Biopreparation Of RGO And Effects Of RGO-based Materials On Nitrobenzene Bioreduction

Graphene is a novel two-dimensional carbon nanomaterial, which is composed of monolayer of carbon atoms. The preparation and application of graphene have become popular research topic due to its extraordinary electrical, mechanical and thermal properties. With the increase of its production and use, reduced graphene oxide (rGO)-based mateirals are inevitably released into natural environment, resulting in ecological risks. In recent years, although there have been many studies on the environmental behavior of rGO-based mateirals, including their transport through porous media and their effects on the transport and fate of pollutants, little was known about the interaction between rGO-based mateirals and microorganisms. In this study, the effects of quinone compounds on bioreduction of graphene oxide (GO) were investigated. In addition, the effects of different rGO-based materials on nitrobenzene reduction by Shewanella oneidensis MR-1 were also examined.The effects of anthraquinone-2-sulfonate (AQS), anthraquinone-2,6-disulfonate (AQDS), anthraquinone-2-carboxylate (AQC) and 5-hydroxy-1,4-naphthoquinone (JQ) on bioreduction of GO were investigated. The results showed that AQS, AQDS and JQ stimulated whereas AQC inhibited GO reduction by S. oneidensis MR-1.The inhibition effect of AQC could be attributed to its toxicity to cells. The resultant reduced graphene oxide (Bio-rGO) possessed peroxidase-like activity, which could catalyze the oxidation of 3,3’,5,5’-tetramethylbenzidine (TMB) by H2O2. The reaction followed Michaelis-Menten kinetics. The possible catalytic mechanism was that the presence of Bio-rGO facilitated electron transfer from TMB to H2O2 and thereby accelerated the oxidation of TMB by H2O2. A rapid colorimetric method for glucose detection based on the peroxidase-like activity of Bio-rGO was developed over a range of 1-120 μM with a detection limit of 1 μM. And good specificity was observed with the method.The effects of rGO, and rGO-based materials including nitrogen-doped rGO (N-rGO), Au nanoparticles decorated rGO (Au-rGO) and amino-formylimidazole modified rGO (imidazole-rGO) on bioreduction of nitrobenzene were studied. Different stimulating effects on bioreduction of nitrobenzene by S. oneidensis MR-1 were observed with the four rGO materials studied. The stimulating activity ranked in a descending order of N-rGO> rGO> Au-rGO> imidazole-rGO. It was found that specific surface area and electrical conductivity were the two main factors which influenced the stimulating effects of rGO-based materials.