title: Caged multiwalled carbon nanotubes as the adsorbents for affinity-based elimination of ionic dyes.
abstract: Multiwalled carbon nanotubes (MWCNTs) were used as the active elements for the first time for affinity-based elimination of ionic dyes. MWCNTs were encapsulated in cross-linked alginate (ALG) microvesicles using Ba2+ as the bridging ion. The Ba2+-alginate matrix constitutes a cage which holds the physically trapped MWCNTs. The cage carries negative charges on its surface. The cage restricts the access of anions of large molecular weight, such as humic acids, because of electrostatic repulsion. The cage also restricts the access of colloids of large size, because of size exclusion. Ionic dyes partition into the cage and then are captured by MWCNTs probably on the basis of van der Waals interactions occurring between the hexagonally arrayed carbon atoms in the graphite sheet of MWCNTs and the aromatic backbones of the dyes. As a result of these interactions the target species, namely, the ionic dyes, are eliminated efficiently by the MWCNTs of Ba2+-ALG/MWCNT composite adsorbents. The adsorptive capacities for elimination of acridine orange, ethidium bromide, eosin bluish, and orange G (the model species used for this study) were found as high as 0.44, 0.43, 0.33, and 0.31 micromol, respectively, for 1.0 mg of the caged MWCNTs. Adsorptive experiments with carbon nanofibers and activated carbons as the adsorbents were also performed. The MWCNT-based adsorbents provided the best capability for the affinity-based elimination of these targeted species. Biocompatibility experiments performed in vitro and in vivo provided promising results, suggesting potential applications of the caged MWCNTs in in situ environmental remediation.
authors.affiliation: Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan. hu@ees.hokudai.ac.jp
authors.forename: Bunshi
authors.initials: B
authors.lastname: Fugetsu
authors.forename: Shuya
authors.initials: S
authors.lastname: Satoh
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Shiba
authors.forename: Taeko
authors.initials: T
authors.lastname: Mizutani
authors.forename: Yong-Bo
authors.initials: YB
authors.lastname: Lin
authors.forename: Norifumi
authors.initials: N
authors.lastname: Terui
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Nodasaka
authors.forename: Katsushi
authors.initials: K
authors.lastname: Sasa
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Shimizu
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Akasaka
authors.forename: Masanobu
authors.initials: M
authors.lastname: Shindoh
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Shibata
authors.forename: Atsuro
authors.initials: A
authors.lastname: Yokoyama
authors.forename: Masanobu
authors.initials: M
authors.lastname: Mori
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Tanaka
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Sato
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Tohji
authors.forename: Shunitz
authors.initials: S
authors.lastname: Tanaka
authors.forename: Norio
authors.initials: N
authors.lastname: Nishi
authors.forename: Fumio
authors.initials: F
authors.lastname: Watari
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D004396:Coloring Agents / Q000302:isolation & purification*; D004867:Equipment Design; D036103:Nanotechnology; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*
chemical_list: D004396:Coloring Agents; D014874:Water Pollutants, Chemical; D002244:Carbon