AN ISOPIESTIC INVESTIGATION OF CHARCOAL ACTIVATION

1949 ◽  
Vol 27b (2) ◽  
pp. 101-115
Author(s):  
S. Barnartt ◽  
J. B. Ferguson
Keyword(s):  
Capillary Condensation ◽  
Relative Rate ◽  
Saturation Pressure ◽  
Isopiestic Method ◽  
Activation Process ◽  
Steam Activation ◽  
Sorption Data ◽  
Straight Lines ◽  
Low Pressures ◽  
Chemically Selective

The isopiestic method was used to study the sorption of carbon tetrachloride, water, methanol, and toluene by a series of charcoals representing the same coconut shell source at different stages of steam activation. The sorption of water by two charcoals of this series impregnated with benzoic acid was similarly investigated. The isopiestic charges of this activation series of charcoals were linearly related over wider pressure ranges than were those of unrelated charcoals. The activation process was found to be connected primarily with the principal pressure range over which single straight lines were obtained on plotting the isopiestic charges one against the other. The isopiestic data presented the following picture of charcoal activation. The activation process has created surfaces, probably of a heterogeneous character, which are active to all the four vapors studied. At any stage of activation these surfaces take up proportionate quantities, but not equal liquid volumes, of each sorbate at saturation pressure. The various types of surfaces increase in abundance with activation at the same relative rate, so that they are always present in the charcoal in the same relative proportions, up to a certain stage of activation. At this stage the production of the surfaces active at relatively low pressures begins to decline. This indicates that new pores are being created more slowly in comparison with the widening of existing pores. In addition to the active surfaces just described, the activation process produces some chemically selective centers which are active at minute relative pressures. The water sorption data discredit the theory of capillary condensation.

scholarly journals Optical Detection of Vapor Mixtures Using Structurally Colored Butterfly and Moth Wings

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3058 ◽  
Author(s):  
Gábor Piszter ◽  
Krisztián Kertész ◽  
Zsolt Bálint ◽  
László Péter Biró
Keyword(s):  
Capillary Condensation ◽  
Principal Component ◽  
Sensor Material ◽  
Conformal Change ◽  
Vapor Sensing ◽  
Optical Responses ◽  
Surrounding Atmosphere ◽  
Vapor Mixtures ◽  
Chemically Selective ◽  
Wing Scales

Photonic nanoarchitectures in the wing scales of butterflies and moths are capable of fast and chemically selective vapor sensing due to changing color when volatile vapors are introduced to the surrounding atmosphere. This process is based on the capillary condensation of the vapors, which results in the conformal change of the chitin-air nanoarchitectures and leads to a vapor-specific optical response. Here, we investigated the optical responses of the wing scales of several butterfly and moth species when mixtures of different volatile vapors were applied to the surrounding atmosphere. We found that the optical responses for the different vapor mixtures fell between the optical responses of the two pure solvents in all the investigated specimens. The detailed evaluation, using principal component analysis, showed that the butterfly-wing-based sensor material is capable of differentiating between vapor mixtures as the structural color response was found to be characteristic for each of them.

scholarly journals Preparation and characterization of activated carbon from bio-diesel by-products (Jatropha seedcake) by steam activation

2012 ◽  
Vol 47 (3) ◽  
pp. 257-264
Author(s):  
MS Islam ◽  
MA Rouf ◽  
S Fujimoto ◽  
T Minowa
Keyword(s):  
Activated Carbon ◽  
Structural Changes ◽  
Pyrolysis Temperature ◽  
Hold Time ◽  
Raw Material ◽  
Bet Surface Area ◽  
Activation Process ◽  
Steam Activation ◽  
Activation Temperature ◽  
Ft Ir

Activated carbon was prepared using bio-diesel waste (Jatropha seedcake) by conventional carbonization followed by steam activation process on a laboratory scale. Preliminary tests were conducted to investigate the influences of different operating parameters, such as initial material size, pyrolysis temperature and hold time on the properties of pyrolized chars. To determine the optimum conditions for producing activated carbon, the effect of activation temperature and activation time have been studied. The maximum BET surface area of 613.43 m2/g and highest methylene blue adsorption capacity of 8.27 mg/g was obtained at a pyrolysis temperature of 600°C for hold time 1.5 hr followed by steam activation at a temperature of 800°C for a hold time of 1 hr. The produced activated carbon was almost like ash at 900°C. FT-IR and TG/DTA have been done in order to understand the structural changes during the process. The waste material was a suitable raw material for the production of good quality activated carbon. DOI: http://dx.doi.org/10.3329/bjsir.v47i3.13056 Bangladesh J. Sci. Ind. Res. 47(3), 257-264, 2012

Preparation of activated carbon from needle coke via two-stage steam activation process

2019 ◽  
Vol 237 ◽  
pp. 22-25 ◽  
Author(s):  
Ui-Su Im ◽  
Jiyoung Kim ◽  
Seon Ho Lee ◽  
Song mi Lee ◽  
Byung-Rok Lee ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Activation Process ◽  
Needle Coke ◽  
Steam Activation ◽  
Two Stage

Zerfallszeiten von Molekülionen. II

1967 ◽  
Vol 22 (8) ◽  
pp. 1141-1156
Author(s):  
I. Hertel ◽  
Ch. Ottinger
Keyword(s):  
Rate Constants ◽  
Mass Spectra ◽  
Relative Rate ◽  
Absolute Magnitude ◽  
Observation Time ◽  
Energy Scale ◽  
High Rate ◽  
Empirical Parameter ◽  
Relative Rate Constants ◽  
Straight Lines

The previously described apparatus for the measurement of decomposition times of short-lived organic ions has been modified. With the improved version the accessible range of times between ionization and decomposition extends now from about 5·10-9 sec to 5·10-6 sec, although in one case times as short as 3 · 10-9 sec could be distinguished. The substances studied were benzonitrile, n-butane, n-heptane and benzene. The logarithm of the differentially measured decomposition rate was plotted versus the logarithm of the time. All of these plots were found to be straight lines, indicating approximate decomposition laws di/dt ∼ t-r. From the empirical parameter r the distribution of rate constants contributing to the overall decay was evaluated. This distribution led to a determination of the function k(E) which describes the increase of the rate constant k with increasing internal energy E in the ion and is an important molecular property, hitherto only calculable under various assumptions. The calibration of the energy scale of k(E) was based on previous measurements of ionization curves of “normal” and “metastable” fragments. The k(E)-curves for butane and heptane are compared with the most recent experimental and theoretical breakdown curves, with generally good agreement with regard to the energy scale and relative rate constants. The absolute magnitude of the rate constants is surprisingly small and the rise with energy quite slow. It appears that for the decomposition of benzonitrile no rate constants larger than 5·108 sec-1 occur. The amount of fragmentation taking place in times shorter than 10-8 sec was accordingly found to be much smaller than generally assumed; in benzonitrile only 35% of all mass 76 fragments present after 10-6 sec are formed within the first 10-8 sec.For butane and heptane partial mass spectra for an observation time of 10-8 sec could be evaluated. They are significantly different from the ordinary mass spectra due to different decomposition laws for different fragments.For benzonitrile, the decomposition function was also measured for different electron energies, starting near threshold. The expected result, a decreasing contribution from high rate constants with decreasing Uel, was established and also reproduced by a calculation.

The combination of methyl radicals: photolysis of acetone at low pressures

1954 ◽  
Vol 223 (1154) ◽  
pp. 283-295 ◽  
Keyword(s):  
Relative Rate ◽  
Methyl Radicals ◽  
Third Body ◽  
Low Pressures ◽  
Kinetics Of ◽  
Photo Decomposition ◽  
Activated Complex

The kinetics of the photo-decomposition of acetone at low pressures (20 to 0.2 mm) are consistent with the participation of a third body in the recombination of methyl radicals. Various added gases increase the relative rate of formation of ethane; approximate values, relative to acetone, are given for their efficiencies in deactivating excited ethane molecules by collision. The rate of spontaneous redissociation of the activated complex is less than 6 x 10 7 s -1 at 520° K, and increases with temperature.

scholarly journals Activated Carbon Preparation from Eucalyptus Wood Chips using Continuous Carbonization - Steam Activation Process in a Batch Intermittent Rotary Kiln

2020 ◽  
Author(s):  
Sumrit Mopoung ◽  
Nuchjira Dejang
Keyword(s):  
Activated Carbon ◽  
Rotary Kiln ◽  
Carbon Materials ◽  
Activated Carbons ◽  
Wood Chips ◽  
Bet Surface Area ◽  
Activation Process ◽  
Steam Activation ◽  
Activation Temperature ◽  
Eucalyptus Wood

Abstract The production of activated carbon from eucalyptus wood chips by steam activation in a 2000 kg batch intermittent rotary kiln with continuous carbonization - steam activation process at 500°C to 700 °C was studied. The activated carbon products were characterized by FTIR, SEM-EDS, Raman spectroscopy, and BET analyzer. Percent yields, iodine number, and methylene number of the produced activated carbon materials were also measured. It was shown that the percent yield of the activated carbon materials made in the temperatures range of 500°C to 700 °C are 21.63 ± 1.52% − 31.79 ± 0.70% with capacities of 518–737 mg I2/g and 70.11–96.93 mg methylene blue /g. The BET surface area and micropore volume of the activated carbons are 426.8125-870.4732 m2/g and 0.102390–0.215473 cm3/g, respectively. The steam used in the process could create various oxygen containing surface functional groups such as –CO and –COC groups. In addition, it could also increase the amorphous nature of the activated carbon product. These properties of the activated carbon products are increased with increasing steam activation temperature from 500°C to 700°C. As a result, the activated carbon materials produced at activation temperatures of 600 °C and 700 °C have higher adsorption

scholarly journals Water cluster in hydrophobic crystalline porous covalent organic frameworks

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ke Tian Tan ◽  
Shanshan Tao ◽  
Ning Huang ◽  
Donglin Jiang
Keyword(s):  
Water Cluster ◽  
Water Exchange ◽  
Capillary Condensation ◽  
Water Molecules ◽  
Covalent Organic Frameworks ◽  
High Uptake ◽  
One Dimensional ◽  
The Past ◽  
Low Pressures ◽  
Small Hydrophobic

AbstractProgress over the past decades in water confinement has generated a variety of polymers and porous materials. However, most studies are based on a preconception that small hydrophobic pores eventually repulse water molecules, which precludes the exploration of hydrophobic microporous materials for water confinement. Here, we demonstrate water confinement across hydrophobic microporous channels in crystalline covalent organic frameworks. The frameworks are designed to constitute dense, aligned and one-dimensional polygonal channels that are open and accessible to water molecules. The hydrophobic microporous frameworks achieve full occupation of pores by water via synergistic nucleation and capillary condensation and deliver quick water exchange at low pressures. Water confinement experiments with large-pore frameworks pinpoint thresholds of pore size where confinement becomes dominated by high uptake pressure and large exchange hysteresis. Our results reveal a platform based on microporous hydrophobic covalent organic frameworks for water confinement.

scholarly journals Activated carbon preparation from eucalyptus wood chips using continuous carbonization–steam activation process in a batch intermittent rotary kiln

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sumrit Mopoung ◽  
Nuchjira Dejang
Keyword(s):  
Methylene Blue ◽  
Activated Carbon ◽  
Rotary Kiln ◽  
Carbon Materials ◽  
Wood Chips ◽  
Bet Surface Area ◽  
Activation Process ◽  
Steam Activation ◽  
Eucalyptus Wood ◽  
Bet Analysis

AbstractThe production of activated carbon from eucalyptus wood chips by steam activation in a 2000 kg batch intermittent rotary kiln with continuous carbonization–steam activation process conducted at 500 °C to 700 °C was studied. The activated carbon products were characterized by FTIR, SEM–EDS, Raman spectroscopy, and BET analysis. Percent yields, iodine number, and methylene blue number of the produced activated carbon materials were measured as well. It was shown that the percent yields of the activated carbon materials made in the temperature range from 500 to 700 °C are 21.63 ± 1.52%–31.79 ± 0.70% with capacities of 518–737 mg I2/g and 70.11–96.93 mg methylene blue/g. The BET surface area and micropore volume of the activated carbons are 426.8125–870.4732 m2/g and 0.102390–0.215473 cm3/g, respectively. The steam used in the process could create various oxygen containing surface functional groups such as –CO and –COC groups. In addition, it could also increase the amorphous nature of the activated carbon product. These properties of the activated carbon products are increased with increasing steam activation temperature from 500 to 700 °C. As a result, the activated carbon materials produced at activation temperatures of 600 °C and 700 °C exhibit higher adsorption.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

Sign in / Sign up

Export Citation Format

Share Document