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1.
Mohammad Mehdi Papari Reza Behjatmanesh-Ardakani Masoumeh Kiani Jalil Moghadasi Antonio Campo 《Colloid and polymer science》2011,289(10):1081-1087
This paper addresses a method for predicting the participating constants in equation of state (EOS) for compressed polymeric
fluids using two scaling constants, the surface tension γ
g and the molar density ρ
g, both at the glass transition point. The theoretical EOS undertaken is the one attributed to Tao and Mason. The second virial
coefficients are calculated from a two-parameter corresponding states correlation, which is constructed with two constants
as scaling parameters, i.e., the surface tension γ
g and the molar density ρ
g. This new correlation has been applied to the Tao–Mason (TM) EOS to predict the volumetric behavior of several polymer melts.
The operating temperature range is from 291.25 to 603.4 K and pressures of up to 202.5 MPa. A collection of 516 data points
has been examined for the aforementioned polymers. The average absolute deviation between the calculated densities and the
experimental ones is of the order of 0.44%. 相似文献
2.
We have investigated a practical lower limit of a pore-size estimation by the nitrogen desorption isotherms at 77 K using
the Kelvin equation. Changes in pore size of porous silica glasses before and after the monolayer preadsorption of n-propylalcohol were estimated by measuring the nitrogen adsorption and desorption isotherms. These changes should correspond
to the thickness of monolayer of adsorbed n-propylalcohol. The thickness of monolayers obtained for the samples whose pore sizes are below ca. 2 nm were underestimated,
when the Kelvin equation was applied to the nitrogen desorption isotherms using the values of surface tension and molar volume
of bulk liquid nitrogen at 77 K. Below ca. 2 nm pore radius a careful application of the Kelvin equation is required to estimate
a pore size. These results suggest that a change in the physical properties of liquid nitrogen in such a small pore occurs.
It is supposed that the interaction between the solid surface and adsorbate molecules causes the changes in the surface tension
and density of liquid nitrogen in such a narrow pore.
Received: 21 March 1997 Accepted: 18 July 1997 相似文献
3.
M. Paluch 《Colloid and polymer science》1998,276(7):648-652
The results of experimental studies of the adsorption at the solution/air interface from an aqueous mixture: 2,4,6-trimethylphenol–2,4,6-trichlorophenol
are presented. The surface properties of the above-mentioned mixture were studied by surface potential and surface tension
measurements. These measurements were carried out as a function of the concentration of 2,4,6-trimethylphenol aqueous solution
at a constant concentration of 2,4,6-trichlorophenol.
Using the results obtained and based on the Gibbs equation, Helmholtz formula and Motomura’s method the relative surface excesses
of adsorbed substances, effective dipole moments, surface molar fractions of solutes and miscibility of adsorbed films were
determined.
Received: 7 November 1997 Accepted: 26 February 1998 相似文献
4.
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
5.
Rau María S. Gennero de Chialvo María Rosa Chialvo Abel C. 《Journal of Solid State Electrochemistry》2012,16(5):1893-1900
The carbon monoxide oxidation reaction (COOR) was studied on steady-state conditions by chronoamperometry on polycrystalline
smooth platinum and ruthenium rotating disc electrodes in CO-saturated acid solution. The chronoamperometric response did
not show current oscillations and therefore the current density (j) vs. overpotential (η) curves on steady state could be obtained. In order to interpret these results, kinetic expressions were derived starting
from the mechanism proposed by S. Gilman, which considers two adsorbed reaction intermediates, carbon monoxide (COad) and hydroxyl (OHad). Analytical expressions as a function of overpotential for the current density, the surface coverage of the adsorbed species
(θ
CO and θ
OH) and the CO and CO2 pressures at the electrode surface on steady state were obtained. This set of equations was used for the correlation of the
experimental polarization curves and the evaluation of the corresponding kinetic parameters. From these values, the dependences
of the surface coverage of the adsorbed intermediates on overpotential were simulated, as well as those of the partial pressure
of CO and CO2. Thus, it was demonstrated that the Gilman’s mechanism accurately describes the experimental results on steady state of the
COOR on these metals. 相似文献
6.
The apparent molar volumes, V
φ
, of glycine, L-alanine and L-serine were obtained in aqueous 0 to ∼4 mol⋅kg−1 N,N-dimethylacetamide (DMA) solutions from density measurements at 298.15 and 308.15 K. The standard partial molar volume,
V
φ
o, and standard partial molar volumes of transfer, Δtr
V
φ
o, were determined for these amino acids. It has been shown that hydrophilic-hydrophilic interactions between charged groups
of the amino acids and the —CON= group of DMA are predominant in the case of glycine and L-serine, but for L-alanine the interactions
between its side group (—CH3) and DMA are predominant. An increase in temperature increases the standard partial molar volumes but decreases the transfer
volumes of the amino acids. The results have been interpreted in terms of cosphere overlap model. 相似文献
7.
Summary The pressure-area curves for neutral monolayers of butyric, valeric, caproic and caprylic acids at the airwater interface
were obtained from the surface tension concentration data. Similar curves for the charged monolayers of sodium octanoate and
sodium lauryl sulphate in the presence and absence of excess neutral salts were constructed on the basis of the results on
surface tension. From the comparison of the pressure area curves of each of these monolayers at air-water and oil-water interfaces
under identical conditions, the cohesive pressures of the monolayer at the air-water interface were calculated for different
areas per adsorbed molecule using the equation ofDavies. The cohesive pressure was observed to vary linearly with the square of the reciprocal area per adsorbed molecule or ion.
From the slope of such linear plot, magnitude of the two-dimensionalvan der Waals constant in each case was estimated. The thickness of the interfacial film was estimated from the comparison of the values
of two- and three-dimensionalvan der Waals constants. This is, however, found to be considerably greater than the length of the stretched molecules adsorbed at the
interface. When correction for entropy, as suggested byGershfeld is introduced, the film thickness becomes identical with the length of the molecule.
Based in part upon the thesis submitted byA. K. Chatterjee for the Ph. D. degree of the Jadavpur University (1966). 相似文献
8.
L. H. Blanco O. M. Vargas A. F. Suárez 《Journal of Thermal Analysis and Calorimetry》2011,104(1):101-104
In this study, a systematic study of the effect of the temperature on the density and surface tension of HMT (hexamethylentetramine)
in water was developed. The density and surface tension were determined at temperatures of 288.15, 293.15, 298.15, 303.15,
and 308.15 K. Precise data of surface tension have not been reported previously in literature. From the density measurements,
the apparent molar and partial molar volumes were calculated. The apparent molar volume decreases with concentration, the
molar partial volume increases with temperature. The surface tension of the aqueous solutions of HMT decreases with concentration.
The excess surface concentration was calculated, the values increase with concentration, indicating that the amount of HMT
that goes to the interface gas liquid increases at higher concentrations of HMT. 相似文献
9.
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
10.
Dispersive liquid—liquid microextraction coupled with high-performance liquid chromatography—diode-array detection was applied
for the extraction and determination of 11 priority pollutant phenols in wastewater samples. The analytes were extracted from
a 5-mL sample solution using a mixture of carbon disulfide as the extraction solvent and acetone as the dispersive solvent.
After extraction, solvent exchange was carried out by evaporating the solvent and then reconstituting the residue in a mixture
of methanol–water (30:70). The influences of different experimental dispersive liquid—liquid microextraction parameters such
as extraction solvent type, dispersive solvent type, extraction and dispersive solvent volume, salt addition, and pH were
studied. Under optimal conditions, namely pH 2, 165-μL extraction solvent volume, 2.50-mL dispersive solvent volume, and no
salt addition, enrichment factors and limits of detection ranged over 30–373 and 0.01–1.3 μg/L, respectively. The relative
standard deviation for spiked wastewater samples at 10 μg/L of each phenol ranged between 4.3 and 19.3% (n = 5). The relative recovery for wastewater samples at a spiked level of 10 μg/L varied from 65.5 to 108.3%. 相似文献
11.
The dynamics of a decrease in the surface tension is studied for aqueous solutions of sodium dodecyl sulfate and its mixtures
with lower alcohols (ethanol and n-propanol). Two approaches are analyzed as applied to the estimation of the adsorption of two surfactants from their mixed
solutions at a liquid—gas interface, i.e., the Frumkin generalized model and the Fainerman—Miller model. It is shown that
both approaches adequately describe the concentration dependences experimentally measured for the surface tension of sodium
dodecyl sulfate—lower alcohol mixtures. 相似文献
12.
I. M. Abdulagatov A. Tekin J. Safarov A. Shahverdiyev E. Hassel 《Journal of solution chemistry》2008,37(6):801-833
The density of five (0.02297, 0.08317, 0.26147, 0.49343, 0.75255 mole fraction BMIMPF6) binary methanol + BMIMPF6 (1-n-butyl-3-methylimidazolium hexafluorophospate) mixtures have been measured with a vibrating-tube densimeter. Measurements
were performed at temperatures from 298 to 398 K and at pressures up to 40 MPa. The total uncertainties of the density, temperature,
pressure, and concentration (mole fractions) measurements were estimated to be less than 0.1 kg⋅m−3, 15 mK, 5 kPa, and 10−4, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95% confidence level with a coverage
factor of k=2. The measured densities were used to study of the effect of temperature, pressure, and concentration on the derived volumetric
properties such as excess, apparent and partial molar volumes. It is shown that the values of excess molar volume for methanol + BMIMPF6 mixtures are negative at all measured temperatures and pressures in the whole concentration range. The measured densities
were used to develop Tait-type equations of state for pure components and the mixtures. The structural properties such as
direct and total correlation function integrals were calculated using the derived partial molar volumes at infinite dilution. 相似文献
13.
Parimal C. Dey Muhammad A. Motin Tapan K. Biswas Entazul M. Huque 《Monatshefte für Chemie / Chemical Monthly》2003,37(2):797-809
The apparent molar volume (φv) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φv) of the carbohydrates was found to be a linear function of the concentration. From a φv versus molality (b) plot, the apparent molar volume at infinite dilution (), which is practically equal to the partial molar volume at infinite dilutions () of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG ≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of solute–solvent interactions. 相似文献
14.
G. I. Berezin M. L. Gubkina G. A. Petukhova N. S. Polyakov 《Russian Chemical Bulletin》1999,48(4):663-666
A two-stage mechanism of adsorption, including nucleation and condensation, was proposed to describe the formation of the
water liquid phase in carbon adsorbents. Adsorption is assumed to occur in cylindrical pores. Nucleation is described by a
modified BET model, and condensation is treated by the model of a stretched liquid film on a bent surface. The onset of formation
of the liquid phase (OFLP) is determined from the intersection of the adsorption isotherms for these stages. The theoretical
value of the relative pressure of OFLP varies over a wide range, decreasing with a decrease in the pore radius and reactiing
the relative vapor pressure of 0.178 for the spinodal state of water. The comparison method using isotherms of graphitized
carbon black as the reference isotherms was applied for the determination of OFLP of water in real active carbons. This resulted
in good agreement between theory and experiment.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 668–671, April, 1999. 相似文献
15.
Kelei Zhuo Qiufen Zhang Xiaopeng Xuan Hucheng Zhang Jianji Wang 《Frontiers of Chemistry in China》2007,2(2):193-198
Densities have been measured for Glucose + HCl +Water at 10-degree intervals from 278.15 to 318.15 K. The apparent molar volumes
(V
Φ,G) and standard partial molar volumes (V
Φ,G
0
) for Glucose in aqueous solution of 0.2, 0.4, 0.7, 1.1, 1.6, 2.1 mol·kg−1 HCl have been calculated as well as volumetric interaction parameters (V
EG) for Glucose — HCl in water and standard partial molar expansion coefficients (∂V
Φ,G
0
/ ∂T)p. Results show that (1) the apparent molar volume for Glucose in aqueous HCl solutions increases lineally with increasing
molality of Glucose and HCl; (2) V
Φ,G/0 for Glucose in aqueous HCl solutions increases lineally with increasing molality of HCl; (3) the volumetric interaction parameters
for Glucose — HCl pair in water are small positive and vary slightly with temperature; (4) the relation between V
Φ,G
0
and temperature exists as V
Φ,G
0
= a
0 + a
1(T − 273.15 K)2/3; (5) values of (∂V
Φ,G
0
/ ∂T)p are positive and increase as temperatures rise, and at given temperatures decrease slightly with increasing molalities of
HCl, indicating that the hydration of glucose decreases with increasing temperature and molality of HCl. These phenomena are
interpreted successfully by the structure interaction model.
Translated from Acta Chimica Sinica, 2006, 64(16): 1635–1641 (in Chinese) 相似文献
16.
Monica Spinu Nuno Dos Santos Nicolas Le Moigne Patrick Navard 《Cellulose (London, England)》2011,18(2):247-256
The swelling and dissolution capacity of dried and never-dried hardwood and softwood pulps and cotton linters was compared
in two aqueous solvents, N-methylmorpholine-N-oxide (NMMO)-water at 90 °C with water contents ranging from 16 to 22% and NaOH—water at −6 °C with NaOH contents ranging
from 5 to 8%. Swelling and dissolution mechanisms were observed by optical microscopy and dissolution efficiency was evaluated
by recovering insoluble fractions. The results show a contrasted picture towards the effect of the never-dried state on the
swelling and the dissolution capacity depending on the origin of the fibres and the type of aqueous solvent. In the case of
NMMO—water, the presence of water within and around the fibre does not seem to favour dissolution initiation but after 2 h
of mixing the dissolution yield appears to be similar for either dried or never-dried state. The limiting factor for dissolution
in NMMO—water is not the penetration of the solvent inside the cellulose fibres, but only the local concentration of NMMO
molecules around the fibre. For NaOH—water, both optical microscopy observations on individual fibres and dissolution yield
measurements show that the never-dried state is more reactive for softwood pulps and cotton linters and has no significant
effect on hardwood pulps. In this case, the local decrease of solvent strength is counteracted by the opening of the structure
in the never-dried state which should enable the Na+ hydrated ions to penetrate easier. 相似文献
17.
The density and surface tension of the pure ionic liquid 1-butyl-3-methyl-imidazolium l-lactate were measured from T (293.15 to 343.15) K. The coefficient of thermal expansion, molecular volume, standard entropy, lattice energy, surface entropy, surface enthalpy, and enthalpy of vaporization were calculated from the experimental values. Density and surface tension were also determined for binary mixtures of {1-butyl-3-methyl-imidazolium l-lactate + water/alcohol (methanol, ethanol, and 1-butanol)} systems over the whole composition range from T (298.15 to 318.15) K at atmospheric pressure. The partial molar volume, excess partial molar volume and apparent molar volume of the component IL and alcohol/water in the binary mixtures were discussed as well as limiting properties at infinite dilution and the thermal expansion coefficients of the four binary mixtures. The surface properties of the four binary mixtures were also discussed. 相似文献
18.
Vapor pressures of six aqueous lithium nitrate solutions with molalities of (0.181, 0.526, 0.963, 1.730, 2.990, and 5.250) mol-kg–1 have been measured in the temperature range 423.15–623.15 K with a constant-volume piezometer immersed in a precision liquid thermostat. The static method was used to measure the vapor pressure. The total uncertainty of the temperature, pressure and composition measurements were estimated to be less than 15 mK, 0.2%, and 0.014%, respectively. The vapor pressures of pure water were measured with the same apparatus and procedure to confirm the accuracy of the method used for aqueous lithium nitrate solutions. The results for pure water were compared with high-accuracy PS–TS data calculated from the IAPWS standard equation of state. Important thermodynamic functions (activities of water and lithium nitrate, partial molar volumes, osmotic coefficient, excess relative partial molar entropy, and relative partial molar enthalpy values of the solvent) were derived using the measured values of vapor pressure for the solution and pure water. The measured and derived thermodynamic properties for solutions were compared with data reported in the literature. The present results are consistent with most previous reported thermodynamic data for the pure water and H2O + LiNO3 solutions at low temperatures. 相似文献
19.
J. F. A. Soltero J. E. Puig P. C. Schulz 《Journal of Thermal Analysis and Calorimetry》1998,51(1):105-114
The state of water and several transitions were examined in the systemsn-decanephosphonic acid (DPA)—water and the sodium salts of DPA—water. Temperature — composition phase diagrams are reported.
The results show that several liquid crystalline phases plus isotropic liquid, and two solid phases (a waxy solid phase and
a crystalline phase) are formed. Several types of water were detected: bulk-like water, interfacial water and hydration water.
This work was supported by the Consejo Nacional de Ciencia y Technología de México (grant # 3319-E) and by the Consejo Nacional
de Investigaciones Científicas y Técnicas de la República de Argentina. 相似文献
20.
Parimal C. Dey Muhammad A. Motin Tapan K. Biswas Entazul M. Huque 《Monatshefte für Chemie / Chemical Monthly》2003,134(6):797-809
Summary. The apparent molar volume (φv) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function
of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φv) of the carbohydrates was found to be a linear function of the concentration. From a φv versus molality (b) plot, the apparent molar volume at infinite dilution (), which is practically equal to the partial molar volume at infinite dilutions () of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG
≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf
Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more
structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of
solute–solvent interactions.
Corresponding author. E-mail: chemistry_ru@yahoo.com
Received March 19, 2002; accepted (revised) July 31, 2002
Published online February 24, 2003 相似文献