Adsorption of emerging pollutants on functionalized multiwall carbon nanotubes

• Adsorption of emerging pollutants on functionalized carbon nanotubes.
• Functionalization of carbon nanotubes tunes adsorption properties.
• Different functional groups tested (N- and O-containing groups), and compared with parent MWCNTs.
• Main factors affecting these effects: hydrophobicity, π–π interaction, and morphology.

Adsorption of three representative emerging pollutants – 1,8-dichlorooctane, nalidixic acid and 2-(4-methylphenoxy)ethanol- on different carbon nanotubes was studied in order to determine the influence of the morphological and chemical properties of the materials on their adsorption properties. As adsorbents, multiwall carbon nanotubes (MWCNTs) without functionalization and with oxygen or nitrogen surface groups, as well as carbon nanotubes doped with nitrogen were used. The adsorption was studied in aqueous phase using batch adsorption experiments, results being fitted to both Langmuir and Freundlich models. The adsorption capacity is strongly dependent on both the hydrophobicity of the adsorbates and the morphology of the adsorbents. Thermodynamic parameters were determined observing strong interactions between the aromatic rings of the emerging pollutant and the nitrogen modified adsorbents.