Investagition On Graphene Oxide And Its Composites And Their Properties Of Catalytic Degradatuon Of Acid Orange â…¡

As an ideal two-dimensional nano-material, graphene has become a significant direction in composite research due to its outstanding physical and chemical quality. The current paper investigated the removal of the azo dye acid Orange Ⅱ from water using CO3O4/GO/PMS catalytic oxidation system. Results show that the catalytic activity of Co3O4/mGO composites was related to the oxidation degree of graphite oxide. The details of research are as follows:(1) Preparation and characterization of graphene oxide with different oxidation degreeA series graphene oxide (including mGO-1, mGO-2and mGO-3) were prepared through improved Hummers method. Different oxidation degree of graphene oxide materials were obtained by adjusting the quantity of oxidant. Materials was characterized for X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman. The results suggest that graphite is oxidized to graphite intercalation compounds with various oxygen-bearing functional groups such as C-OH, COOH and C-O-C, etc. When the amount of oxidant is low, the crystal layers of graphite could not be intercalated and oxidized completely. Part of the structure for as-obtained products remains the periodic repetition as in graphite along the c-axis direction. With increasing the amount of oxidant, the graphite diffraction peak of products disappears gradually in XRD patterns. The content of oxygen-containing groups in as-obtained products obviously increases with increasing the amount of oxidant, and the hydrophilicity of products is improved. The curve fitting of FTIR data for graphene oxide samples showed the absorption peak which caused by C=C gradually disappeared. With the increasing in amount of oxidant, the integral ratio of intensity between D and G bands also increases indicating the decrease in average size of sp2graphitic domains in products.(2) Preparation and related study of the CoaCVmGO catalysts Using grapheme oxide as the presoma, CO3O4mGO (including Co3O4/mGO-1, Co3O4/mGO-2, and Co3O4/mGO-3) materials were synthesized by a one-pot solvothermal method in1-hexanol solvent. Then the composites were used to degrade AO7under the same experimental conditions. Results showed that Co304/mGO-3had best degradation efficiency of AO7and the removal rate was above90%in about8minutes. The composites were characterized with XRD, FTIR, Raman, XPS and TEM. The results indicated that the structure transformation of graphite into graphite oxide and the shaping of multi-model active sites were associated with the high performance. The degradation efficiency of Orange II in water by using Co304/GO composites as catalysts follows the order C03O4-3/GO＞C03O4-2/GO> Co3O4-1/GO＞Co3O4-4/GO＞Co3O4-5/GO. Further increasing the Co3O4loading results in a significant decrease of degradation activity. Besides, the formation of Co-OH complexes at the surface of Co3O4/mGO nanoparticles which due to the presence of hydroxyl groups decorated on the surface of carbon sheets and the surface bound water were proposed to facilitate the heterogeneous PMS activation.(3) Research on C03O4/N-GO/PMS catalytic systemCo3O4/N-GO composite was prepared by hydrothermal method. Results of AO7degradation experiment showed that the performance of catalyst Co3O4/N-GO was better than the Co3O4/mGO-3. This indicated N-doping of GO may be afford stronger coupling between Co and GO in Co3O4/N-GO. N-groups on GO serves as favorable nucleation and anchor sites for Co3O4nanocrystals because of the coordination with Co cations. Experimental results of the influence of inorganic salt ions are as followings:Cl" and NO3" had inhibitory effect on catalytic degradation while H2PO4" played a certain promote degradation role. Effect of HCO3" was positive at first but negative when at a high concentration. After three rounds of regeneration of the catalyst, the reaction could still finish within40min because of the stable performance of the catalyst, and the concentration of Co2+leached from the solution was still very low, it showed that the Co2O3from Co3O4determines the degradation rate instead of Co2+.