Facile adsorptive removal of dyes and heavy metals from wastewaters using magnetic nanocomposite of zinc ferrite@reduced graphene oxide

Graphene-based nanomaterials can be tailored as green and excellent adsorbents for wastewater treatment. Herein, reduced graphene oxide was synthesized by a modified Hummer's method and decorated with zinc ferrite nanoparticles for the efficient adsorptive removal of lead, and methylene blue dye from aqueous solutions. The characteristics of the nanocomposite adsorbent (ZnFe2O4@rGO, MrGO) were ascertained by various phys-icochemical tools including: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field Emission scanning electron microscopy with energy dispersive X-ray spectrometry (FESEM-EDX), X-ray photo-electron spectroscopy (XPS), Zeta potential, and Vibrating sample magnetometer (VSM) analysis. Various pa-rameters, influencing the adsorptive removal of pollutants, were thoroughly explored and optimized including the mass of adsorbent, initial concentration of adsorbate, and medium pH. The synthesized MrGO nano -adsorbent exhibited excellent adsorption capacities towards model pollutants of lead ions and methylene blue dye of 89.8 and 119.0 mg g(-1), respectively. A plausible mechanism of pollutants' removal on the synthesized nanocomposite was attributed mainly to the vacancy defects and oxygen bearing functional groups of the MrGO nanoparticles' surfaces. The adsorption isotherms conformed to the Langmuir, rather than the Freundlich, model and followed the PSO kinetic model suggesting a chemisorption process via pollutants monolayers on the MrGO nanoparticles' surfaces. The synthesized MrGO nanocomposite was excellently stable and reusable for five consecutive cycles; and therefore, it can be a promising adsorbent for the effective removal of pollutants of heavy metals and dyes for environmental remediation purposes.