Facile synthesis of FeO anchored polyaniline intercalated graphene oxide as an effective adsorbent for the removal of hexavalent chromium and phosphate ions.

Adsorption media of hybrid composites is a promising candidate to eliminate the toxic contaminants from an aqueous environment, and good regeneration ability has received considerable interest to be utilized in water and wastewater treatment. Herein, we synthesized FeO anchored polyaniline intercalated graphene oxide (FeOx%-PANI@GO, where x = 10, 20 and 50% of FeO particles) hybrid composites by co-precipitation and modified Hummers' method, followed by in-situ polymerization. The as-synthesized FeOx%-PANI@GO acts as a potential host in welcoming the guest ions such as anionic contaminants with different interactions in this work. Besides, the advantages of easy separation by the external magnetic field, the FeOx%-PANI@GO hybrid composite also achieve a great adsorption efficiency of 143.54 and 135.67 mg/g for Cr(VI) and phosphate ions, respectively, than the other adsorbents reported in the literature. The as-synthesized adsorbents were characterized by different analytical techniques and influencing parameters such as contact time, co-existing anions, solution pH, adsorption isotherms, and kinetics were studied in detail. The adsorption system of FeO50%-PANI@GO hybrid composite follows the Langmuir isotherm and pseudo-second-order kinetic model for the elimination of Cr(VI) and phosphate ions from aqueous solutions. The feasible removal mechanism of Cr(VI) and phosphate ions was explored by FTIR and XPS techniques for anionic pollutants. Moreover, the selectivity and recyclability tests showed that the FeO50%-PANI@GO hybrid composites demonstrated a high adsorption capacity towards the anionic ions from the aqueous environment. Therefore, the present investigation suggested that the FeO50%-PANI@GO hybrid composites is an effective adsorbent for the elimination of Cr(VI) and phosphate ions from wastewater.