title: Influence of surface oxides on the adsorption of naphthalene onto multiwalled carbon nanotubes.
abstract: As greater quantities of carbon nanotubes (CNTs) enter the environment, they will have an increasingly important effect on the availability and transport of aqueous contaminants. As a consequence of purification, deliberate surface functionalization, and/or exposure to oxidizing agents after release to the environment, CNTs often contain surface oxides (i.e., oxygen containing functional groups). To probe the influence that surface oxides exert on CNT sorption properties, multiwalled CNTs (MWCNTs) with varying oxygen concentrations were studied with respect to their sorption properties toward naphthalene. For pristine (as-received) MWCNTs, the sorption capacity was intermediate between that of a natural char and a granular activated carbon. Sorption data also reveal that a linear relationship exists between the oxygen content of MWCNTs and their maximum adsorption capacity for naphthalene, with 10% surface oxygen concentration resulting in a roughly 70% decrease in maximum adsorption capacity. The relative distribution of sorption energies, as characterized by Freundlich isotherm exponents was, however, unaffected by oxidation. Thus, the data are consistent with the idea that incorporated surface oxides create polar regions that reduce the surface area available for naphthalene sorption. These results highlight the important role of surface chemistry in controlling the environmental properties of CNTs.
authors.affiliation: Department of Geography and Environmental Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.
authors.forename: Hyun-Hee
authors.initials: HH
authors.lastname: Cho
authors.forename: Billy A
authors.initials: BA
authors.lastname: Smith
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Wnuk
authors.forename: D Howard
authors.initials: DH
authors.lastname: Fairbrother
authors.forename: William P
authors.initials: WP
authors.lastname: Ball
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009281:Naphthalenes / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D037742:Nanotubes, Carbon; D009281:Naphthalenes; D010087:Oxides; D014874:Water Pollutants, Chemical; C031721:naphthalene; D002244:Carbon