“…excess oil was removed by placing the oil-EG mixture on a filter paper for 24 h. After that the oil saturated EG was picked up and weighed to determine the amount of adsorbed oil and calculate the specific sorption. This technique has been used in previous studies for measuring heavy oil sorption of EG, however without investigating the pore size distribution of EG [16, 32]. Fig.…”
Section: Methodsmentioning
confidence: 99%
“…Teplykh et al [4] determined the crystal structure of the main phase of EG samples prepared by rapid thermal decomposition of intercalation compounds of graphite aminofluoride, oxidized graphite and graphite fluoride using neutron diffraction and X-ray diffraction analysis. Hristea et al [16] prepared EG by suspending graphite in a mixture of H 2 SO 4 and HNO 3 . Then oxidizing agents such as KMnO 4 or FeCl 3 were added.…”
The pore structure of expanded graphite (EG) including pore volume, pore size distribution and surface area is investigated by mercury porosimetry, nitrogen adsorption and SEM. Also, the diffusion of silicone oil molecules as macromolecules with different molecular weights into EG pores is studied. Various EG samples were prepared by the sudden heating of graphite intercalated compound (GIC) with varying particle size of 35, 50, 80 and 200 meshes in an electrical furnace at temperatures of 700, 800 and 900 °C. The EGs were characterized by FTIR to evaluate the presence of functional groups. It was found that the exfoliation process has not significantly introduced oxygen functional groups such as epoxy and carboxyl groups to the EG structure. Therefore the chemical structure of the EG is very close to pristine graphite. The mercury porosimetry results showed a broad range of total pore area from 5 to 31 m2/g for the EGs. The particle size of GIC and exfoliation temperature showed strong effects on the pore size of EG. The mercury intrusion porosimetry and nitrogen adsorption isotherms revealed that μm-pores are dominant as compared with nm-pores in all EG samples. The diffusion of silicone oils as macromolecular guests with three different viscosities was experimentally studied to analyze the diffusion facts of EG as the host. It was observed that as the exfoliation temperature decreases, the sorption capacity decreases; and EG samples prepared from the GICs with smaller particle size have lower sorption capacity. Sorption experiments also showed that the whole pore volume of EG is not filled with silicone oil leading to this fact that EG includes relatively closed pores. A new model was suggested for the sorption capacity of EG as a function of the pore area of EG and the square root of molecular weight of silicone oil.
“…excess oil was removed by placing the oil-EG mixture on a filter paper for 24 h. After that the oil saturated EG was picked up and weighed to determine the amount of adsorbed oil and calculate the specific sorption. This technique has been used in previous studies for measuring heavy oil sorption of EG, however without investigating the pore size distribution of EG [16, 32]. Fig.…”
Section: Methodsmentioning
confidence: 99%
“…Teplykh et al [4] determined the crystal structure of the main phase of EG samples prepared by rapid thermal decomposition of intercalation compounds of graphite aminofluoride, oxidized graphite and graphite fluoride using neutron diffraction and X-ray diffraction analysis. Hristea et al [16] prepared EG by suspending graphite in a mixture of H 2 SO 4 and HNO 3 . Then oxidizing agents such as KMnO 4 or FeCl 3 were added.…”
The pore structure of expanded graphite (EG) including pore volume, pore size distribution and surface area is investigated by mercury porosimetry, nitrogen adsorption and SEM. Also, the diffusion of silicone oil molecules as macromolecules with different molecular weights into EG pores is studied. Various EG samples were prepared by the sudden heating of graphite intercalated compound (GIC) with varying particle size of 35, 50, 80 and 200 meshes in an electrical furnace at temperatures of 700, 800 and 900 °C. The EGs were characterized by FTIR to evaluate the presence of functional groups. It was found that the exfoliation process has not significantly introduced oxygen functional groups such as epoxy and carboxyl groups to the EG structure. Therefore the chemical structure of the EG is very close to pristine graphite. The mercury porosimetry results showed a broad range of total pore area from 5 to 31 m2/g for the EGs. The particle size of GIC and exfoliation temperature showed strong effects on the pore size of EG. The mercury intrusion porosimetry and nitrogen adsorption isotherms revealed that μm-pores are dominant as compared with nm-pores in all EG samples. The diffusion of silicone oils as macromolecular guests with three different viscosities was experimentally studied to analyze the diffusion facts of EG as the host. It was observed that as the exfoliation temperature decreases, the sorption capacity decreases; and EG samples prepared from the GICs with smaller particle size have lower sorption capacity. Sorption experiments also showed that the whole pore volume of EG is not filled with silicone oil leading to this fact that EG includes relatively closed pores. A new model was suggested for the sorption capacity of EG as a function of the pore area of EG and the square root of molecular weight of silicone oil.
“…4 showed, two main processes took place on the carbon-containing composite when the sample was heated; physically adsorbed water was removed below 423 K at first [29], followed by the combustion of carbon engendered from the carbonization accompanied with an obvious weight loss from 550 K to 950 K, including dehydroxylation of silanol group and residual coke combustion [29]. In general the combustion of amorphous carbon occurs between 573 K and 673 K whereas oxidation of graphite takes place at around 973 K [30,31]. Accordingly the carbon combusted in the TG-DSC test can be tentatively divided to amorphous carbon (573-673 K), a kind of graphite (908 K) and the intermediate between amorphous and graphite (673-900 K).…”
“…Due to its low density, high specific surface area and high expansion volume and wide pore size distribution typically ranging from 2 nm to 10 µm [6,7], EG exhibits an exceptional binding capacity for petroleum (83 g heavy oil g EG -1 [8]) and its constituents. Since its discovery in the late 18 th century, EG has been studied for the exfoliation process, its sorption capacity and surface modifications to improve the sorption of oil [9,10] and dissolved chemicals [11].…”
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