title: Interaction of phenol and dopamine with commercial MWCNTs.
abstract: We report the adsorption of phenol and dopamine probe molecules, from aqueous solution with NaCl, on commercial multiwall carbon nanotubes (MWCNT) and on their carboxylated derivative. The nanotubes were fully characterized by high resolution transmission electron microscopy (HRTEM), small angle X-ray scattering (SAXS), potentiometric titration, electrophoretic mobility, and nitrogen adsorption (77K) measurements. The experimental pollutant isotherms, evaluated using the Langmuir model, showed that only 8-12% and 21-32% of the BET surface area was available for phenol and dopamine, respectively, which is far below the performance of activated carbons. Influence of the pH was more pronounced for the oxidized MWCNT, particularly with dopamine. The strongest interaction and the highest adsorption capacity occurred at pH 3 with both model pollutants on both types of nanotubes. Although the surface area available for adsorption is far lower in MWCNTs than in activated carbons, it is nonetheless substantial. In particular, delayed release of toxic molecules that are either adsorbed on the surface or trapped in the inner bore of such systems could constitute an environmental hazard. The need for further adsorption studies with regard to their environmental aspects is therefore pressing, particularly for MWCNTs in their functionalized state.
authors.affiliation: Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, Hungary.
authors.forename: Ajna
authors.initials: A
authors.lastname: Tóth
authors.forename: Andrea
authors.initials: A
authors.lastname: Törocsik
authors.forename: Etelka
authors.initials: E
authors.lastname: Tombácz
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Oláh
authors.forename: Marc
authors.initials: M
authors.lastname: Heggen
authors.forename: Chengliang
authors.initials: C
authors.lastname: Li
authors.forename: Erwin
authors.initials: E
authors.lastname: Klumpp
authors.forename: Erik
authors.initials: E
authors.lastname: Geissler
authors.forename: Krisztina
authors.initials: K
authors.lastname: László
mesh_terms: D000327:Adsorption; D004298:Dopamine / Q000737:chemistry*; D024202:Electrophoretic Mobility Shift Assay; D006863:Hydrogen-Ion Concentration; D046529:Microscopy, Electron, Transmission; D037742:Nanotubes, Carbon; D019800:Phenol / Q000737:chemistry*; D012542:Scattering, Radiation; D013816:Thermodynamics
chemical_list: D037742:Nanotubes, Carbon; D019800:Phenol; D004298:Dopamine