earth Sciences
491431Magnetic resonance imaging of biofilm mass transport processes with gadolinium tracersVernon PhoenixEngineering & Physical Sciences Research Council (EPSRC)EP/G028443/1School of Geographical and Earth Sciences