Preparation And Properties Of Expanded Graphite, TiO₂and Composite Materials

Expanded graphite (EG) is a worm-like material with loose and porous structure. Ithas large specific surface area and high surface activity, showing a kind of good andenvironmental adsorbent in dyes and oils sewage treatment. Anatase-type TiO2has highphotocatalytic activity and stability in aqueous media, which can completely degrademany refractory organic pollutants into CO2, H2O and inorganic ions, and make it hasbroad application prospects in the field of photodegradation of water contaminants. TiO2isloaded into EG can get the TiO2/EG composites, it will combine the adsorption property ofEG with the photocatalytic property of TiO2, which show a new way of thinking and focusin sewage treatment.In this paper, EG was prepared by the chemical oxidation method, TiO2was preparedby the sol-gel method, and TiO2/EG composites was prepared by the precursor mixingmethod. The properties of samples were characterized by means of FE-SEM, TEM, XRD,FT-IR, N2physical adsorption measurements, TG-DTA, and UV-Vis. Meanwhile, theadsorption or photocatalytic properties of samples were investigated by methyl orange(MO) aqueous solution, rhodamine B (RhB) aqueous solution and oils as the probereaction. The main research results are as follows:Household microwave has the best effect in three expansion ways of householdmicrowave, microwave special equipment and muffle furnace, expanded volume of EGcan be up to365mL/g. EG with loose, porous and worm-like morphology, the pores ofEG samples can be divided into three levels from FE-SEM images, and it has nonpolarsurface. These make EG as an excellent material for absorbing dye molecules and oils inaqueous media. When the abundant third level pores, the fed-batch, the low concentrationof dye and the external force stirring, EG possess the optimal adsorption anddecolorization effect for dyes wastewater. With increasing of expanded volume and oilviscosity, the oil adsorption increases correspondingly.The transition from anatase TiO2to rutile TiO2occurs at calcination temperature500℃, the average grain sizeincreases as the calcination temperature increases.As-prepared TiO2have good photocatalytic property, the decolorization rate of the RhB aqueous solution is up to99.44%ater180min by UV irradiation, and the experimentalresult is better than80.65%of the commodity TiO2.TiO2/EG composites maintain the worm-like morphology of EG with the loose andporous structure. Anatase TiO2nano-flaky particles distribute on the surface and the innerwall of EG. The decolorization rate of RhB aqueous solution and MO aqueous solutioncan reach96.84%and84.71%, respectively. Photocatalytic degradation of crude oil isanalyzed by FT-IR and UV-Vis, the results are also show that TiO2/EG composites havegood adsorption property and photocatalytic property.