Study On The Preparation And Application Of Micrometer/Nanometer Composite Materials

The development of new micro/nano composite materials and its application as adsorbent is of great significance. Graphene (G) is a novel micrometer/nanometer carbon material composed of a single atomic layer of sp2-hybridized carbon atoms. Owing to the large surface area, excellent electrical conductivity, thermal and mechanical properties, graphene has shown potential applications in sensors, supercapacitors, composite materials and drug delivery. As the graphene material has high specific surface area, it is expected to be applied as excellent adsorbent material. However, the strong hydrophobicity, aggregation between the sheets and less surface functional groups remain challenges in its application. Consequently, modification of graphene to prepare graphene micrometer/nanometer composites with hydrophilicity and functional group is of significant importance to explore the application as adsorbents. Owing to superparamagnetic properties, the magnetic nanocomposite materials have attracted tremendous interests in recent years. For the preparation of magnetic materials, magnetic Fe3O4 nanoparticles can serve as the core and the porous carbon materials with high specific surface area and available pore size serve as the shell. In this dissertation, we study on the preparation and application of two kind of adsorbent materials. The detailed results were summarized as follows:(1) A graphene-based adsorption materials were prepared and its application for the adsorption of Cu(II) ions were investigated. The single-layer graphene was prepared by the reduction of graphene oxide (GO). Then polydopamine (pDA) served as the linker to modify graphene via π-π stacking, which endowed graphene with good hydrophilicity. It was noting that G/pDA has the strong chemical stability in acid and alkaline conditions. Morever, pDA can serve as the linker to covalently immobilize the chelating compound of 3-mercaptopropionate acid (MPA) molecules to prepare G/pDA/MPA composite for the removal of Cu(Ⅱ). The synthesis of G/pDA/MPA composite materials were optimized. The adsorption conditions for Cu(II) were investigated. Results showed that the suitable pH for Cu(II) removal was about 7.0, and the foreign ion did not affect the adsorption performance. The adsorption of Cu(II) onto G/pDA/MPA increased sharply within 30 min and obtained equilibrium gradually. The Cu(Ⅱ) adsorption followed the Freundlich model. The maximum adsorption capacity for Cu(Ⅱ) was 1292.0 mg/g.(2) Magnetic porous carbon material was prepared and its adsorption to the organic pollutants methylene blue (MB) was investigated. The superparamagnetic property of mesoporous Fe3O4 was firstly preparaed via solution-thermal method. Fe3O4@SiO2 magnetic nanocomposites were synthesized by reacting Fe3O4 with tetraethylorthosilicate via sol-gel method. After carbonization of glucose by hydrothermal method, the core-shell magnetic nanocomposites were chemically activated with ZnCl2 to obtained porous carbon material (Fe3O4@SiO2@PC). The structural, surface, and magnetic characteristics of the material were investigated by Scanning electron microscope (SEM), Transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier Transform infrared spectroscopy (FTER.) and N2 adsorption-desorption measurement. The influence of the quality of ZnCl2/magnetic materials was studied by the property of the prepared materials. And adsorption equilibrium and kinetics were studied in a batch adsoption. Results showed that Fe3O4@SiO2@PC magnetic materials have a high specific surface area of 1730.2 m2g-1. And the saturation magnetization value was measured to be 16.7 emu/g, which was separated in 4 min by a magnet. And the adsorption of MB onto Fe3O4@SiO2@PC increased sharply within 40 min and obtained equilibrium gradually. The maximum adsorption capacity for MB was up to 1316.5 mg/g with a Langmuir adsorption equilibrium. Moreover, the magnetic Fe3O4@SiO2@PC could be easily separated and reused.