Papers by Keyword: Expanded Graphite (EG)

Abstract: This paper presents the experimental results given by the operation of a chemical sorption refrigeration system using Expanded Graphite/Activated Carbon/Lithium Chloride (AC/GE/LiCl)-Adsorbent (NH₃ in solution with a 25% concentration). Experimental protocol with the characteristics of the experimental rig developed, working pair specifications and the procedure that has developed in the process is described in detail. Results are presented for different behaviors of the system, where the desorption stage is driven by forced convection. Measurements of the thermal variables of the system show that the adsorption-desorption cycles in the test accomplished, with high and low-pressure zones clearly defined. The cooling effects for the pair material studied have the expected behavior for the mixture proposed.

Abstract: The powdered expanded graphite (EG) was used as a porous adsorbent for the removal of the cationic dye, methylene blue (MB), from aqueous solution. The dye adsorption experiments were carried out with the bath procedure. Adsorption isotherms at different temperatures were determined and modeled with Langmuir and Freundlich equations. Thermodynamic parameters were calculated and correlated with the adsorption behaviors. The effects of solution pH on the adsorption were also studied.

Abstract: Expanded graphite (EG) was prepared by microwave irradiation and evaluated as adsorbent for the removal of disperse blue 2BLN (DB) from aqueous solution by the batch adsorption technique under different conditions of initial pH value, adsorbent dosage, initial dye concentration and contact time. The experimental data were analyzed considering pseudo-first-order, pseudo-second-order and intra-particle diffusion approaches. The adsorption kinetics at room temperature could be expressed by the pseudo second order model very well. The results indicate that the adsorption rate is fast enough and more than eighty percent of the adsorbed DB can be removed in the first 15 min at room temperature, which makes the process practical for industrial application.

Abstract: FeCoNi-expanded graphite (EG) microwave absorption composites were prepared by electroless plating process. Nickel、nickel-cobalt alloy and nickel-cobalt-iron alloy were plated to the expanded graphite, and the elemental composition, structure, magnetic and microwave absorption of these composites were investigated with the use of scanning electron microscopy, X-ray diffraction, energy dispersive spectra, hysteresis loop and electromagnetic parameter analysis. The microwave absorption properties were measured in the frequency range of 2.0-18 GHz. The results show that EG is plated symmetrical magnetic metal or their alloy, it is about 70~150nm thick. The coatings deposited from an electroless bath have the transformation of amorphous phase to crystalline phase after heat treatment 1h at 400°C.The magnetism capability of these composites is enhanced compared with pure EG. The optimum matching is 3mm thick and the maximum reflection coefficient shifts to lower frequency with the increase of thickness. The absorption property of FeCoNi-EG composite after heat treatment 1h at 400°C is the best, and when it is 3mm thick, the maximum theoretical reflection loss is about -28.8dB (the matching frequency is 13.5GHz), and the absorption bandwidth below -10dB is 8GHz. The other adsorption bandwidth below -10dB for plating Ni, Ni-Co, Ni-Fe on the surface of EG were 4.2GHz, 5.2GHz and 6.5GHz, respectively.

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.

Abstract: A simple method was developed for the preparation of zinc oxide (ZnO) nanofibers grafted on the expanded graphite(EG) under routine conditions. The synthesized materials were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The results show that the ZnO nanofibers, with a diameter of 50-150 nm, were randomly deposited on the expanded graphite.

Abstract: A new method to improve the adsorption ability of expanded graphite (EG) was introduced in this paper. EG was modified by nano magnesium hydroxide. Modified expanded graphite (MEG) was characterized by SEM, XRD and FTIR. Then, the removal rate of Pb (Ⅱ) rose to 99% from 60.51% on MEG, and the removal rate of Cr (Ⅵ) could reach at 23.9% from 12.36%.

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.

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.

Abstract: A new material on adsorption of Pb(Ⅱ) was introduced in this paper. EG was modified by soaking in KOH. MEG (modified expanded graphite) was characterized by SEM, XRD and FTIR. The removal rate of Pb(Ⅱ) rose to 92.23% from 59.14% on MEG . And the adsorption quantity came up to 46.3869mg/g from 31.9662mg/g. All above shows that MEG has better adsorption performance.