Fabrication of halloysite nanotubes/polypyrrole nanocomposites for efficient removal of methyl orange

Halloysite nanotubes/polypyrrole (HNTs/PPy) nanocomposites were fabricated by in situ polymerization of pyrrole monomer in the presence of HNTs. The structures of the composites were analyzed by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis and transmission electron spectroscopy. Subsequently, the capability of HNTs/PPy nanocomposites on the removal of methyl orange from aqueous solution was systematically studied. The HNTs/PPy nanocomposites showed high adsorption capacity toward methyl orange and a maximum adsorption capacity of 214.6 mg/g at 25°C was achieved. The adsorption kinetics demonstrated a rapid methyl orange uptake by HNTs/PPy and the experimental data were well fitted to the pseudo-second-order model. The Langmuir and Freundlich models were employed to describe the adsorption isotherms, and the results presented that the equilibrium data obeyed both the Langmuir and Freundlich models. Thermodynamic parameters of Δ G ° and Δ H ° verified the spontaneous and exothermic nature of the methyl orange adsorption onto HNTs/PPy. Furthermore, the regeneration experiments revealed that HNTs/PPy nanocomposites could be reused after treated with hydrochloric acid solution, showing potential applications in purification of dyeing effluents.