Fabrication and Characterization of Dextrin-g-Polypyrrole/Graphene Oxide Nanocomposite for Effective Removal of Pb (II) and Methylene Blue Dye from Aqueous Solutions

Dextrin-g-polypyrrole/graphene oxides (PDGP/GO) nanocomposite was synthesized using in-situ polymerization and direct blending of PDGP and graphene oxide nanoparticles. The products were named nanocomposite 1 and nanocomposite 2, respectively. The prepared nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy. Surface morphology and structure of nanocomposites were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The performance of the synthesized nanocomposites in removing Pb (II) and methylene blue dye from aqueous solutions was evaluated. The effect of pH, adsorbent dosage, contact time and contaminant concentration on Pb (II) and methylene blue uptake capacity was studied. On the other hand, the percentage removal of Pb (II) metal ion by nanocomposite 2 (96%) was higher than that of nanocomposite 1 (88%). The optimum condition for effective removal of methylene blue dye by nanocomposite 1 (94%) and nanocomposite 2 (98%) could be obtained at pH 8, nanocomposite dosage of 100 mg, contact time of 60 min and methylene blue concentration of 80 mg/L. Langmuir and Freundlich isotherm models, pseudo-first-order and pseudo-second-order kinetics equations and thermodynamic models were used to determine the mechanism of Pb (II) and methylene blue adsorption on the nanocomposite 2. The results showed that the Langmuir isotherm, pseudo-first-order kinetic and spontaneous adsorption were suitable models for Pb (II) sorption on nanocomposite 2, while the Freundlich isotherm, pseudo-second-order kinetic and spontaneous adsorption were suitable models for methylene blue dye removal. Therefore, the PDGP/GO nanocomposite prepared by direct blending could be considered as a promising adsorbent for Pb (II) and methylene blue removal from aqueous solutions.