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1.
G. H. Zimmerman Philip W. Scott Wendy Greynolds Dmitriy Mayorov 《Journal of solution chemistry》2009,38(4):499-512
Electrical conductance measurements were made on dilute solutions of hydrochloric acid to 458 K and 1.4 MPa with a flow instrument.
These measurements agree well with those of previous authors. The conductance theory of Fuoss and Hsia as given by Fernandez-Prini
(FHFP), was fit to these measurements. It was found that this theory adequately described the present results with a single
parameter, the limiting conductance at infinite dilution Λ°(HCl). Within their estimated accuracy, reported literature results of Λ°(HCl) between 264.15 and 579 K and high pressures were found to be represented by a five-parameter equation that was a function
of the solvent viscosity, temperature and pressure. This equation along with the FHFP theory permits accurate calculation
of the conductance of dilute hydrochloric acid solutions at high temperatures and pressures.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
2.
Yonit Sembira-Nahum Alexander Apelblat Emanuel Manzurola 《Journal of solution chemistry》2008,37(3):391-401
Densities of aqueous solutions of L-glutamic acid and magnesium-L-glutamate were determined from T=288.15 to 333.15 K at 5 K temperature intervals. The measured densities were used to evaluate the apparent molar volumes,
V
2,φ
(m,T), the cubic expansion coefficients, α(m,T), and the changes of isobaric heat capacities with respect to pressure, (∂
C
p
/∂
p)
T,m
. They were qualitatively correlated with changes in the structure of water that occur when L-glutamic acid or magnesium-L-glutamate
are present. 相似文献
3.
A homopolymer of methyl methacrylate (MMA) and its copolymer with styrene at different compositions were synthesized and characterized.
Viscosity measurements of the synthesized homopolymer and the copolymers in toluene solutions were performed at 313 K. Different
equations were used to calculate the intrinsic viscosity, viscometric constants values, and molecular weight of the synthesized
polymers. The values of intrinsic viscosity and viscosity average molecular weight obtained by the two methods (single point
determination and graphical extrapolation) were compared in order to verify the validity of the single point determination
for the polymers. Viscometric properties derived included the specific viscosity (it determines the contribution of the solute
to the viscosity of the solution), the reduced viscosity (that provides a measure of the polymer capacity for increasing the
solution viscosity), and the intrinsic viscosity. 相似文献
4.
The effects of temperature and common ions on binding of puerarin to bovine serum albumin (BSA) are investigated. The binding
constants (K
a) between puerarin and BSA are 1.13×104 L⋅mol−1 (20 °C) and 1.54×104 L⋅mol−1 (30 °C), and the number of binding sites (n) is (0.95±0.02). However, at a higher temperature (40 °C) the stability of the puerarin–BSA system decreases, which results
in a lower binding constant (1.58×103 L⋅mol−1) and number of binding sites (n=0.73) of the puerarin–BSA system. However, the presence of Cu2+ and Fe3+ ions increases the binding constants and the number of binding sites in the puerarin–BSA complex. 相似文献
5.
Fluorescence emission spectroscopy have been used to investigate the effects of electrolytes on the excited state intramolecular
charge transfer (ICT) reaction in 4-(1-azetidinyl)benzonitrile (P4C) in very dilute to concentrated electrolyte solutions
of ethyl acetate (EA), acetonitrile (AN) and ethanol (EtOH). In the limit of very low electrolyte concentrations, the reaction
rate (=1/τ
rxn, τ
rxn being the reaction time) is found to decrease with increasing electrolyte concentration, the extent of decrease being the maximum in EA and the minimum in AN. At moderate
to higher electrolyte concentrations, however, the rate increases upon further addition of electrolyte. The observed non-monotonic
electrolyte concentration dependence of rate is believed to occur due to a novel interplay between friction and solvation
experienced by the photo-excited reactant in solution. Moreover, the long time decay constant and amplitude of the bi-exponential
decay of the time resolved fluorescence emission intensity also show a significant electrolyte concentration dependence which
corroborates the relevant steady-state results.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
6.
Raphael da C. Cruz Rosana J. Martins Márcio J. E. de M. Cardoso Oswaldo E. Barcia 《Journal of solution chemistry》2009,38(8):957-981
Density measurements were made for binary aqueous solutions of polyethylene glycol at seven temperatures: 283.15, 288.15,
293.15, 298.15, 303.15, 308.15, and 313.15 K. Polyethylene glycol samples with nominal average molar masses of 3000 g⋅mol−1 (PEG 3000), 6000 g⋅mol−1 (PEG 6000), 10000 g⋅mol−1 (PEG 10000) and 20000 g⋅mol−1 (PEG 20000) were used. These results were used to determine the specific volumes of solutions with solute-to-solvent mass
ratios (mass of the solute/mass of the solvent) in the range 0.0546 to 1.4932 for PEG 3000, from 0.0553 to 1.4986 for PEG
6000, from 0.0552 to 1.2241 for PEG 10000, and from 0.0530 to 1.2264 for PEG 20000. The differences between the specific volume
of a solution and the specific volume of the pure solvent, at a given temperature, were represented by a virial-type equation
in terms of solute concentration. The first-order coefficient of the expansion is the partial specific volume of the solute
at infinite dilution. The higher-order coefficients are related to the contribution of pairs, triplets, and higher-order solute
aggregates, according to the Constant-Pressure Solution Theory. The functional dependence of the virial coefficients upon
temperature is discussed in terms of solute-solute and solute-solvent interactions. The effect of the PEG molar mass on the
partial specific volume of solute at infinite dilution, as well as the contributions of pairs of solute molecules to the solution
volume, are also investigated. The apparent specific volume, apparent specific expansibility, apparent specific expansibility
at infinite dilution and virial coefficients of the apparent specific expansibility are also presented. 相似文献
7.
Kaiyu Zhao Long Li Jing Li Yafei Guo Yuanhui Liu Tianlong Deng 《Journal of solution chemistry》2018,47(5):827-837
Densities for aqueous solutions of magnesium tetraborate MgB4O7(aq) at the molalities of (0.00556–0.03341) mol·kg?1 were measured with an Anton Paar Digital vibrating-tube densimeter at temperature intervals of 5 K from 283.15 to 363.15 K and 0.1 MPa. Apparent molar volumes were obtained based on the experimental density data, and the 3D diagrams of the apparent molar volume (V ? ) of MgB4O7(aq) against temperature (T) and molality (m) were plotted. On the basis of the Vogel–Tamman–Fulcher equation, the coefficients of the correlation equation for densities of MgB4O7(aq) against temperature and molality were parameterized. According to the Pitzer ion-interaction model of the apparent molar volume, the temperature correlation equations of Pitzer single-salt parameters F(i,p,T)?=?a0?+?a1?×?T?+?a2?×?T 2?+?a3/T?+?a4?×?ln(T)?+?a5?×?T 3 (where T is temperature in Kelvin, a i are model parameters) for MgB4O7 were obtained for the first time. 相似文献
8.
Jaka Horvat Marija Bešter-Rogač Cveto Klofutar Darja Rudan-Tasic 《Journal of solution chemistry》2008,37(9):1329-1342
The viscosities of aqueous solutions of lithium, sodium, potassium, rubidium and caesium cyclohexylsulfamates were measured
at 293.15, 298.15, 303.15, 313.15 and 323.15 K. The relative viscosity data were analyzed and interpreted in terms of the
Kaminsky equation, η
r=1+Ac
1/2+Bc+Dc
2. The viscosity A-coefficient was calculated from the Falkenhagen-Dole theory. The viscosity B-coefficients are positive and relatively large. Their temperature coefficient ∂
B/∂
T is negative or near zero for lithium and sodium salts whereas for potassium, rubidium and caesium salts it is positive. The
viscosity D-coefficient is positive. This was explained by the size of the ions, structural solute–solute interactions, hydrodynamic
effect, and by higher terms of the long-range Debye-Hückel type of forces. From the viscosity B-coefficients the thermodynamic functions of activation of viscous flow were calculated. The limiting partial molar Gibbs
energy of activation of viscous flow of the solute was divided into contributions due to solvent molecules and the solute
in the transition state. The activation energy of the solvent molecules was calculated using the limiting Gibbs energy of
activation for the conductance of the solute ions. The activation energy of the solvent molecules was then discussed in terms
of the nature of the alkali-metal ions and their influence on the structure of water. The limiting activation entropy and
enthalpy of the solute for activation of viscous flow were interpreted by ion-solvent bond formation or breaking in the transition
state of the solvent. The hydration numbers of the investigated electrolytes were calculated from the specific viscosity of
the solutions. 相似文献
9.
Yu-Feng Hu Xiao-Ming Peng Chuan-Wei Jin Ying-Guo Liang Hong-Da Chu Xian-Ming Zhang 《Journal of solution chemistry》2010,39(11):1597-1608
Densities and electrical conductivities were measured for the ternary systems NaCl–mannitol(C6H14O6)–H2O, KCl–glycine(NH2CH2COOH)–H2O, KCl–mannitol–H2O, and NaBr–mannitol–H2O at 298.15 K. Densities of the binary systems KCl–H2O, NaBr–H2O, glycine–H2O and conductivities of the binary system NaBr–H2O at 298.15 K were also measured. The measured densities were used to check the predictions of the semi-ideal solution theory.
A new approach for predicting the conductivity of ternary electrolyte−nonelectrolyte mixture solutions in terms of the properties
of their binary solutions of equal water activity is presented and compared with the measured values. The results show that
the semi-ideal solution theory can provide good predictions for the densities and conductivities of the tested ternary electrolyte−nonelectrolyte
solutions from the properties of their binary subsystems. 相似文献
10.
M Köhnke S Schmitt N Ariotti AM Piggott RG Parton E Lacey RJ Capon K Alexandrov D Abankwa 《Chemistry & biology》2012,19(7):866-874
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11.
Solution densities over the temperature range 288.15 to 328.15 K have been measured for aqueous solutions of N-acetylarginamide monotrifluoroacetate and sodium trifluoroacetate, from which the partial molar volumes at infinite dilution,
V2oV_{2}^{\mathrm{o}}, were determined. The partial molar heat capacities at infinite dilution, Cp,2oC_{p,2}^{\mathrm{o}}, were also determined for these solutes over the same temperature range. These V2oV_{2}^{\mathrm{o}} and Cp,2oC_{p,2}^{\mathrm{o}} results, along with relevant data taken from the literature, have been used to calculate the contributions of the protonated
arginyl side-chain to the thermodynamic properties. These new side-chain values were critically compared with those obtained
previously using alternative side-chain model compounds. 相似文献
12.
Simultaneous measurements with magnesium ion-selective and pH glass electrodes have been used for determination of the stability
constants of magnesium ions with various biologically relevant ligands by alkalimetric titration under physiological conditions
(37 ○C, I=0.15 mol⋅dm−3). New systems were investigated: magnesium with pyroglutamate, pyridoxine and HEPES, along with citrate, lactate, glycinate,
aspartate and glutamate. For comparison, calcium stability constants with the same ligands were determined similarly, using
calcium ion-selective and pH glass electrodes. Ligand protonation constants, necessary for the calculation of the metal complex
formation constants, were also determined. 相似文献
13.
Júlia Ričanyová Renata Gadzała-Kopciuch Katarina Reiffova Yaroslav Bazel Bogusław Buszewski 《Adsorption》2010,16(4-5):473-483
The use of a novel procedure of solid-phase extraction with molecularly imprinted polymers (MISPE) has been described. A MISPE procedure relying on tailor-made, artificial-mimic materials capable of selectively rebinding target analytes (steroids) based on a combination of recognition mechanisms, such as size, shape and functionality, was custom designed for progesterone and testosterone. The combination of MISPE with LC/DAD is a simple and an efficient method for the determination and quality control of progesterone and testosterone in human urine samples. 相似文献
14.
Carmen M. Romero Luis C. Garzon Luis H. Blanco Andres F. Suarez 《Journal of solution chemistry》2014,43(6):1147-1155
The solubility of nitrogen and argon in aqueous solutions of dodecyltrimethylammonium bromide (DTAB) were measured, using the drop pressure method, at temperatures between (283.15 and 298.15) K and partial pressure of 101325 Pa of gas in an instrument specially developed for this purpose. The gas solubility was calculated as Henry’s constant. The solubilities of argon and of nitrogen increase linearly with DTAB concentration and decrease as the temperature increases. Experimental results show that the increase in the solubility of argon and nitrogen in the DTAB micelles is between 59.0 and 83.5 higher than the solubility in pure water, reflecting the ability of DTAB micelles to increase the solubility of non-polar gases in water. 相似文献
15.
16.
Complexes of copper(II) with a number of polyphosphate and polymetaphosphate anions have been studied in aqueous solutions
by potentiometric, spectroscopic and theoretical methods. Stability constants of the complexes have been determined as well
as their coordination modes. Results of the equilibrium studies provided evidence for the formation of ML, MHL and ML(OH)
x
type complexes with the ligands studied. The length of the polyphosphate chain was found to affect the oxygen atom charge
that is reflected in the stability constants of the ML type complexes. Moreover, the stability of the complex is also influenced
by the spatial arrangement of the phosphate groups in phosphates and metaphosphates. The spectral parameters observed for
certain complexes have permitted us to deduce the inner coordination sphere of the studied complexes. 相似文献
17.
Density, speed of sound and refractive index of the imidazolium-based ionic liquids (ILs), 1-methyl-3-octylimidazolium chloride
[C8mim][Cl], 1-butyl-3-methylimidazolium methyl sulfate [C4mim][C1OSO3], and 1-butyl-3-methylimidazolium octyl sulfate [C4mim][C8OSO3], have been measured in the temperature range from 283.15 to 343.15 K. Experimental density and speed of sound have been
used to calculate the internal pressure p
i of the ILs. The p
i values were found to be higher than those of water and molecular organic liquids, but lower than those of classical molten
salts. We also calculated molar refraction R
M from the measured refractive index n
D in the temperature range from 288.15 to 343.15 K. Refractive indices of ILs were also higher than those of normal organic
liquids, but comparable to long-chain hydrocarbon organic solvents. The structure-property correlation of the ILs has been
discussed and the results have been compared to our earlier studies (Kumar in J. Solution Chem. 37:203–214, 2008). 相似文献
18.
The disaccharide isomaltose is produced via an enzymatic reaction and is adsorbed to BEA zeolite. This reaction integrated
adsorption can be achieved as fluidized bed as well as fixed bed. We investigated isotherms, adsorption enthalpies and sorption
kinetics of BEA zeolite and extrudates with a novel aluminum phosphate sintermatrix. These extrudates contain 50% (w/w) of
BEA 150 zeolites (Si/Al = 75) as primary crystals. BET-surface for extrudates is 245 m2⋅g−1 and 487 m2⋅g−1 for zeolite. Extrudates show a monomodal macropore structure with a maximum at 90 nm. All isotherms show a type I shape.
For lower equilibrium concentrations, which occur during the enzymatic reaction, Henry’s law is applied and compared to a
Langmuir model. Adsorption equilibrium constant K
i,L
calculated from Langmuir for extrudates at 4 °C is 64.7 mL⋅g−1 and more than twice as high as obtained from Henry’s law with K
i
is 26.8 mL⋅g−1. Adsorption on extrudates at 4 °C is much stronger than on zeolite crystals where the Henry coefficient K
i
is 17.1 mL⋅g−1. Adsorption enthalpy Δh
Ad calculated from van’t Hoff plot with the Henry equation is −44.3 kJ⋅mol−1 for extrudates and −29.6 kJ⋅mol−1 for zeolite crystals. Finally, the kinetics for ad- and desorption were calculated from the initial slope. The diffusion
rate for ad- and desorption on extrudates were in the same range while adsorption on zeolites is three orders of magnitudes
faster than desorption. 相似文献
19.
Pasquale Crea Concetta De Stefano Mutsa Kambarami Frank J. Millero Virender K. Sharma 《Journal of solution chemistry》2008,37(9):1245-1259
The protonation constants for oxidized glutathione, H
i−1L(4−i+1)−, K
i
H=[H
i
L(4−i)−]/[H
i−1L(4−i+1)−][H+] i=1,2,…,6 have been measured at 5, 25 and 45 °C as a function of the ionic strength (0.1 to 5.4 mol⋅[kg(H2O)]−1) in NaCl solutions. The effect of ionic strength on the measured protonation constants has been used to determine the thermodynamic
values (K
i
H0) and the enthalpy (ΔH
i
) for the dissociation reaction using the SIT model and Pitzer equations. The SIT (ε) and Pitzer parameters (β
(0), β
(1) and C) for the dissociation products (L4−, HL3−, H2L2−, H3L−, H4L, H5L+, H6L2+) have been determined as a function of temperature. These results can be used to examine the effect of ionic strength and
temperature on glutathione in aqueous solutions with NaCl as the major component (body fluids, seawater and brines). 相似文献
20.
Ertha Janine Lacerda de Medeiros Rita de Cássia Ramos do Egypto Queiroga Antônio Gouveia de Souza Angela Maria Tribuzy de M. Cordeiro Ariosvaldo Nunes de Medeiros Darklê Luiza de Souza Marta Suely Madruga 《Journal of Thermal Analysis and Calorimetry》2013,112(3):1515-1521
Dairies add fat supplements to the diets of small ruminants to increase energy production and consequently the production and quality nutritional and sensorial of the milk. This study investigated the thermal and oxidative stability of babassu, castor, faveleira, and sesame oils by TG/DTA and PDSC. The profile of the fatty oils studied was determined by GC–MS as well as physicochemical characteristics. The thermogravimetric profile of the oils indicated that mass loss was caused by the decomposition or volatility of the triacylglycerides. Faveleira and sesame oils showed a high percentage of polyunsaturated fatty acids, especially C18:2. From a nutritional standpoint, unsaturated oils are more suitable supplements for animals because they promote biochemical changes beneficial to human health. 相似文献