不同温度下氨基酸在α-咖啡碱水溶液中的体积、粘度及折光率特性

Measurements of density(ρ), viscosity(η), and refractive index(n), were carried out on α-amino acids, DL-solution at 298.15, 303.15, 308.15, and 313.15 K. These measurements have been carried out to evaluate some important parameters, viz., apparent molar volume (φv), partial molar volume (φv0), transfer volume (φ0v (tr)), viscosity A and B coefficients of Jones-Dole equation, free energies of activation per mole of solvent (△μ0#1) and solute (△μ0#2),enthalpies (△H*) and entropies (△S*) of activation of viscous flow, variation of B with temperature ((a)B/(a)T)P, and molar refractive index (RD). These parameters have been interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.     

Physicochemical Properties of Amino Acids in AqueousCaffeine Solution at 25, 30, 35 and 40 ℃

Density, viscosity, and refractive index, for glycine, DL-alanine, L-serine and DL-valine have been determined in aqueous solution of 0.05 mol/kg caffeine as a function of amino acid （AA） concentration at 25, 30, 35, and 40 ℃ The density data have been used to compute apparent molar volume. The partial molar volume （limiting apparent molar volume） was obtained by applying the Masson＇s equation. The viscosity data have been analyzed by means of Jones-Dole equation. The values of Falkenhagen coefficient and Jones-Dole coefficient thus obtained are used to interpret the solute-solute and solute-solvent interactions, respectively. Hydration number was also computed. The transition-state theory was applied to obtain the activation parameters of viscous flow, i.e., free energy of activation per mole of solvent, and solute. The enthalpy and entropy of activation of viscous flow were computed for the system. Refractive index was used to calculate molar refractivity of the mixtures. The results have been interpreted in the light of various interactions occurring between the components of the mixtures under applied experimental conditions.     

不同温度下α-氨基酸在CTAB溶液中的体积及折光率的变化

Densities(ρ)and refractive indices(nD)of glycine(Gly),DL-alanine(Ala),DL-valine(Val)(0.02,0.04,0.06,0.08,and 0.10 mol·L-1)in 0.005 and 0.008 mol·L-1 aqueous cetyltrimethylammonium bromide(CTAB)have been measured at 298.15,303.15,308.15,and 313.15 K.The density data have been utilized to calculate apparent molar volumes(φv),partial molar volumes(φ0v),at infinite dilution and partial molar volumes of transfer φ0v(tr)of amino acids.The refractive index data have been used to calculate molar refractivity(RD)of amino acids in aqueous cetyltrimethylammonium bromide.It has been observed that φ0v varies linearly with increasing number of carbon atoms in the alkyl chain of amino acids,and hence,was split to get contributions from the zwitterionic end groups(NH 3,COO-)and methylene group(CH2)of the amino acids.The behaviour of these parameters has been used to investigate the solute-solute,solute-solvent interactions and the effect of cetyltrimethylammonium cation on these interactions.     

Densities,Ultrasonic Speeds,Viscosities and Refractive Indices of Binary Mixtures of Benzene with Benzyl Alcohol,Benzonitrile, Benzoyl Chloride and Chlorobenzene at 303.15 K

Densities,ρ, ultrasonic speeds, u, viscosities,η, and refractive indices, n, of pure benzene, benzyl alcohol (BA), benzonitrile (BN), benzoyl chloride (BC), chlorobenzene (CB) and their thirty six binary mixtures, with benzene as common component, were measured at 303.15 K over the entire mole fraction range. From these experimental data the values of deviations in ultrasonic speed, △u, isentropic compressibility, △k_s,excess acoustic impedance, Z^E, deviation in viscosity, Dh, and excess Gibbs free energy of activation of viscous flow, G^*E, and partial molar isentropic compressibility, Kφ,2⁰ of BA, BN, BC and CB in benzene were computed. The variation of these derived functions with composition of the mixtures suggested the increased cohesion (molecular order) in the solution and that interaction (A-B)＞(A-A) or (B-B).Moreover, theoretical prediction of ultrasonic speed, viscosity and refractive index of all the four binary mixtures was made on the basis of empirical and semi-empirical relations by using the experimental values of the pure components. Comparison of theoretical results with the experimental values was made in order to assess the suitability of these relations in reproducing the experimental values of u, η and n. Also, molecular radii of pure liquids and the average molecular radii of binary mixtures were evaluated using the corresponding refractive indices of pure liquids and binary mixtures. The average molecular radii of binary mixtures were found to be additive with respect to mole fraction of the pure component.     

苯乙烯与邻、间、对-二甲苯二元混合液的分子间相互作用

The densities (ρ), ultrasonic speeds (v), and refractive indices (n) of binary mixtures of styrene (STY)with m-, o-, or p-xylene, including those of their pure liquids, were measured over the entire composition range at the temperatures 298.15, 303.15, 308.15, and 313.15 K. The excess volumes (VE), deviations in isentropic compressibilities(△ks), acoustic impedances (△Z), and refractive indices (△n) were calculated from the experimental data. Partial molar volumes (V0φ,2) and partial molar isentropic compressibilities (K0φ,2) of xylenes in styrene have also been calculated. The derived functions, namely, VE, △ks, △Z, △n, V0φ,2, and K0φ,2 were used to have a better understanding of the intermolecular interactions occurring between the component molecules of the present liquid mixtures. The variations of these parameters suggest that the interactions between styrene and o-, m-, or p-xylene molecules follow the sequences: p-xylene＞o-xylene＞m-xylene. Apart from using density data for the calculation of VE, excess molar volumes were also estimated using refractive index data. Furthermore, several refractive index mixing rules have been used to estimate the refractive indices of the studied liquid mixtures theoretically. Overall, the computed and measured data were interpreted in terms of interactions between the mixing components.     

Analysis of viscosity abnormalities of polyelectrolytes in dilute solutions

It was found that the interface effects in viscous capillary flow influenced the process of viscosity measurement greatly,and the abnormal viscosity behaviors of polyelectrolytes as well as neutral polymers in dilute solution region were ascribed to interface effect.According to this theory,we have reviewed the previous viscosity data of derivatives of poly-2- vinylpyridine reported by Maclay and Fuoss first.Then,the abnormal viscosity behaviors of a series of sodium polystyrene sulfonate samples with various molecular weights in dilute aqueous solutions were studied further.The solute adsorption behaviors and structural information of polymers have been discussed carefully.     

Volumetric and Refractive Index Behaviour of α-Amino Acids in Aqueous CTAB at Different Temperatures

Densities （ρ） and refractive indices （nD） of glycine （Gly）, DL-alanine （Ala）, DL-valine （Val） （0.02, 0.04, 0.06, 0.08, and 0.10 mol·L^-1） in 0.005 and 0.008 mol·L^-1 aqueous cetyltrimethylammonium bromide （CTAB） have been measured at 298.15, 303.15, 308.15, and 313.15 K. The density data have been utilized to calculate apparent molar volumes （φv）, partial molar volumes （φv^0）, at infinite dilution and partial molar volumes of transfer φv^0 （tr） of amino acids. The refractive index data have been used to calculate molar refractivity （Rr,） of amino acids in aqueous cetyltrimethylammonium bromide. It has been observed that φv^0 varies linearly with increasing number of carbon atoms in the alkyl chain of amino acids, and hence, was split to get contributions from the zwitterionic end groups （NH3^＋ COO^-） and methylene group （CH2） of the amino acids. The behaviour of these parameters has been used to investigate the solute-solute, solute-solvent interactions and the effect of cetyltrimethylammoniuln cation on these interactions,     

EFFECT OF THE COMPOSITION OF m-CRESOL/H2O SOLVENT ON HYDRODYNAMIC PROPERTIES OF NYLON 6

The intrinsic viscosity [ η], Huggins constant (KH), [ η]0, α3 and flow activation energy values of nylon 6 have been measured in water/m-cresol (0/100-20/80) systems at different temperatures (20-60℃). It has been found that the intrinsic viscosity, [η]0 and α3 increase with the increase in water contents in m-cresol up to 15% and then decrease. They increase with the increase in temperature irrespective of solvent composition. It has been noted that the percent increase of α3 is the highest at 60℃ and the lowest at 20℃ for a particular solvent system. The intrinsic viscosity data obey Arrhenius equation over the considered conditions. The activation energy and the KH values decrease very sharply with the addition of water,giving a minimum value at 15% of water and then increase slowly. The variation of all the parameters has been explained in terms of variation in thermodynamic quality of solvent with the addition of water to m-cresol and change in temperature,resulting in the change of conformational and orientational properties of polymer molecules. This change of solvent quality also results in variation of selective sorption of solvent over the polymer, such as hydrogen bonding, etc.     

Density of supercritical CO_2-tetrahydrofuran binary mixture and the partial molar volume of the cosolvent

The densities of supercritical CO2-tetrahydrofuran (cosolvent) binary mixture weremeasured at temperatures in range of 308.15 to 323.15 K and at pressure up to 16.5 MPa.The concentrations of tetrahydrofuran were from 0 to 0.57 mol/L.The partial molar volume of tetrahydrofuran was calculated based on the relationship between the density of the mixture and the concentration of the cosolvent.It is observed that the partial molar volume of the cosolvent is negative and the absolute value decreases with increasing pressure and the concentration of the cosolvent.     

Density, Viscosity, Refractive Index, and Speed of Sound in Binary Mixtures of Pyridine and 1-Alkanols (C6, C7, C8, C10) at 303.15 K

The densities (ρ), viscosities (η), refractive indices (nD), and speeds of sound (u), of binary mixtures of pyridine with 1-hexanol, 1-heptanol, 1-octanol and 1-decanol, including those of pure liquids, were measured over the entire composition range at 303.15 K and atmospheric pressure. From these experimental data, the values of excess molar volumes (VE), deviations in isentropic compressibilities (Δks), viscosities (Δh), molar refractions (ΔRm), apparent and partial molar volumes (Vf,2 and ), apparent and partial molar compressibilities (Kf,2 and ), of alkanols in pyridine and their corresponding deviations (ΔV and ΔK) were calculated. The variations of these parameters with composition of the mixtures suggest that the strength of interactions in these mixtures follow the order: 1-hexanol＞1-heptanol＞1-octanol＞1-decanol. All the excess and deviation functions were fitted to Redlich-Kister polynomial equation to determine the fitting coefficients and the standard deviations.     

不同温度下α-氨基酸在咖啡碱水溶液中的体积、粘度及折光率特性

Measurements of density(ρ), viscosity(η), and refractive index(n), were carried out on α-amino acids, DL-solution at 298.15, 303.15, 308.15, and 313.15 K. These measurements have been carried out to evaluate some important parameters, viz., apparent molar volume (φv), partial molar volume (φv0), transfer volume (φ0v (tr)), viscosity A and B coefficients of Jones-Dole equation, free energies of activation per mole of solvent (△μ0#1) and solute (△μ0#2),enthalpies (△H*) and entropies (△S*) of activation of viscous flow, variation of B with temperature ((a)B/(a)T)P, and molar refractive index (RD). These parameters have been interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.     

Interactions of Proline in Non-aqueous Anionic, Cationic and Nonionic Surfactants at Different Temperatures

Density and viscosity data of proline (Pro) in sodium dodecyl sulfate/cetyltrimethylammonium bromide/poly (oxyethylene) isooctyl phenyl ether in formamide were measured at 298.15, 303.15, 308.15, and 313.15 K and 0.1 MPa. The density data were utilized to evaluate standard partial molar volumes ( ) and partial molar isobaric expansibility ( ). The viscosity data were used to evaluate A- and B-coefficients, free energy of activation of viscous flow ( ) and ( ), per mole of solvent and solute respectively, enthalpy (ΔH^*) and entropy (ΔS^*) of activation of viscous flow. The results obtained were utilized in the qualitative elucidation of the Pro-surfactant/formamide and Pro-Pro interactions in the present systems.     

Study of molecular interactions in binary mixtures of formamide with 2-methoxyethanol and 2-ethoxyethanol at varying temperatures

The thermophysical properties of binary mixtures of formamide with 2-methoxyethanol and 2-ethoxyethanol have been investigated in this article. Densities, refractive index, ultrasonic velocity and viscosity for the two binary mixtures viz. formamide with 2-methoxyethanol and 2-ethoxyethanol have been measured over the entire composition range at 293, 303 and 313 K and at atmospheric pressure. The excess molar volume, the molar refraction deviation, excess Gibb's free energy of activation for viscous flow, excess isentropic compressibility, deviation in viscosity, excess free volume and excess molar enthalpy have been computed using experimental data. These excess parameters have been correlated with Redlich–Kister polynomial equation. The results have been interpreted on the basis of strength of intermolecular interaction occurring in these mixtures. Densities, refractive index and ultrasonic velocity were correlated with second-order polynomial equation. The molar volume and excess partial molar volume at infinite dilution have also been calculated for both the mixtures.     

Derived partial molar properties investigations of viscosity Arrhenius parameters in formamide + N,N-dimethylacetamide systems at different temperatures

Excess properties calculated from the literature values of experimental density and viscosity in N,N-dimethylacetamide + formamide binary mixtures between 298.15 K and 318.15 K can lead us to test different correlation equations as well as their corresponding relative functions. Inspection of the Arrhenius activation energy Ea and the enthalpy of activation of viscous flow ΔH* shows very close values. Here, we can define partial molar activation energies Ea₁ and Ea₂ for N,N-dimethylacetamide and formamide, respectively, along with their individual contribution separately. Correlation between the two Arrhenius parameters of viscosity in all compositions shows the existence of two main distinct behaviours separated by the mole fraction equal to 0.3 of N,N-dimethylacetamide. In addition, the correlation between Arrhenius parameters reveals interesting Arrhenius temperature, which is closely related to the vaporisation temperature in the liquid vapour equilibrium and the limiting corresponding partial molar properties can permit us to predict the boiling points of the pure components.     

Thermodynamic characteristics of solution and viscous flow of amino acids in water at 298.15 K

Thermodynamic and transport properties of aqueous solutions of 13 amino acids at 298.15 K are analyzed in relation to the structure of the side chains of the biomolecules on the basis of the newly obtained and published data. The standard enthalpies of solution (Δ_sol H ⁰), partial molar volumes (V _2,φ ⁰ ), and partial molar contributions to the molar Gibbs free energy of activation of the viscous flow (Δμ ₂ ^0≠ ) were determined for the amino acids in water. Correlation equations were suggested to describe the relationship between the enthalpy characteristics of hydration of amino acids, viscous flow parameters, and bulk properties of their aqueous solutions.     

Excess properties and spectroscopic studies of binary system 1,4-butanediol + water at T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K

Density and dynamic viscosity data were measured over the whole concentration range for the binary system 1,4-butanediol (1) + water (2) at T = (293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K as a function of composition under atmospheric pressure. Based on density and dynamic viscosity data, excess molar density (ρ^E), dynamic viscosity deviation (Δν) and excess molar volume (V_m^E) were calculated. From the dynamic viscosity data, excess Gibbs energies (ΔG*^E), Gibbs free energy of activation of viscous flow (ΔG*), enthalpy of activation for viscous flow (ΔH*) and entropy of activation for viscous flow (ΔS*) were also calculated. The ρ^E, V_m^E, Δν and ΔG*^E values were correlated by a Redlich?Kister-type function to obtain the coefficients and to estimate the standard deviations between the experimental and calculated quantities. Based on FTIR and UV spectral results, the intermolecular interaction of 1,4-butanediol with H₂O was discussed.     

Estimation of boiling points by investigations of viscosity Arrhenius behaviours in Methyl Benzoate + n-Hexane binary liquid systems at atmospheric pressure

Calculation of excess properties in methyl benzoate + n-Hexane binary liquid mixtures at (303.15, 308.15 and 313.15) K from experimental viscosity and density values was presented in earlier work. Investigations of these experimental values to test correlation quality of different equations as well as their corresponding relative functions were also reported. Considering the quasi-equality between the enthalpy of activation of viscous flow ΔH* and the viscosity Arrhenius activation energy Ea, here we can define partial molar activation energy Ea₁ and Ea₂ for methyl benzoate with n-Hexane, respectively, along with their individual contribution separately. Correlation between Arrhenius parameters brings to light interesting Arrhenius temperature with a comparison to the temperature of vaporisation in the liquid vapour equilibrium, and the limiting corresponding partial molar properties that can permit us to predict value of the boiling points of the pure components. New empirical equations for estimating the boiling temperature are proposed.     

Physical–chemical properties of nickel analogs ionic liquid based on choline chloride

In this paper, a homogeneous, green analogs ionic liquid containing choline chloride and nickel chloride hexahydrate is formed. The structure of the analogs ionic liquid is preliminary investigated by Fourier transform infrared spectroscopy. It is shown that the nickel chloride hexahydrate bond via hydrogen bonds with choline chloride and urea. The physico-chemical properties of the analogs ionic liquid such as viscosity, conductivity, density, and thermal stability are measured as a function of temperature and composition. The thermal expansion coefficients (r), the molar Gibbs energy of activation (ΔG*) for viscous flow, the molar enthalpy of activation (ΔH*), and the molar entropy of activation (ΔS*) for viscous flow have been calculated. A straight-line equation is used to fit the density data while the Arrhenius equation is used to fit both viscosity and conductivity. Thermal stability of analogs ionic liquid was carried out from room temperature to 973.15 K. It indicates that analogs ionic liquid is stable from room temperature to 488.2 K.