Ultrasonic-assisted production of zero-valent iron-decorated graphene oxide/activated carbon nanocomposites: Chemical transformation and structural evolution

Highlights: • A nanocomposite was developed comprising GO and activated carbon supported nZVI. • nZVI size switched to • Sonication leads to the accommodation of more active carbon and nZVI between GO sheets. • Crystallinity of the nanocomposites under sonication was increased due to rapid nucleation. • VSM assay indicated that sonication did not change the magnetic characteristics. Nanotechnology has revolutionized many fields and produced nanostructures are promising materials for different industries. Nanoadsorbents as an emerging class of nanostructures can have potential applications for the separation and removal of both hazardous materials (such as heavy metals from water) and useful ingredients (such as vitamins and natural pigments from food wastes). The present study introduces a novel nanoadsorbent based on the ternary combination of zero valent iron/graphene oxide/active carbon (nZVI/GO-AC) with different formulations and using ultrasonication for improved physical properties. The nanocomposites were prepared by sodium borohydride reduction of graphene oxide, active carbon and ferrous sulfate under a nitrogen atmosphere and ultrasonication. Characterization of the developed nanocomposites was done by instrumental techniques, such as FTIR, VSM, FE-SEM, XRD, EDS, AFM and Raman analysis. The results indicated that the size of particles was 50 nm in the blank sample; however, when GO entered the composition, the particle size switched to <10 nm (either with or without ultrasonication). Also, the crystallinity of the ultrasound-assisted prepared nanocomposites enhanced by rapid nucleation in this method. Interestingly, the nanocomposites were superparamagnetic at ambient temperature and were separated by an external magnetic field. Altogether, at lower concentrations of GO in comparison to active carbon, the space between the GO sheets was higher and thus, there was more space for the accommodation of nZVI, which raises the rate of adsorbance. The immobilization process of nZVI on the composite platform improves the stability of the nZVI, whereas graphene coupling accelerates the transfer of electrons in nZVI and hinders the surface passivation of nZVI, resulting in the adsorption of target compounds.