Papers by Keyword: Expanded Graphite (EG)

Abstract: In the present work, expanded graphite (EG) was prepared by microwave irradiation. Then, the expanded graphite/polyaniline (EG/PANi) composite was synthesized in the typical method. The samples of EG and EG/PANi were characterized by SEM and IR analysis techniques. Adsorption property of EG/PANi composite for removing the dye, reactive brilliant red K-2BP, from aqueous solution was investigated. The effects of initial dye concentration and contact time, pH, sorbent dosage on the adsorption process were studied. Experimental data were modelled by Langmuir and Freundlich isotherms. Langmuir isotherm model fitted well the equilibrium data for EG/PANi composite comparing to the Freundlich isotherm model. The uptake capacity of EG/PANi for K-2BP was found to be 1.03047 mg/g. The results indicated that EG/PANi composite is not an ideal sorbent used for reactive dye removal.

Abstract: The expanded graphite (EG) was prepared after microwave irradiation treatment of the expandable graphite in a domestic microwave oven at 1000 W for 60 s. The adsorption of methyl orange (MO) from aqueous solution onto EG was investigated at initial concentrations and contact time, different pH values, adsorbent dosage, temperatures for the removal of dye. The results confirmed that the adsorption isotherm data fitted to Langmuir isotherm with monolayer adsorption capacity of 13.37 mg/g. The results suggested that the EG would be an excellent adsorbent for the removal of MO by adsorption process.

Abstract: This paper deals with the synthesis and characterization of poly(ethylene glycol)-grafted expanded graphite (PEG-grafted EG) as a novel composite material. The PEG-grafted EG composite was prepared by grafting PEG in the EG layers using isophorone diisocyanate (IPDI) as coupling agent. The EG was prepared after microwave irradiation treatment from the expandable graphite, the obtained EG modified by an excess amount of IPDI. Modified expanded graphite (MEG) mixed in anhydrous N,N-dimethylformamide (DMF) and grafted PEG at low temperature atmosphere. The samples of EG and PEG-grafted EG composite was characterized by using scanning electron microscopy (SEM), infrared spectroscopy (IR) and thermogravimetric (TG) analysis technique.

Abstract: A kind of carbon nanotube/expanded graphite (EG/CNT) was used as counter electrodes for the DSSCs following five different weight ratios of 1:0, 1:1, 1:2, 2:1, and 0:1. The impedance spectra and J-V curves were recorded using the Zahner Zennium CIMPS system based on an IM6x electrochemical workstation. The dynamic parameters of the cells were discussed with the intensity-modulated photo current spectroscopy (IMPS) and the intensity modulated photo voltage spectroscopy (IMVS) using white light-emitting diode (75w/m², 604nm, LED) as the light source.

Abstract: We report an easy and scaleable approach to produce single and double layer graphene (Gr)-sheet from re-exfoliation of expanded graphite (EG) with large area. Transmission and scanning electron microscopic observations show that the Gr-sheets have an area of ~ (12 x 10) μm². Raman spectroscopy has confirmed the presence of single and double layer Gr-sheet with I_2D/I_G ratio as ~ 1.7. Scanning probe microscopy studies reveals that on re-exfoliation of EG, thickness of Gr-layer decreases from 6-7 nm to 0.8-1.1 nm. This infers that re-exfoliation overcomes the problem of insufficient oxidation or inadequate pressure buildup during heat treatment.

Abstract: The adsorption of p,p’-DDT onto expanded graphite (EG) in aqueous solutions was investigated under varying conditions of p,p’-DDT concentrations, adsorbent doses, pH, and contact time. The removal efficiency of p,p’-DDT from the aqueous solutions remained constant in a range of pH 2 to 10, and the thermodynamic data followed the type II adsorption isotherm characterized by a spontaneous process. At lower concentrations, adsorption equilibrium of p,p’-DDT onto EG was fitted to Freundlich isotherm. Dynamic modeling of the adsorption showed that the first order reversible kinetic model was held for the adsorption process within the range of experimental concentration. It was suggested that expanded graphite can be used for efficient removal of p,p’-DDT from water and wastewater.

Abstract: Polystyrene(PS)/Polystyrene-expanded graphite(EG)(PS/PSEG) composites were prepared by melt blending, using a variety of PSEG. The electrical and mechanical properties of the PS/PSEG were measured. Mechanical property measurements of composites indicated higher impact strength and lower tensile strength with increasing content of PSEG. Exfoliated graphite has seen a significant reduction for composites in electrical resistivity.

Abstract: A composite photo-catalyst of nano-TiO2 (TIO) grafted in the pores of expanded graphite (EG) was prepared by a process that included microwave irradiation method and hydrolysis method directly. Fourier transformation infrared spectroscope (FT-IR), Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to characterize the structure and the chemical structure of the photo-catalyst. The results indicate that expanded graphite had a unique net-like pores structure and nano TiO2 was loaded on EG to form EG/ TiO2 (EGTIO) composite photo-catalyst.

Abstract: A composite photocatalyst of needle nano-ZnO grafted in the pores of expanded graphite (EG) was prepared by a process of hydrolysis method directly, in which the expanded graphite was prepared by microwave irradiation. Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transformation infrared spectroscope (FT-IR) were used to characterize the structure and the chemical structure of the photo-catalyst. The results indicate that expanded graphite had a unique net-like pores structure and needle nano-ZnO was loaded on EG to form EG/ZnO composite photo-catalyst.

Abstract: Conductive fine flake expanded graphite/polyaniline composites was prepared by emulsion polymerization with sodium dodecyl benzene sulfonate(SDBS) as emulsifying agent, ammonium persulfate as initiator, hydrochloride and fine flakeexpanded graphite as dopants. Effects of hydrochloric acid, dopant, emulsifier and initiator to the conductivity has also been found through orthogonal experiment. The best condition, under which the conductivity is over 2.0S/cm, is 6% doped graphite, 6ml hydrochloric acid, 5.00g emulsifier and 3.25g initiator. It also demonstrates the improvement of the conductivity of polyaniline (PANI) via addition of graphite.