Reduced graphene oxide supported Fe/Ni bimetallic nanoparticles for the rapid adsorption and dechlorination of 2,4-dichlorophenol

Agglomeration and passivation of nanoscale zerovalent iron (nZVI) can result in significant decrease of reactivity with contaminants. In this paper, reduced graphene oxide supported Fe/Ni bimetallic composites (Fe/Ni@rGO) were synthesized. Electron microscopy characterization showed that the spherical Fe/Ni bimetallic nanoparticles with the size of 70-150 nm were successfully loaded on the graphene sheets and mainly distributed at the edges and folds of the graphene sheets. The agglomeration of nZVI decreased significantly and more active sites were exposed. The removal efficiency of 2,4-dichlorophenol by nZVI, reduced graphene oxide supported nZVI (Fe@rGO) composites and Fe/Ni@rGO composites were 14.4%, 71.8% and 95.0% within 180 min, respectively. The results showed that when the pH was 5-7 and humic acid concentration was 60 mg/L, the removal efficiency of 2,4-dichlorophenol was higher. According to the correlation coefficient R2, the removal of 2,4-dichlorophenol by Fe/Ni@rGO followed the pseudo second order model instead of the pseudo first order model. The anti-oxidation and cycle test showed that Fe/Ni@rGO composites had high stability and recycling value. The removal mechanism of 2,4-dichlorophenol by Fe/Ni@rGO composites was the synergistic effect of adsorption by rGO and dechlorination by Fe/Ni.

Automated summary

In this study, reduced graphene oxide supported Fe/Ni bimetallic composites were synthesized and successfully loaded on graphene sheets. The Fe/Ni@rGO composites showed decreased agglomeration of nZVI, exposed more active sites, and exhibited high removal efficiency for 2,4-dichlorophenol. The composites also demonstrated high stability and recycling value.