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1.
A. A. Pribylov I. A. Kalinnikova S. M. Kalashnikov G. F. Stoeckli 《Russian Chemical Bulletin》2000,49(4):692-700
The isotherms of excess adsorption of CH4 (atP=0.001–160 MPa), SF6 (atP=0.001–2.4 MPa), and C6H6 (atP=0.0001–0.1 MPa) on carbon adsorbents—microporous carbons CMS and FAS with developed mesoporosity and graphitized soot—were
measured in the 298–408 K temperature region. Calculation of the isotherms of absolute adsorption of the total content of
these substances requires knowledge of the adsorption volume, which was determined by different methods: by the Dubinin—Radushkevich
equation; by the experimental isotherm of excess adsorption and the equation of absolute adsorption; by the method using the
intersection of nonlinear isosteres of excess adsorption and isosteres of absolute adsorption; by the comparative plot of
values of the excess C6H6 adsorption ΓFAS—Γsoor; by the method using the difference of molecular radii of adsorptives and the surface of the specific adsorbent; and by the
calculation of the adsorption layer thickness using the FHH equation for mesoporous systems. The results of determination
of the adsorption volume for microporous systems of these carbons agree well with each other and with the passport data for
the adsorbents. Analysis of the results revealed the peculiarity of the sulfur hexafluoride adsorption related to the formation
of associates on the surface of the carbon adsorbents.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 688–696, April, 2000. 相似文献
2.
The paper describes results obtained within the study of factors affecting the process of an antifungal drug — terbinafine
hydrochloride adsorption on two different adsorbents — charcoal and silicagel. The effects of the adsorbent area, pH value,
temperature and additives (polymers — methyl cellulose and hydroxypropyl cellulose) were analyzed and their impact on the
adsorption of terbinafine was derived. The increase of pH and temperature, and the presence of additives decreased the amount
of terbinafine adsorbed on the adsorbents. Terbinafine is currently applied both perorally and topically. Hydrogels, i.e.
compositions of a drug, additives and water, are, due to their advantageous properties, preferred topical dosage forms. Mass
fraction of additives of 1 % to 4 % were studied from the view point of drug release. This study shows that both the sort
and the concentration of polymers influence the drug release from hydrogels significantly. 相似文献
3.
G. I. Berezin R. Sh. Vartapetyan A. M. Voloshchuk G. A. Petukhova N. S. Polyakov 《Russian Chemical Bulletin》1998,47(10):1879-1885
The mechanism of adsorption of water molecules on nonporous carbon adsorbents has been suggested in terms of two different
states of adsorbed water; stretched liquid water and water that occupies an intermediate state between the liquid and vapor.
Two stages of adsorption were distinguished: condensation and pre-condensation that assumes the formation of molecular associates.
The BET model was used to describe the pre-condensation stage. The equations of the adsorption isotherm for water vapor in
the region of condensation process and the expression for the determination of the specific hydrophilic surface of adsorbents
were found. Examination of the experimental data on adsorption of water vapor on nongraphitized samples of carbon adsorbents
shows that in the region of polymolecular adsorption, all isotherms fall into a common curve determined by the equation of
the stretched liquid film and can be calculated regardless of the properties of individual liquid water. The equation for
adsorption of water vapor on the hydrophobic surface was obtained.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1933–1939, October, 1998. 相似文献
4.
Yu. I. Tarasevich E. V. Aksenenko S. V. Bondarenko A. I. Zhukova V. E. Polyakov 《Theoretical and Experimental Chemistry》2008,44(5):325-330
The molecular statistical method for evaluating the distribution of active sites of various adsorbents relative to their energies
has been improved. This method is used not only for the treatment of experimental data on the adsorption of hydrocarbons on
various adsorbents, which is the usual procedure, but also data on the adsorption of polar water and methanol molecules on
the active sites of adsorbent surfaces. Two types of active sites differing in energy have been shown to exist on the surface
of graphitized carbon black, the complex shungite carbon/mineral adsorbent, and modified Silochrom. Chromatographic, calorimetric,
and structural adsorption data were used to establish the relationship between the observed maxima of the energy distribution
function of the adsorption sites with concrete adsorption sites or pores of the surface, on which the molecules are adsorbed.
Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 44, No. 5, pp. 315–320, September–October, 2008. 相似文献
5.
Magnetic separation technology was applied in the separation of flavonoids from the licorice root in this work. Licorice flavonoids
(LF) displayed a remarkable array of biological and pharmacological activities. The magnetic adsorbents with functional —NH2 groups were synthesized by immobilization of amino-silane on the surface of the magnetic silica supports, which were prepared
by co-precipitation method. The adsorption and desorption characteristics of the magnetic adsorbents for the separation of
LF have been evaluated. The purity of an enriched extract with this method was 16.7% while the crude extract only had about
6.8% purity. Therefore, it can be concluded that these kinds of magnetic adsorbents have selectivity to the flavonoids to
some extent. The affinity selectivity of the adsorbents is based on the formation of hydrogen bonding between the —NH2 on the magnetic adsorbents and —OH, —CO on the flavonoids.
Supported by the National High Technology Research and Development Program of China (Grant No. 2002AA302211) and the National
Science Fund for Creative Research Groups of China (Grant No. 20221603) 相似文献
6.
Methane adsorption on the microporous carbon adsorbent AUK was calculated on the basis of Dubinin’s theory of volume filling
of micropores in the temperature range 177.7—393 K and at pressures from 1 Pa to 6 MPa. The calculated isotherms of absolute
adsorption were compared with the isotherms of methane obtained experimentally. Good agreement between the calculated and
experimentally measured amounts adsorbed is observed in the area of applicability of the theory at micropore ranging in coverage
θ from 0.25 to 0.95. The adsorption isosters were calculated for the same pressure and temperature ranges. The adsorption
isosters satisfactorily represent the temperature dependence of the amount of methane adsorbed obtained experimentally. The
calculations gave for the thermal coefficient of limiting adsorption a value of 6hcalc = 1.64• 10-3 K-1., which exceeds the experimental value by ∼15%. 相似文献
7.
A statistical approach was applied to describe the model of a homogeneous microporous adsorbent and obtain the dependences
of the thermodynamic functions on the number of molecules and the temperature for molecular aggregates in discrete micropores
over a wide region of fillings that lead to the Dubinin—Radushkevich equation. The energy nonuniformity of the adsorption
space is the fundamental property of carbon adsorbents. In the region of small fillings, the statistical approach leads to
Henry's law and the finite value of the initial differential energy of adsorption. The value of sorption corresponding to
the saturated vapor pressure decreases with increasing temperature, but the decrease is considerably less than for the density
of the corresponding liquid.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 261–265, February, 1999. 相似文献
8.
A. A. Pribylov I. A. Kalinnikova L. G. Shekhovtsova V. A. Davankov M. P. Tsyurupa 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(5):837-842
The adsorption of methane on MN-200 and MN-270 polymer adsorbents, and on active carbon D4609, is investigated in the pressure
range of 0.1–40 MPa at temperatures of 303, 323, 343, 373 K. Adsorption volumes are determined for these adsorption systems,
and the isosteric heats of adsorption are calculated. Based on our investigations, we consider the possibility of storing
methane in the adsorbed state in containers and the efficiency of the approach relative to gas storage in containers without
adsorbents. Recommendations on selecting an adsorbent for methane storage are given, and one possible way of increasing the
amount of stored gas is described. 相似文献
9.
Estimation of micropore size distribution in active carbons from adsorption isotherms of water vapor
A possibility of estimation of the micropore size distribution in the carbon adsorbents with the developed micro-and mesoporous
structure by analysis of the adsorption isotherms of water vapors was considered. At saturation water condenses in micropores
in a form of a weakly compressed liquid. However, water molecules in micropores are packed not so closely as in the liquid
because of steric hindrance. Therefore, the real density of water adsorbed in the micropores is lower than that of water adsorbed
on an open surface and lower than the density of the normal liquid. An analysis of the adsorption isotherms of water vapors
with account for the both opposite effects on the water density gives reliable data on the micropore sizes of the carbon adsorbents.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 40–43, January, 2007. 相似文献
10.
The adsorption isosteres and isotherms of methane on the microporous carbon adsorbent PAU-10 were calculated using the Dubinin—Radushkevich
equation taking into account nonideality of the gas phase. The conditions under which the adsorption isosteres are linear
were outlined. The calculated and experimentally found adsorption isosteres were compared for the methane—PAU-10 system. The
slope of the isosteres remains unchanged on going to the region of strong nonideality of the gas phase.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 382–385, March, 2007. 相似文献
11.
A model for the dynamics of isothermal absorption of a binary mixture of an organic substance, soluble in water, and water
vapor in a fixed bed of activated carbon was proposed. It includes the equations of material balance and the Myers—Prausnitz
model for equilibrium adsorption. The possibility of formation of the condensed phase during the adsorption of an organic
substance on moist activated carbon was shown.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1491–1495, August, 1998. 相似文献
12.
Comparative analysis of methods for determination of structural characteristics of carbon adsorbents
A. A. Pribylov L. G. Shekhovtsova I. A. Kalinnikova 《Russian Chemical Bulletin》2005,54(10):2290-2298
Experimental data on the equilibrium adsorption of sulfur hexafluoride, methane, carbon dioxide, and benzene on carbon adsorbents
of different porosity obtained in a wide pressure range at 298–408 K were analyzed. The adsorption volumes, surface areas,
and sizes of slit-shaped pores of the carbons were determined using several independent methods. A method for determination
of the adsorption volume from the experimental isotherm of excessive adsorption of gases and the total content equation was
proposed. The resulting values are similar to the adsorption volumes calculated from the data for vapors. A new method for
the calculation of the adsorbent surface area is described. The method is based on the dependence of the adsorption volume
of adsorbent pores on the effective size of adsorbate molecules. A possibility to determine the average size of narrow slit-shaped
carbon pores from the difference of the initial heats of adsorption of the gas under study on the carbon black and porous
carbon adsorbent is considered.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2219–2227, October, 2005. 相似文献
13.
The relative adsorption deformation of several microporous carbon adsorbents was studied as a function of the benzene adsorption
at relative pressure ranging from 1·10−1 to 1.0 and at 293 K. A correlation between the maximum compression of the sample and the characteristic energy of benzene
adsorption of the Dubinin-Radushkevich equation was obtained. Using data on the adsorption deformation, it is possible to
identify the region with a specific pore size that cannot be evaluated with the help of the Dubinin-Radushkevich equation.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No.6, pp. 1018–1022, June, 2000. 相似文献
14.
Biomaterial immobilization in nanoporous carbon molecular sieves: influence of solution pH, pore volume, and pore diameter 总被引:1,自引:0,他引:1
The adsorption of lysozyme (Lz) onto nanoporous carbon molecular sieves with various pore diameters has been studied at different solution pH values. All the adsorption isotherms have successfully been correlated by the Langmuir equation. The amount of adsorbed Lz depends on the solution pH as well as on the specific pore volume and pore diameter of the adsorbents. The maximum adsorption was observed near the isoelectric point of the Lz (pI approximately 11), suggesting that suppression of electric repulsion between the enzymes plays an important role in the adsorption process. Moreover, the amount adsorbed depends on the pore size and pore volume of the nanoporous carbon adsorbents, indicating that the Lz molecules are adsorbed inside the mesopores. CMK-3-150 shows a larger amount of Lz adsorption as compared to CMK-3. The increased Lz adsorption capacity of CMK-3-150 may be due to the larger pore volume and pore diameter as compared to that of CMK-3. The unaltered structural order of the nanoporous adsorbents after the adsorption has been confirmed by the physicochemical characterization techniques such as XRD and N(2) adsorption. In addition, FT-IR spectroscopic studies confirm that the Lz used in this study is stable even after the adsorption on the nanoporous carbon. These results indicate that nanoporous carbon has superior water stability and thus is a more appropriate adsorbent for biomaterials than nanoporous silica. 相似文献
15.
Analytical methods for arsine, silane and dichlorosilane by adsorption sampling and elemental analysis with graphite furnace AA were studied to establish convenient methods for atmospheric contamination surveys. This study included the following five items: (1) primary selection of adsorbents applicable to adsorption sampling; (2) examination of the adsorption capacities of the adsorbents for the gases; (3) improvement of the adsorbents by chemical modification; (4) desorption of the gases adsorbed on the adsorbents with solvents; and (5) quantitative analysis of arsenic and silicon in the solutions. Experimental results showed that active carbon made from synthetic thermosetting resin beads contained no aresenic and little silicon as impurities. This active carbon by itself was proved to adsorb arsine and dichlorosilane, but not silane. Impregnation with sodium hydroxide of the active carbon improved the adsorption capacity for all three gases. Refined silica gel, free from arsenic contamination, did not adsorb arsine by itself but potassium permanganate impregnation produced an adsorption capacity for arsine. The adsorbed arsine on the active carbon was desorbed into a hot dilute nitric acid solution with high efficiency (over 90%), but arsine adsorbed on sodium hydroxide impregnated active carbon or on potassium permanganate impregnated silica gel was dissolved into various solutions only at lower efficiencies. Silane adsorbed on sodium hydroxide-impregnated active carbon was desorbed with hot water with an efficiency higher than 90%. Dichlorosilane adsorbed on the active carbon with or without sodium hydroxide impregnation was desorbed with a nitric acid solution with efficiency of 85%. The lower determination limit for arsine able to discriminate from background interference of arsenie was 0.005 ppm, and those for silane and dichlorosilane were each 0.05 ppm for 3-dm3 air samples. 相似文献
16.
Adsorption isotherms of carbon dioxide on microporous carbon adsorbents prepared by activation with potassium sulfide in water
vapor were measured. The measurements were carried out in the pressure interval from 1 Pa to 0.1 MPa at temperatures from
216.2 to 293.15 K. Based on the theory of volumetric filling of micropores, the main structural and energetic parameters of
the microporous carbon adsorbents were calculated. The adsorption isosters of carbon dioxide were calculated from the adsorption
isotherms in the same pressure and temperature ranges and approximated by linear dependences. The plots of the differential
mole isosteric heats of adsorption vs amount adsorbed were constructed by using the adsorption isosters. 相似文献
17.
Adsorption of n-butanol and water from butanol–water mixtures is studied on adsorbents of different hydrophobicity (activated carbon and
hydrophobized montmorillonites). The shape of the adsorption isotherms of the hydrophobized clay minerals does not indicate
preferential adsorption of butanol. Therefore, the adsorption capacity cannot be determined on the basis of the Langmuir isotherm.
A new equation for determining the adsorption capacity is derived by combining the free enthalpy of adsorption with the adsorption
excess amount. Both collections of data are obtained from the surface excess isotherm. The reliability of the adsorption capacity
is checked by X-ray diffraction measurements.
Received: 1 November 1997 Accepted: 19 February 1998 相似文献
18.
Gun'ko V. M. Mikhalovskii S. V. Melillo M. Voronin E. F. Nosach L. V. Pakhlov E. M. 《Theoretical and Experimental Chemistry》2004,40(3):137-143
The interaction of ibuprofen [2-(4-isobutylphenyl)propionic acid] with the surface of carbon and oxide adsorbents was investigated. The significant role of wide pores during the adsorption of ibuprofen on carbon adsorbents in the presence of protein molecules was demonstrated. At low concentrations ibuprofen is adsorbed on the surface of hydrophilic and hydrophobic adsorbents in the form of a monomer, but the contribution from the adsorbed dimer increases with increase in its concentration. 相似文献
19.
氢气在炭狭缝微孔内吸附的预测 总被引:1,自引:0,他引:1
通过边界的平均场近似,推导二平板狭缝孔格子理论Ono-Kondo吸附等温方程.利用格子气模型特性和微观物理学理论,计算氢分子在石墨平面的最大吸附容量.比较由氢分子在石墨平面二典型聚集状态标定的Ono-Kondo方程,并用预测精度较高的方程计算了与文献相同条件下的吸附等温线.在比较了计算结果、试验结果和GCMC分子模拟结果后,对Ono-Kondo吸附等温方程的特点、理论基础作了分析,指出了方程的适用范围. 相似文献
20.
The isotherms describing excess adsorption of SF6 and N6I6 on carbon adsorbents with different pore structures were measured at pressures of 0.001—2.4 and 0.0001—0.1 MPa, respectively, and temperatures of 298—408 E. A linear dependence of Henry"s constant on temperature in the lnK—103/O coordinates was found for all the samples. The specific surface areas of the samples determined by the BET method from the SF6 adsorption are lower than those derived from benzene adsorption. The most pronounced difference was found for the grafitized carbon black. When SF6 was adsorbed on supermicroporous carbon AC-71 and on microporous carbons PAC and CMS, a hysteresis was found, which, unlike that on mesoporous carbon adsorbents, is observed in the initial region of the equilibrium pressures. 相似文献