A novel poly(m-phenylenediamine)/reduced graphene oxide/nickel ferrite magnetic adsorbent with excellent removal ability of dyes and Cr(VI)

A novel poly(m-phenylenediamine)/reduced graphene oxide/nickle ferrite (PmPD/rGO/NFO) nanocomposite was synthesized by a facile hydrothermal method and in situ oxidative polymerization. The structure, morphology and magnetic properties were characterized by XRD, TEM, SEM, Raman and VSM. The results confirm the formation of PmPD/rGO/NFO nanocomposite. The adsorption properties of NFO, rGO/NFO, PmPD/NFO and PmPD/rGO/NFO for Congo Red (CR), methyl orange (MO), methyl blue (MB) and toxic heavy metal ion Cr(VI) were evaluated. Herein, the PmPD/rGO/NFO composite shows highest adsorption capacity for the above contaminants, which indicates that the combined introduction of rGO and PmPD greatly enhances the adsorption performance for dyes and metal ions. Notably, compared with the adsorption capacity of NFO, that of the PmPD/rGO/NFO nearly increases 11-fold, 6-fold, 2-fold and 4-fold for MB, MO, CR and Cr(VI) ion, respectively. The highest adsorption for Cr(VI) reaches 502.5 mg/g at pH = 3. The kinetic and isothermal studies suggest that the adsorption process can be best described by pseudo-second-order kinetic model and Langmuir model, respectively. The corresponding adsorption mechanism is presented. Owing to the easy magnetic separation and high adsorption capacity, the PmPD/rGO/NFO nanocomposites can be considered as a promising and excellent adsorbent for the simultaneous removal of dyes and Cr(VI) ion from wastewater. (C) 2017 Elsevier B.V. All rights reserved.