Fabrication Of Graphene/Transition Metal Oxides And Its Properties Studies For Adsorption And Photocatalytic

With the rapid development of economy, environment problem, ecosystem and human health become increasingly serious due to human unscrupulous exploitment and the excessive discharge of industrial waste water. During those problems, the greatest harm is the serious groundwater pollution that has been caused by plenty emission of industrial wastewater. If not promptly and effectively remove those toxic contaminants, they will directly threaten human survival. Therefore, it is urgent to open the inexhaustible energy source and create permanent blue sky and clean water as a starting point. In this thesis, novel graphene-metal oxide nanocomposite materials were synthesized and their adsorption performances toward heavy metal ions and photocatalysis performances toward organic dyes were investigated. The details are summarized as follows:1. Highly porous, nanostructured composite adsorbent of reduced graphene oxides/Mn3O4(RGO/Mn3O4) was firstly fabricated with graphene oxide as substrates by a facile method of a combination of reflux condensation and solvothermal reaction and systemically characterized in infrared spectroscopy(FT-IR), X-ray diffraction(XRD), scanning electron microscopy(SEM), EDS, SEM-Maping, transmission electron microscopy(TEM), specific surface area(BET) and X-ray photoelectron spectroscopy(XPS). The results show that the RGO/Mn3O4 on heavy metal Sb(III) and Sb(V) with high stability and adsorption properties. Theoretical maximum adsorption capacity of RGO/Mn3O4 toward Sb(III) and Sb(V) are 151.84 and 105.50 mg/g, respectively, modeled by Langmuir isotherm. Kinetics studies show that the adsorption process obeys a pseudo-second-order kinetic model with high correlation coefficient(R2=0.9926 and 0.9969). It shows that the adsorption process is mainly chemisorptions. In addition, according to the form of Sb existing in water under different p H conditions and the results of Zeta-potentia, we well explained why RGO/Mn3O4 showed the maximum adsorption capacity with pH of 6. Finally, the residual Sb(III) and Sb(V) concentrations in the tap wate were 3.88 and 4.82 μg/L respectively, which had been detected by the actual simulation. The detection limit of Sb(III) and Sb(V) in test was lower than the corresponding criteria(6 μg/L) of the United States Environmental Protection Agency(USEPA). It indicates that the target products has a excellent adsorption performance, which is a good reference for the treatment of environmental pollution.2. Firstly, the precursor Mn3O4 was obtained through refluxing ethanol-water mixed solvent. Then, the graphene oxide as the substrate material was selected. Finally, the G-Mn3O4/MnCO3 of the different phases through changing pH of the solution was synthesized. The characterization of G-Mn3O4/MnCO3 were obtained and analyzed by FT-IR, XRD, SEM, TEM, BET and XPS. The changing of solution pH resulted in G-Mn3O4 and G-MnCO3 in structure-activity relationship reaching the best ratio of the heterostructure. Under the light irradiation, the photocatalytic behavior of composite photocatalyst on degradation of methyl blue organic pollutants was assessed. The result shows that, 5.5G-Mn3O4/MnCO3 has high photocatalytic performance and furtherly by fluorescence technology proved that the hydroxyl radical is the main active substances of photocatalytic. It is a theoretical basis that provided for the formation mechanism and photocatalytic enhancement mechanism of ternary composite photocatalyst.