Polypyrrole nanofibers as a high-efficient adsorbent for the removal of methyl orange from aqueous solution

The polypyrrole (PPy) nanofibers were synthesized by an oxidative template assembly route and evaluated as an adsorbent for the removal of a typical anionic dye (methyl orange, MO) from aqueous solution. The as-synthesized PPy nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and N-2 sorption. The effects of contact time, initial MO concentration, temperature, and initial solution pH on the adsorption of MO onto PPy nanofibers have been investigated. Experimental results showed that the PPy nanofibers possessed excellent adsorption capacity for MO (169.55 mg/g) at 25 degrees C. The pseudo-second-order model could fit to the experimental data better comparing with the pseudo-first-order kinetic adsorption model. And isotherm data fitted well to the Langmuir isotherm model. Thermodynamic study revealed that the adsorption process was endothermic and spontaneous in nature. In addition, the possible adsorption mechanism was proposed based on the experimental results. And the selective adsorption behaviors of the polypyrrole nanofibers towards different organic dyes were explored and the re-use of adsorbate was tested. (C) 2015 Elsevier Ltd. All rights reserved.