Preparation and Microstructure of Two Kinds of Exfoliated Graphite

2013 ◽  
Vol 706-708 ◽  
pp. 211-214
Author(s):  
Ji Jin Zhao ◽  
Xiao Xia Li ◽  
Yu Xiang Guo ◽  
Tong Sun ◽  
Sen Ma
Keyword(s):  
Potassium Permanganate ◽  
Volume Ratio ◽  
Graphite Powder ◽  
Exfoliated Graphite ◽  
Graphite Flake ◽  
Mass Ratio ◽  
Mixed Acid ◽  
Preparation Conditions ◽  
Orthogonal Experiments ◽  
Mass Volume

Two kinds of exfoliated graphite have been prepared from graphite flake and graphite powder, and their preparation conditions were respectively optimized by orthogonal experiments and parallel experiments. The effect of graphite size on the characteristics of exfoliated graphite was researched. The microstructure of two kinds of exfoliated graphite was measured by SEM. The results show that the optimal preparation conditions for exfoliated graphite flake are as following: the mass-volume ratio of graphite to mixed acid is 1: 4, the volume ratio of nitric acid to phosphoric acid is 1: 2, the mass ratio of graphite to potassium permanganate is 1: 0.1, and the reaction temperature is 25°C. For exfoliated graphite powder, the optimal mass ratio of graphite powder to potassium permanganate is 1: 0.22, and the consumption of oxidant for exfoliated graphite powder is more than that for exfoliated graphite flake. The longitudinal expansion of graphite flake is more apparent than that of graphite powder and leads to a worm-like fluffy rope.

Preparation and Microstructure of Exfoliated Graphite with Large Expanding Volume by Two-Step Intercalation

2014 ◽  
Vol 852 ◽  
pp. 101-105 ◽  
Author(s):  
Ji Jin Zhao ◽  
Xiao Xia Li ◽  
Yu Xiang Guo ◽  
De Yue Ma
Keyword(s):  
Acetic Acid ◽  
Nitric Acid ◽  
Phosphoric Acid ◽  
Potassium Permanganate ◽  
Reaction Temperature ◽  
Volume Ratio ◽  
Exfoliated Graphite ◽  
Mass Ratio ◽  
Preparation Conditions ◽  
Mass Volume

Exfoliated graphite with large expanding volume (EV) was prepared by two-step intercalation, in which the mixture of nitric acid and phosphoric acid, and that of nitric acid and acetic acid were employed as intercalating agent step by step, and potassium permanganate was used as oxidant. Its preparation conditions were optimized by orthogonal experiment and parallel experiment, and its microstructure was analyzed by scanning electron microscope. The results show that the optimal preparation conditions for the first step intercalation are as follows: the mass-volume ratio of natural graphite (NG) to mixed acid is 1: 4, the volume ratio of nitric acid to phosphoric acid is 1: 2, the mass ratio of NG to potassium permanganate is 1: 0.2, and the reaction temperature is 20~30°C for 40~60 minutes. Those for the second step intercalation are as follows: the mass-volume ratio of acidized graphite (AG) to acetic acid is 1: 5, the mass-volume ratio of AG to nitric acid is 1: 1.5, the mass ratio of AG to potassium permanganate is 1: 0.15, and the reaction temperature is 20~30°C for 40~60 minutes, the EV is 450ml/g under the conditions listed above. The interlayers of graphite are fully opened and become a worm-like fluffy rope.

Preparation of Sulfur-Free Exfoliated Graphite in the Graphite-HClO4-CH3COOH Systerms

2015 ◽  
Vol 1094 ◽  
pp. 61-67
Author(s):  
Guo Jiang Zhou ◽  
Xiao Tong Feng ◽  
Guang Chao Lv
Keyword(s):  
Reaction Temperature ◽  
Influence Factors ◽  
Reaction Medium ◽  
Volume Ratio ◽  
Chemical Oxidation ◽  
Raw Material ◽  
Exfoliated Graphite ◽  
Mixed Acid ◽  
Preparation Conditions ◽  
Orthogonal Experiments

The sulfur-free exfoliated graphite(EG) was prepared by chemical oxidation method using the mixture of HClO4 and CH3COOH as reaction medium, the 100 orders natural flake graphite(NG) as raw material, and KMnO4 as oxidant. The effects of influence factors on the exfoliation volume(EV) were analyzed by single factor experiments and orthogonal experiments, the structure of NG and EG were characterized by X-ray diffraction. Results show that the optimum preparation conditions were as follows: graphite(g): KMnO4(g): the mixed acid (mL) = 1:0.35:4, HClO4 (mL):CH3COOH (mL) = 3:1, reaction temperature at 35°C for 90 minutes, the maximum EV of up to 500mL/g. The influence factors are governed the descending order: the volume ratio of HClO4 :CH3COOH, reaction temperature, the dosage of mixed acid, the dosage of KMnO4, reaction time.

scholarly journals Synthesis and Characterization of Reduced Graphene Oxide (rGO) Started from Graphene Oxide (GO) Using the Tour Method with Different Parameters

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Adere Tarekegne Habte ◽  
Delele Worku Ayele
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Potassium Permanganate ◽  
Chemical Reduction ◽  
Volume Ratio ◽  
Graphite Powder ◽  
Green Approach ◽  
Synthesis Strategy ◽  
Reduced Graphene ◽  
Diffraction Patterns

A new approach to synthesize graphene is oxidizing graphite powder with a mixture of H2SO4/H3PO4 acids and potassium permanganate. Parameters such as reaction time, reaction temperature, and amount of concentration were varied to study the degree of oxidation of graphite to graphene oxide. Currently, an improved method for the preparation of graphene oxide was the most common one. A mixture of H2SO4/H3PO4 (9 : 1 volume ratio) instead of only H2SO4 resulted in increased hydrophilic and oxidized GO without the emission of toxic gas, which differs from the traditional Hummers’ method. The graphene oxide (GO) was converted to reduced graphene oxide (rGO) by chemical reduction using ascorbic acid as the reducing agent. The GO and rGO were characterized by UV-visible spectroscopy, FTIR spectroscopy, and X-ray diffraction patterns. The result showed that treating graphite powder with potassium permanganate (1 : 9) and a mixture of concentrated H2SO4/H3PO4 acids at 50°C for 12 hours resulted in a better oxidation degree. The designed synthesis strategy could be easily controlled and is an alternative green approach for the production of graphene oxide and reduced graphene oxide.

scholarly journals The Choice of the Optimal Number of Discs in an MR Clutch from the Viewpoint of Different Criteria and Constraints

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6888
Author(s):  
Krzysztof Kluszczyński ◽  
Zbigniew Pilch
Keyword(s):  
Comparative Study ◽  
Mass Production ◽  
Manufacturing Process ◽  
Volume Ratio ◽  
Optimal Number ◽  
View Point ◽  
Mass Ratio ◽  
Active Materials ◽  
Materials Used ◽  
Mass Volume

This paper focuses on magnetorheological clutches (MR clutches) with a disc structure that can be designed as one-disc or multi-disc clutches (number of discs: N = 1, N > 2). The main goal of the paper is to compare their overall dimensions (lengths and radii), masses, volumes, and characteristic factors—torque per mass ratio and torque per volume ratio for MR clutches that develop the same given clutching torque Tc but differ in the number of discs (it is assumed that the number of discs of the primary member varies from one to four). This analysis develops charts and guidelines that will allow designers to choose the appropriate number of discs from the view point of various criteria, and with various limitations regarding geometry, geometric proportions, mass, volume, or restrictions on the amount of active materials used in the manufacturing process. The limitations on the active materials used are of particular importance in the case of mass production. Our methodology uses a comparative study, which can also be used when comparing design solutions of other electromechanical converters.

Employing Exfoliated Graphite as Novel Support Material for Heterogeneous Model Catalysts

2019 ◽  
Author(s):  
Moritz Wolf ◽  
Nico Fischer ◽  
Michael Claeys
Keyword(s):  
Surface Area ◽  
Graphite Powder ◽  
Model Catalysts ◽  
Model Systems ◽  
Exfoliated Graphite ◽  
Support Material ◽  
Heterogeneous Model ◽  
Support Materials ◽  
Metal Support Interaction ◽  
Catalyst Systems

<p>The inert nature of graphitic samples allows for characterisation of rather isolated supported nanoparticles in model catalysts, as long as sufficiently large inter-particle distances are obtained. However, the low surface area of graphite and the little interaction with nanoparticles result in a challenging application of conventional preparation routes in practice. In the present study, a set of graphitic carbon materials was characterised in order to identify potential support materials for the preparation of model catalyst systems. Various sizes of well-defined Co<sub>3</sub>O<sub>4</sub> nanoparticles were synthesised separately and supported onto exfoliated graphite powder, that is graphite after solvent-assisted exfoliation <i>via</i> ultrasonication resulting in thinner flakes with increased specific surface area. The developed model catalysts are ideally suited for sintering studies of isolated nano-sized cobaltous particles as the graphitic support material does not provide distinct metal-support interaction. Furthermore, the differently sized cobaltous particles in the various model systems render possible studies on structural dependencies of activity, selectivity, and deactivation in cobalt oxide or cobalt catalysed reactions.</p>

scholarly journals Preparation of Sulfur-Free Exfoliated Graphite by a Two-Step Intercalation Process and Its Application for Adsorption of Oils

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Jun He ◽  
Laizhou Song ◽  
Hongxia Yang ◽  
Xiaohui Ren ◽  
Lifei Xing
Keyword(s):  
Crude Oil ◽  
Perchloric Acid ◽  
Weight Ratio ◽  
Intercalation Compound ◽  
Diesel Oil ◽  
Chemical Oxidation ◽  
Exfoliated Graphite ◽  
Bet Surface Area ◽  
Graphite Flake ◽  
Intercalation Process

The sulfur-free exfoliated graphite (EG) was prepared by a two-step chemical oxidation process, using natural flake graphite (NFG) as the precursor. The first chemical intercalation process was carried out at a temperature of 30°C for 50 min, with the optimum addition of NFG, potassium permanganate, and perchloric acid in a weight ratio of 1 : 0.4 : 10.56. Then, in the secondary intercalation step, dipotassium phosphate was employed as the intercalating agent to further increase the exfoliated volume (EV) of EG. NFG, graphite intercalation compound (GIC), and EG were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), BET surface area, and porosity analyzer. Also, the uptakes of crude oil, diesel oil, and gasoline by EG were determined. Results show that perchloric acid and hydrogen phosphate are validated to enter into the interlayer of graphite flake. The obtained EG possesses a large exfoliated volume (EV) and has an excellent affinity to oils; thus, the material has rapid adsorption rates and high adsorption capacities for crude oil, diesel oil, and gasoline.

PRESSURE, VOLUME, TEMPERATURE RELATIONS OF ETHYLENE IN THE CRITICAL REGION. I.

1939 ◽  
Vol 17b (7) ◽  
pp. 206-213 ◽  
Author(s):  
J. Dacey ◽  
R. McIntosh ◽  
O. Maass
Keyword(s):  
Experimental Error ◽  
Heterogeneous System ◽  
Constant Pressure ◽  
Volume Ratio ◽  
Time Lags ◽  
Compressed Liquid ◽  
Region I ◽  
Flat Portion ◽  
Liquid States ◽  
Mass Volume

Pressure isothermals of the system were determined both above and below the temperature of disappearance of the meniscus. Regions of constant pressure with changing volume were observed with all isothermals, in agreement with the prediction of Mayer and Harrison (2, 3). The complete envelope of this region above the critical temperature has not as yet been determined. The pressure of the heterogeneous system at 9.50 °C. was found to correspond within experimental error to the pressure of the flat portion of the homogeneous isothermal at the same temperature. The pressure of this heterogeneous system was found to be independent of the mass-volume ratio; this is in agreement with the experimental behaviour previously discovered by the authors (5) for such a system at 9.80 °C. Moreover, the pressure of the heterogeneous system was found to be identical with that of the system which had been heated at constant volume to a temperature at which the density difference in the tube is known to have been destroyed, and then cooled to the same temperature of 9.50 °C.The isothermal at 9.60 °C. was studied, and shown to be the equilibrium curve at that temperature. A hysteresis was observed on reversing the direction of measurement, i.e., from "vapour" to compressed "liquid". This hysteresis was found to be caused by the time lags which are observed in passing from the "vapour" region of an isothermal to regions of high density. Certain apparent discrepancies between the work of the present authors and that of Geddes and Maass have been observed and cannot as yet be explained.The phenomena observed are interpreted on the basis of a difference between the gaseous and liquid states of aggregation, with a structure assigned to the latter.

Application of Nanometer Metal Oxides in Infrared Ray Shielding Transparent Thin Film

2011 ◽  
Vol 474-476 ◽  
pp. 195-199 ◽  
Author(s):  
Ai Hong Guo ◽  
Xue Jiao Tang ◽  
Su Juan Zhang
Keyword(s):  
Thin Film ◽  
Metal Oxide ◽  
Metal Oxides ◽  
Sol Gel ◽  
Volume Ratio ◽  
Experimental Results ◽  
Mass Ratio ◽  
Gel Method ◽  
Water Based ◽  
Better Than

Water-based infrared ray shielding coating, that is, nanometer metal oxide is added to the water-based paint, which has anti-IR features without affecting the transparency of the paint. In this paper, the nanometer oxides are prepared by sol-gel method, added into polypropylene sour. In order to improve the infrared ray shielding of the thin film, two kinds of nanometer oxides are added into the polypropylene sour with different volume ratios, the shielding performance of the paint is studied. Experimental results show: in the 8000 ~ 4000cm-1 range, the transmittances of infrared ray is 30% to 75%; in 4000 ~ 400cm-1 range, transmittances decrease significantly; 3% ZnO, 3% Fe2O3, 3% Y2O3, 2% Al2O3 are the best mass ratio of every single nanometer oxide; the infrared shielding rate of Fe2O3 and Y2O3 mixture with the volume ratio of 1 to 4 is better than Fe2O3 and Y2O3 single.

P-238 Left Ventricular Mass volume Ratio and Hazard of Adverse Cardiovascular Events

2009 ◽  
Vol 4 ◽  
pp. S119
Author(s):  
Michael Chuang ◽  
Philimon Gona ◽  
Carol J. Salton ◽  
Christopher J. O'Donnell ◽  
Warren J. Manning
Keyword(s):  
Left Ventricular Mass ◽  
Cardiovascular Events ◽  
Volume Ratio ◽  
Left Ventricular ◽  
Ventricular Mass ◽  
Mass Volume
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