A study on the adsorption of chromium (VI) from aqueous solutions on the alginate-montmorillonite/polyaniline nanocomposite

In this study, batch adsorption system using a novel organic/inorganic hybrid of biopolymer, nanoclay and conducting polymer viz. alginate-montmorillonite/polyaniline (Alg-MMT/PANI) nanocomposite was investigated to describe the adsorption of hexavalent chromium (Cr(VI)) from aqueous solutions. The Alg-MMT/PANI nanocomposite was synthesized by chemical oxidative polymerization of aniline in the presence of alginate-montmorillonite nanocomposite dispersion. The structure and morphology of the prepared nanocomposite was characterized utilizing Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. In the adsorption studies, the effects of initial concentration of Cr(VI), pH, adsorbent dose, and contact time were investigated. Furthermore, the adsorption kinetics studies showed that the adsorption process followed pseudo-second-order model. Also, the investigation of adsorption isotherms revealed that the equilibrium adsorption data were well described by the Freundlich isotherm model. Based on this model, the adsorption capacity, K-f, was calculated to be 29.89mgg(-1). Thermodynamic parameters indicated that the adsorption of Cr(VI) by Alg-MMT/PANI nanocomposite is an endothermic process.