Abstract:
Graphene oxide (GO), reduced graphene oxide (rGO) and hydrogen peroxide-modified reduced graphene oxide (rGO (H
2O
2)) were prepared and their effect on the reduction of Fe (III) in a coupled system of iron-reducing bacteria and iron oxides was studied. The formation of secondary minerals and the electron transfer processes in graphene were investigated. The kinetics of carbon tetrachloride degradation by iron-reducing bacteria and iron oxides mediated by graphene was determined, and the mechanism of carbon tetrachloride degradation by iron-reducing bacteria and iron oxides mediated by graphene was studied by electrochemistry. The results showed that the specific surface area of rGO was the largest, which facilitated the adsorption of iron oxides and organic compounds. Among the different graphenes, rGO and GO had the strongest and weakest electron transfer ability, respectively. H
2O
2 could reduce the quinone, semiquinone and other redox-active functional groups in graphene, thus compromising the electron transfer ability. All materials effectively assisted iron-reducing bacteria to reduce goethite, with rGO being the most effective on iron reduction of Shiva bacteria. The materials could also promote the degradation of carbon tetrachloride in a coupled system of iron oxides and iron-reducing bacteria, with rGO being the most effective. The mechanism of action was proposed to be the strong electron transfer ability of quinones and other functional groups on the surface of graphene, its larger specific surface area, and the abundance of adsorbed Fe (II) on the surface. In addition, the formation of secondary minerals with a strong reduction ability also contributes to the action.