Adsorption of methylene blue onto chitosan–montmorillonite/polyaniline nanocomposite

Eco-friendly adsorbent of chitosan–montmorillonite/polyaniline (CH–Mt/PANI) nanocomposite was synthesized by the intercalation of CH into Mt through ion-exchange process followed by the impregnation of aniline. Then in-situ polymerization of aniline using ammonium peroxydisulfate as an oxidant yielded a conducting polymer, polyaniline, as an additional component. The composite with polyaniline salt was also converted to corresponding CH–Mt/PANI base nanocomposite. The composites were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, thermal gravimetric analysis and electron microscopy and subsequently used for the removal of methylene blue from aqueous solutions. The composite with polyaniline base proved to be better dye adsorbent than that with polyaniline salt and was therefore investigated in detail. The adsorption of the dye onto CH–Mt/PANI base nanocomposite follows the pseudo second-order kinetics and it is well described by Temkin isotherm model. Moreover, the intraparticle diffusion was found to play a significant role in the adsorption mechanism. The maximum adsorption capacity was estimated to be 111 mg g−1, exceeded the adsorption capacities of the individual precursors.