Environment friendly synthesis of magnetite–graphene composite for adsorption of toxic chromium (VI) ions from drinking water

Abstract

Magnetite graphene composite (MGC) was synthesized via environment friendly route via thermal reduction of graphene oxide to graphene in alkali solution at 90°C and in the absence of toxic hydrazine hydrate. X‐ray diffraction pattern of MGC shows formation of magnetite phase with crystallite size of 10 nm. TEM image of MGC shows formation of regularly distributed magnetite particles on graphene sheets and average particle size of 10 nm. HRTEM image shows formation of lattice fringes with inter‐planar distance 0.482 nm. AFM shows formation of uniform size particles and cross sectional analysis shows formation of ∼10 nm magnetite particles and 2‐nm‐thick graphene sheets. The presence of different functional groups in the graphene oxide and MGC were confirmed from FTIR and Raman spectrophotometer. The sorption performance of MGC for Cr (VI) was evaluated. The maximum sorption capacity for Cr (VI) on MGC was 5.5 mg g−1 (pH =6.6) which was much higher than that of Fe3O4 nanoparticles. The graphene sheets could not only prevent agglomeration of the Fe3O4 nanoparticles and enable a good dispersion of this oxide, but also substantially enhance the specific surface area of the composite. The MGC composite may be a promising sorption material for the separation and preconcentration of heavy metal ions from aqueous solutions in environmental pollution cleanup. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 700–705, 2016