Preparation of Fe3O4-rGO via a covalent chemical combination method and its catalytic performance on p-NP bioreduction

Magnetic amino-reduced graphene oxide was successfully fabricated via a covalent chemical combination method. Fe3O4 was first reacted with polyacrylic acid (Fe3O4-COOH) and then reacted with diethylenetriamine; finally, the amino modified Fe3O4 (Fe3O4-NH2) was introduced as magnetic carrier and reductant to reduce graphene oxide to obtain Fe3O4-rGO. SEM, AFM, FTIR, XRD and XPS analyses were performed to analyze the synthesized materials. The catalytic performance of Fe3O4-rGO was investigated through the bioreduction of p-nitrophenol (p-NP) in the presence of Shewanella sp. CNZ-1. The results showed that p-NP bioreduction could be enhanced in a dose-dependent manner of Fe3O4-rGO. The p-NP reduction rate could achieve 0.92 mmol/(d gcell) in the presence of 25 mg/L Fe3O4-rGO, which was approximately 4.18-fold higher than that lacking Fe3O4-rGO. In addition, the experimental kinetic data of Fe3O4-rGO mediated P-NP bio-reduction fit well with the pseudo-first-order model (R2 > 0.96). These findings indicate that Fe3O4-rGO could be used in designing a bioreactor for enhancing the treatment of p-NP containing wastewater.