Preparation Of Graphene Composites And Their Applications In The Treatment Of Dye Wastewater

With the treatment of dye wastewater becoming a difficult task facing the world, it is extremely urgent to look for green energy saving ways and develop novel efficient materials to deal with the problem. Graphene now has presented excellent adsorption ability and a great potential applied value in the treatment of dye wastewater due to its huge surface area and numerous surface oxygenic functional groups. However, the agglomeration of graphene is inevitable, which results in lower adsorption ability and efficiency and confines its practical appliance in a certain extent.When composited with other materials, the graphene can be weakly agglomerated and even makes the composites more functional. Combing with zero valent Fe/Ni particles, the graphene-based composites not only have the dual function of adsorption and reductive degradation but also can be environmentally friendly, which has shown outstanding treatment results for certain dyes. The presence of mesoporous can prevent aggregation between graphene layers, thus significantly improving the graphene adsorption rate of dyes. The combination of graphene and magnesium hydrate could enhance the adsorption capacity, and the addition of magnetic Fe3O4 particles also made it possible to separate the solution and adsorbent.1. Preparation of graphene/bimetal composites materials. The solution of FeCl3 and NiCl2·6H2O was mixed with oxide graphene and stirred for 12 h, the mixture was then reduced completely by NaBH4 under nitrogen at room temperature to form graphene/bimetal composites which was exploited for the decoloration of crystal violet. XRD and FT-IR was used to analyze the phase and structure. After inspected by SEM and TEM, the results indicated that the bimetal particles were dispersed well on the graphene layers. Graphene and as-synthesized material’s experimental parameters such as dye solution pH, material amount, temperature and initial concentration of solution have been investigated by UV-spectrophotometer, respectively. The data showed that graphene belonged to the pseudo-second-order kinetic model and Langmuir isotherm model while the reductive degradation of Fe/Ni particles seemed to be consistent with first-order kinetic model. It was believed that the composites was better in degradation of dye than graphene.2. Synthesis of graphene/nano mesoporous silica composites. The composites were prepared using CTAB as template, TEOS and oxide graphene as silica source and precursor respectively. All of the materials were stirred at pH 8.5 and 20℃ to obtain GO/SiO2 composites after subsequent processing, and then obtain the target composite by thermal reduction reaction. The mesoporous silica with the same size evenly distributed on the graphene surface by the characterization of SEM and TEM. UV-spectrophotometer was used to scope the content of crystal violet to get the effects of experimental parameters including dye solution pH, material amount, temperature and initial concentration. It was believed that the pseudo-second-order kinetic model and Langmuir isotherm model were likely to be the best description to fit the data and the adsorption of dye was an endothermic processes according to the thermodynamic parameter.3. Synthesis of magnetic graphene/magnesium hydrate composites. FeCl3·6H2O and MgCl2·6H2O were mixed with oxide graphene which has been ultrasounded by ethylene glycol, the mixture was then added with NaOH to obtain the corresponding metal hydroxide and finally reduced to magnetic graphene/Mg(OH)2 by hydrothermal method at 180 ℃. XRD and FT-IR were used to analyze the phase and structure of the composites. After inspected by TEM, the results indicated that the Mg(OH)2 particles with a diameter of 3 nm dispersed on the graphene layers. UV-spectrophotometer was used to scope the content of crystal violet to get the effects of experimental parameters including dye...