Methylene blue removal by carbon nanotube-based aerogels

In this study, carbon nanotube-based porous structures were utilized as novel adsorbents for removal of methylene blue (MB) from aqueous solutions. The adsorbents were fabricated from CNT-contained resorcinol/formaldehyde gels which were subsequently freeze-dried and thermally treated under an inert atmosphere. The densities of the as-prepared SWCNT and MWCNT aerogels were 0.140 g/cm(3) and 0.149 g/cm(3) and the specific surface areas were 197 m(2)/g and 537 m(2)/g, respectively. The investigation on the adsorption behavior of these aerogels revealed that the MB adsorption kinetics followed a pseudo-second order model, and the equilibrium data were best described by Freundlich isotherm model. Moreover, the calculated thermodynamic parameters indicated that the process was spontaneous and endothermic. Our experimental results suggest that the advantage of using these porous adsorbents is not only their effective performances due to their compositional and structural properties, but also their facile separation from the solutions due to their macroscopic dimensions. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.