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Author

Baek, Jong-Beom
Center for Dimension-Controllable Organic Frameworks
Research Interests
  • Covalent Organic Frameworks (COFs), Carbon Nanotubes(CNTs), graphene, Energy Conversion and Storage

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Transport behavior of functionalized multi-wall carbon nanotubes in water-saturated quartz sand as a function of tube length

Cited 15 times inthomson ciCited 10 times inthomson ci
Title
Transport behavior of functionalized multi-wall carbon nanotubes in water-saturated quartz sand as a function of tube length
Author
Wang, YonggangKim, Jae-HongBaek, Jong-BeomMiller, Gary W.Pennell, Kurt D.
Keywords
Attachment; MWCNTs; Retention; Straining; Transport; Tube length
Issue Date
201209
Publisher
PERGAMON-ELSEVIER SCIENCE LTD
Citation
WATER RESEARCH, v.46, no.14, pp.4521 - 4531
Abstract
A series of one-dimensional column experiments was conducted to examine the effects of tube length on the transport and deposition of 4-ethoxybenzoic acid functionalized multi-wall carbon nanotubes (MWCNTs) in water-saturated porous media. Aqueous MWCNTs suspensions were prepared to yield three distributions of tube lengths; 0.02-1.3 mu m (short), 0.2-7.5 mu m (medium), and 0.2-21.4 mu m (long). Results of the column studies showed that MWCNT retention increased with increasing tube length. Nevertheless, more than 76% of the MWCNT mass delivered to the columns was detected in effluent samples under all experimental conditions, indicating that the functionalized MWCNTs were readily transported through 40-50 mesh Ottawa sand. Examination of MWCNT length distributions in the effluent samples revealed that nanotubes with lengths greater than 8 mu m were preferentially deposited. In addition, measured retention profiles exhibited the greatest MWCNT deposition near the column inlet, which was most pronounced for the long MWCNTs, and decreased sharply with travel distance. Scanning electron microscope (SEM) images showed that MWCNTs were deposited on sand surfaces over the entire column length, while larger MWCNT bundles were retained at grain intersections and near the column inlet. A mathematical model based on clean bed filtration theory (CBFT) was unable to accurately simulate the measured retention profile data, even after varying the weighting function and incorporating a nonuniform attachment rate coefficient expression. Modification of the mathematical model to account for physical straining greatly improved predictions of MWCNT retention, yielding straining rate coefficients that were four orders-of-magnitude greater than corresponding attachment rate coefficients. Taken in concert, these experimental and modeling results demonstrate the potential importance of, and need to consider, particle straining and tube length distribution when describing MWCNT transport in water-saturated porous media.
URI
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DOI
http://dx.doi.org/10.1016/j.watres.2012.05.036
ISSN
0043-1354
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