PMID- 22704927 OWN - NLM STAT- MEDLINE DCOM- 20121030 LR - 20211021 IS - 1879-2448 (Electronic) IS - 0043-1354 (Print) IS - 0043-1354 (Linking) VI - 46 IP - 14 DP - 2012 Sep 15 TI - Transport behavior of functionalized multi-wall carbon nanotubes in water-saturated quartz sand as a function of tube length. PG - 4521-31 LID - 10.1016/j.watres.2012.05.036 [doi] AB - 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 mum (short), 0.2-7.5 mum (medium), and 0.2-21.4 mum (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 mum 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. CI - Copyright (c) 2012 Elsevier Ltd. All rights reserved. FAU - Wang, Yonggang AU - Wang Y AD - Department of Civil and Environmental Engineering, Tufts University, 200 College Ave, 113 Anderson Hall, Medford, MA 02155, USA. FAU - Kim, Jae-Hong AU - Kim JH FAU - Baek, Jong-Beom AU - Baek JB FAU - Miller, Gary W AU - Miller GW FAU - Pennell, Kurt D AU - Pennell KD LA - eng GR - R01 ES016175/ES/NIEHS NIH HHS/United States GR - T32 ES012870/ES/NIEHS NIH HHS/United States GR - R01-ES016175/ES/NIEHS NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, U.S. Gov't, Non-P.H.S. DEP - 20120530 PL - England TA - Water Res JT - Water research JID - 0105072 RN - 0 (Nanotubes, Carbon) RN - 0 (Suspensions) RN - 059QF0KO0R (Water) RN - 14808-60-7 (Quartz) SB - IM MH - Computer Simulation MH - Models, Chemical MH - *Motion MH - Nanotubes, Carbon/*chemistry/ultrastructure MH - Particle Size MH - Quartz/*chemistry MH - Suspensions MH - Water/*chemistry PMC - PMC3395080 MID - NIHMS388477 EDAT- 2012/06/19 06:00 MHDA- 2012/10/31 06:00 PMCR- 2013/09/15 CRDT- 2012/06/19 06:00 PHST- 2011/11/02 00:00 [received] PHST- 2012/05/17 00:00 [revised] PHST- 2012/05/19 00:00 [accepted] PHST- 2012/06/19 06:00 [entrez] PHST- 2012/06/19 06:00 [pubmed] PHST- 2012/10/31 06:00 [medline] PHST- 2013/09/15 00:00 [pmc-release] AID - S0043-1354(12)00374-0 [pii] AID - 10.1016/j.watres.2012.05.036 [doi] PST - ppublish SO - Water Res. 2012 Sep 15;46(14):4521-31. doi: 10.1016/j.watres.2012.05.036. Epub 2012 May 30.