Ultrafast removal of Cr(VI) ions using polyamine modified carbon nanotubes

Background: Hexavalent chromium (Cr(VI)) is a highly hazardous substance due to its carcinogenicity, mutagenicity, genotoxicity, and bioaccumulation through food chains. Therefore, how to remove Cr(VI) fastly is an important issue. Method: Polyamine modified carbon nanotubes (PA-CNTs) were synthesized by leveraging a facile grafting condensation modification strategy to remove aqueous Cr(VI). The PA-CNTs was characterized by FTIR, XPS, TGA, SEM and TEM, respectively. The adsorption and desorption behavior of PA-CNTs to Cr(VI) was studied. Significant findings: The PA-CNTs showed an extremely fast Cr(VI) adsorption rate with 95% of Cr(VI) was removed within 3 min. In addition, the prepared PA-CNTs adsorbents displayed a maximum Cr(VI) adsorption capacity of 168.54 mg g-1, benefiting from the newly introduced surface amine groups. The adsorption process is well described by the pseudo-second-order model. Significantly, the synthesized PA-CNTs adsorbents had a high Cr(VI) adsorption capacity of 392.78 mg g-1 in the presence of Rhodamine B, along with an excellent reusability. The enhanced Cr(VI) adsorption performance can be attributed to the strong electrostatic interactions, complexation, as well as oxidation-reduction between Cr(VI) and PA-CNTs. (c) 2022 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.