Papers by Keyword: Expanded Graphite (EG)

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Authors: S.R. Dhakate, N. Chauhan, S. Sharma, R.B. Mathur
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 I2D/IG 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.
1435
Authors: You Ya Zhou, Zeng Guang Yan, Kinam Kim
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.
1653
Authors: Ying Hua Zhao, Jin Hui Dong, Ying Chen Zhang, Min Cong Zhu, Deng Xin Li
Abstract: Expanded graphite (EG) was prepared by microwave irradiation at 1000 w for 60 s. It is a novel adsorbent for Pb (Ⅱ) adsorption. This paper aims to investigate the effect of the adsorption of EG. The adsorption behavior of Pb (Ⅱ) from aqueous solution onto EG was investigated with variety of parameters such as pH, adsorbents dosage, initial Pb (Ⅱ) concentration, contact time and temperature. On conditions that the pH=6.04,the dosage of adsorbent was 0.075g, the concentration of Pb(Ⅱ) was 100mg/L and the temperature was 15°C, the maximum removal rate could reach at 86.55% .The results showed that the EG was an efficient and novel adsorbent for the removal of lead from aqueous solution. The microstructures of the resultant expanded graphite were observed by scanning electron micrographs.
55
Authors: Ming Yang, Ying Hua Zhao, Ying Chen Zhang, Deng Xin Li
Abstract: Expanded graphite (EG) was prepared by microwave irradiation at 1000 w for 60 s. It is a novel adsorbent for Sn (Ⅱ) adsorption. This paper aims to investigate the effect of the adsorption of EG. The adsorption behavior of Sn (Ⅱ) from aqueous solution onto EG was investigated with variety of parameters such as pH, adsorbents dosage, initial Sn (Ⅱ) concentration, contact time and temperature. On conditions that the pH was 2.5, the dosage of adsorbent was 0.02 g, the concentration of Sn (Ⅱ) was 200 mg/L and the temperature was 15°C, the maximum removal rate can reach to 98.32%, and the adsorption quantity can reach to 245.7985 mg•g-1. The results showed that the EG was an efficient and novel adsorbent for the removal of stannum from aqueous solution.
89
Authors: Cheng Jin, Jin Hui Dong, Deng Xin Li, Min Cong Zhu, Ying Chen Zhang
Abstract: The expanded graphite coated with different portions of Fe3O4 nanoparticles (EG/ Fe3O4) were synthesized by a simple hydrothermal reaction and the composite was characterized by scanning electron micrograph (SEM), X-ray diffraction (XRD) and infrared spectroscopy (IR). The catalytic performance of the composite was studied through the degradation of methylene blue. The results indicated that a complete and uniform Fe3O4 nanoparticles coating on expanded graphite could be obtained under routine pressure and temperature and the optimum content of Fe3O4 in the composite was 6wt% in the experiment of catalytic degradation of methylene blue.
554
Authors: Kyung Seok Oh, S.I. Heo, J.C. Yun, Kyung Seop Han
Abstract: Conductive polymer composites (CPCs) consisting of expanded graphite (EG), flake-type graphite (FG) and thermalsetting resin were fabricated by means of a preform molding technique. Conductive fillers, EG and FG, were mechanically mixed with the phenol resin to provide an electrical property to composites. The filler loadings were fixed at 75wt.% to obtain a high electrical conductivity. The mechanical and electrical properties of CPCs were optimized according to the weight ratio and the particle size of FG. As the weight ratio increased, the flexural strength increased, however, the electrical conductivity decreased for both cases of CPCs using different sizes of FG. The particle size was an important parameter to change the mechanical and electrical behaviors. The flexural strength was sensitive to the particle size due to the different level of densification. The electrical conductivity also showed size-dependent behavior because of the different contribution to the conductive networking.
515
Authors: Min Cong Zhu, En Qiang Wang, Ying Chen Zhang, Deng Xin Li
Abstract: Expanded graphite (EG) was prepared by microwave irradiation at 1000W for 60s. The growth of coupled ZnO/TiO2 nanonods in the pores of EG by using hydrolysis method without harsh conditions was investigated and their microstructure was studied by scanning electron microscopy (SEM). Results show that pores of EG, which can load catalytic nanoparticles, is the physical base for growth of catalytic nanorods. The active edges of graphene of freshly EG is a key factor for the growth of coupled ZnO/TiO2 nanorods under non-catalytic and normal temperature and pressure conditions.
268
Authors: Xia Li, Yan Shuang Wei, Qian Qian Jin, Tie Zhen Ren
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.
1246
Authors: Ying Chen Zhang, Hong Yan Wu, Min Cong Zhu, Song Jian Zhao, Deng Xin Li
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.
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