Physical Properties of Binary Liquid Systems: Ethanoic Acid/Propanoic Acid/Butanoic Acid with Cresols

Density, viscosity and surface tension of nine binary liquid systems: ethanoic acid, propanoic acid and butanoic acid with o-cresol, m-cresol and p-cresol have been determined at 298.15, 308.15 and 318.15 K over the complete compositional range. From the experimental results the excess values of molar volume (V ^E), viscosity (η ^E), Gibbs free energy for the activation of flow (ΔG ^E) and surface tension (σ ^E) were evaluated. The excess values were fitted to the Redlich–Kister type equation using a nonlinear regression technique. The Grunberg–Nissan parameter, d, was also calculated. From the sign and magnitude of the V ^E, η ^E, ΔG ^E, σ ^E, and d values, it is concluded that specific interactions are present in all of the nine binary mixtures under study. V ^E is negative for carboxylic acid–cresol mixtures at all temperatures and over the entire composition range. The values of η ^E, ΔG ^E and σ ^E are positive over the whole range of composition and increase with increasing temperature at a constant mole fraction of the carboxylic acid, confirming the existence of specific interactions in these binary mixtures. Further, the viscosity data of the binary systems were fitted to various theoretical/empirical models. The binary viscosity data is well represented by the Auslander model. Surface tension data were fitted to various theoretical/empirical models. The binary mixture surface tension data are well represented by the model given by Zihao and Jufu.     

Viscosities and Surface Tensions of Phenetole with <Emphasis Type="Italic">N</Emphasis>-Methyl-2-pyrrolidone, <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dimethylformamide and Tetrahydrofuran Binary Systems at Three Temperatures

Viscosities, η, and surface tensions, σ, of binary systems of phenetole (ethoxy benzene or ethyl phenyl ether) with N-methyl-2-pyrrolidone, N,N-dimethylformamide or with tetrahydrofuran were measured over the entire mole fraction range and at (298, 303 and 308) K. The experimental data was used to compute the deviations in viscosity, Δη, and surface tension, Δσ. Values of the excess Gibbs energy of activation G*^E, surface entropy S _σ and surface enthalpy H _σ were calculated. Viscosity data of the binary systems were calculated using the Grunberg and Nissan and the three-body and four-body McAllister correlations. The Redlich–Kister method was used for evaluation of coefficients and standard deviations for Δη, Δσ and G*^E. The results were interpreted in terms of the probable effect of molecular interactions between components as well as polarity.     

Excess thermodynamic functions derived from densities and surface tensions of (p- or o-xylene + ethylene glycol dimethyl ether) between the temperatures (298.15 and 308.15) K

Densities (ρ) for binary systems of (p-xylene or o-xylene + ethylene glycol dimethyl ether) were measured over the full mole fraction range at the temperatures of (298.15, 303.15 and 308.15) K along with the densities of the pure components. The excess molar volumes (V^E) calculated from the density data show that the deviations from ideal behaviour in the two binary systems are negative, and they become more negative with the temperature increasing. Surface tensions (σ) of these binary systems were determined at the same temperatures (298.15, 303.15 and 308.15) K by the pendant drop method. The surface tension deviations (δσ) for p-xylene system are negative over the whole composition range, and become less negative with the temperature increasing, but for the o-xylene system, δσ are negative at high o-xylene concentration, and change to positive with the o-xylene concentration decreasing. The V^E and δσ were fitted to the Redlich–Kister polynomial equation. Surface tensions were also used to estimate surface entropy (S_σ) and surface enthalpy (H_σ).     

Surface tension of binary and two ternary mixtures containing water–acetonitrile–methanol/ethanol at 298.15 K: experimental data,correlation and prediction by various models

Surface tension of two ternary mixtures of water/acetonitrile/methanol and water/acetonitrile/ethanol, and their constituent binaries, were measured over the whole range of composition at 298.15 K and ambient pressure. The experimental data were used to calculate in the surface tension deviations (Δσ). The negative values of Δσ for the binary and ternary systems indicate the strong hydrogen bonding between unlike molecules of mixtures (particularly in the high concentration of water). Surface tension data of the binary systems were correlated with Fu et al., Wang–Chen, Redlich–Kister and Myers–Scott models. The mean standard deviation obtained from the comparison of experimental and calculated surface tension values for binary systems with four models is less than 0.42. Finally, the concentration dependence of the surface tension deviation of the ternary mixtures at 298.15 K was correlated using Pando et al. and Ku et al. models, with satisfactory results.     

Anomalous thermal expansion of thin cetane layer solidified at the inner surface of confining nanoporous silica gel

Silica gel with extremely small pores of 3 nm diameter was filled with liquid cetane. Samples with various coefficients of filling k of cetane were prepared. After the solidification of confined cetane, its free volume has been investigated. The positron annihilation lifetime spectroscopy at 24–300 K and differential scanning calorimetry (DSC) at 233–303 K measurements have been performed. Decreasing the temperature, only small changes in dimensions of silica gel matrix and pronounced contraction of confined cetane have been indicated. In the case of k < 0.2, however, via cooling below 180 K, the temperature dependence changes its sign and the free volume in confined cetane increases. Decreasing the cetane content, the negative apparent expansion coefficient dramatically grows. This anomalous temperature dependence is interpreted by the cracking of thin layer of solid cetane which is in contact with the walls of silica gel pores.     

Thermodynamic studies of methylene blue adsorption onto Fe-doped sulfated titania

Adsorption equilibrium of methylene blue onto Fe-doped sulfated titania (FST) samples was studied at different temperatures (298, 303, and 308 K). Based on the wavelength scanning from 580 to 760 nm, the wavelength of maximum absorbance of methylene blue was determined to be 666 nm and the corresponding calibration curve can be described by the equation of A = 0.0068 + 0.1514C. The adsorption of methylene blue onto FST samples was conformed to the Langmuir isotherms. The absorption capacity of each FST sample for methylene blue increases with increasing temperature. The increase in the adsorption parameters (q _m, b, and K ₀) and the positive ΔH ^θ reveal the endothermic feature of this adsorption process. The negative ΔG ^θ shows the adsorption of methylene blue onto FST samples can be carried out spontaneously at the examined temperatures. Furthermore, with the calcination temperature increases, the variation in crystallization degree, the surface and the sulfur species will obviously influence the adsorption properties of FST samples and the thermodynamic parameters of this adsorption process.     

Densities,surface tensions,and derived surface thermodynamics properties of (trimethylbenzene + propyl acetate,or butyl acetate) from T = 298.15 K to 313.15 K

Densities (ρ) for binary systems of (1,2,4-trimethylbenzene, or 1,3,5-trimethylbenzene + propyl acetate, or butyl acetate) were determined at four temperatures (298.15, 303.15, 308.15, and 313.15) K over the full mole fraction range. The excess molar volumes (V^E) calculated from the density data show that the deviations from ideal behaviour in the systems (all being positive, excepting 1,2,4-trimethylbenzene + butyl acetate system) become more positive with the temperature increasing. Surface tensions (σ) of these binary systems were measured at the same temperatures (298.15, 303.15, 308.15, and 313.15) K by the pendant drop method, the surface tension deviations (δσ) for all system are negative, and decrease with the temperature increasing. The V^E and δσ are fitted to the Redlich–Kister polynomial equation. Surface tensions were also used to estimate surface entropy (S_σ) and surface enthalpy (H_σ).     

Properties of n-butylpyridinium nitrate ionic liquid and its binary mixtures with water

The density and surface tension of the pure ionic liquid n-butylpyridinium nitrate ([BuPy]NO₃) were determined at temperature range from T = (293.15 to 338.15) K. The coefficient of thermal expansion, molecular volume and lattice energy of [BuPy]NO₃ were calculated from the experimental values of density. The surface entropy and enthalpy of [BuPy]NO₃ were investigated. The IL studied show much lower surface enthalpy and lattice energy in comparison with fused salts. The densities and surface tensions of binary mixtures of [BuPy]NO₃ with water have been measured within the whole composition range at T = 298.15 K and atmospheric pressure. Excess molar volumes V^E and surface tension deviations δγ were then deduced from the experimental results as well as partial molar volumes and excess partial molar volumes. Excess molar volumes have a negative deviation from ideal behavior and the surface tension deviations are negative over the whole compositions range. V^E and δγ were correlated with suitable equation respectively.     

The surface tension of liquid copper

The surface tension of liquid copper of 99.999 mass per cent purity has been measured by the sessile drop method in the temperature range 1373 to 1861 K. The least-squares equation expressing the surface tension σ as a function of temperature T is:

$\text{σ(}\text{Cu}\text{)/}\text{mN m}{}^{\mathrm{?}}\text{= (1552±35) ? (0.176±0.023)T/}\text{K}$

The linear correlation of excess surface enthalpy $\text{H}{}^{\mathrm{\sigma }}\text{A}{}^{\mathrm{\sigma }}$ and excess surface entropy $\text{S}{}^{\mathrm{\sigma }}\text{A}{}^{\mathrm{\sigma }}$ per unit area among σ(T) from the literature is also demonstrated. Estimation of $\text{S}{}^{\mathrm{\sigma }}\text{A}{}^{\mathrm{\sigma }}$ via the statistical electron-gas theory of Zadumkin and Pugachewich yields an equation for the calculation of recommended values for the surface tension of molten copper as a function of temperature:

$\text{σ(}\text{Cu}\text{)/}\text{mN m}{}^{\mathrm{?}}\text{= 1497 ? 0.174(T/}\text{K}\text{)}$

.     

PVT,viscosity, and surface tension of ethanol: New measurements and literature data evaluation

In this work, the results of density, viscosity, and surface tension measurements for ethanol are presented. Ethanol with stated mass fraction purity greater than 0.998 was further purified using molecular sieves. Density was measured within the temperature and pressure ranges, respectively, T = (278.15 to 353.15) K and p = (0.1 to 35) MPa by means of a vibrating tube densimeter, model DMA 512P from Anton Paar with an estimated uncertainty of ±0.5 kg · m^?3. The experimental (p, ρ, T) results have been correlated by Tait equation. From this equation the isobaric expansivity, the isothermal compressibility, and the thermal pressure coefficient have been calculated. Viscosity was measured over the range T = (273.15 to 346.15) K using an Ubbelohde viscometer with a Schott–Geräte automatic measuring unit (Model AVS-470) with the associated uncertainty of ±0.001 mPa · s. The measured values were combined with selected values from the literature covering the range T = (223 K to 503) K, and the VTF model has been fitted to all the data. The surface tension of the liquid was measured using a tensiometer KSV Sigma 70 with a Du-Noüy ring for the range of T = (274.77 to 318.99) K with an uncertainty of ±0.01 mN · m^?1. Using these data and critically assessed data of other authors compiled from the literature, a form of the IAPWS equation was used to correlate the surface tension within the temperature range 223 K up to the critical temperature.     

Thermodynamic functions and structure of gallium + tellurium liquid alloys

In the frame of our systematic investigation on strongly interacting alloy systems, we have measured the molar enthalpy of formation, ΔH_f, of liquid Ga + Te alloy at 1200 and 1238 K by direct reaction calorimetry, using a Calvet microcalorimeter. The enthalpy of formation, with reference to the pure liquid components, is negative over the whole range of mole fractions x and has a minimum at x_Te ≈ 0.6. ΔH_f(l, x_Te = 0.61, 1200 K) = ?(38.8 ± 0.8) kJ mol^?1. This is evidence for strong chemical interactions in the liquid phase with formation of Ga₂Te₃ clusters. No significant difference was noted between the enthalpies at 1200 and 1238 K. Comparison of the molar integral enthalpies and entropies of formation of liquid Me_0.4^IIITe_0.6 alloys (Me^III  Al, Ga, In, and Tl) shows that the stability of the Me₂Te₃ clusters decreases in the series Al > Ga > In > Tl.     

Preparation and characterization of blended solid polymer electrolyte 49% poly(methyl methacrylate)-grafted natural rubber:poly(methyl methacrylate)–lithium tetrafluoroborate

The preparation and characterization of blended solid polymer electrolyte 49% poly(methyl methacrylate)-grafted natural rubber (MG49):poly(methyl methacrylate) (PMMA) (30:70) were carried out. The effect of lithium tetrafluoroborate (LiBF₄) concentration on the chemical interaction, structure, morphology, and room temperature conductivity of the electrolyte were investigated. The electrolyte samples with various weight percentages (wt.%) of LiBF₄ salt were prepared by solution casting technique and characterized by Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy. Infrared analysis demonstrated that the interaction between lithium ions and oxygen atoms occurred at symmetrical stretching of carbonyl (C=O) (1,735 cm^?1) and asymmetric deformation of (O–CH₃) (1,456 cm^?1) via the formation of coordinate bond on MMA structure in MG49 and PMMA. The reduction of MMA peaks intensity at the diffraction angle, 2θ of 29.5° and 39.5° was due to the increase in weight percent of LiBF₄. The complexation occurred between the salt and polymer host had been confirmed by the XRD analysis. The semi-crystalline phase of polymer host was found to reduce with the increase in salt content and confirmed by XRD analysis. Morphological studies by SEM showed that MG49 blended with PMMA was compatible. The addition of salt into the blend has changed the topological order of the polymer host from dark surface to brighter surface. The SEM analyses supported the enhancement of conductivity with the addition of salt. The conductivity increased drastically from 2.0 to 3.4?×?10^?5 S cm^?1 with the addition of 25 wt.% of salt. The increase in the conductivity was due to the increasing of the number of charge carriers in the electrolyte. The conductivity obeys Arrhenius equation in higher temperature region from 333 to 373 K with the pre-exponential factor σ _o of 1.21?×?10^?7 S cm^?1 and the activation energy E _a of 0.46 eV. The conductivity is not Arrhenian in lower temperature region from 303 to 323 K.     

Surface tension measurements with validated accuracy for four 1-alkyl-3-methylimidazolium based ionic liquids

Air–liquid interfacial surface tension measurements are reported on four 1-alkyl-3-methylimidazolium ([C_n-mim], n = 2, 4, 6) based ionic liquids at 15 temperatures from (283 to 353) K at atmospheric pressure. To validate the accuracy of the results, the Wilhelmy plate method and the du Noüy ring method were employed in parallel, using the Kr?ss K100MK2 tensiometer. At each temperature from 29 to 44 individual readings were taken. The surface tension average values at particular temperatures are presented with the estimated overall standard uncertainty ranging from (±0.025 to ±0.1) mN · m^?1. An empirical surface tension–temperature equation has been developed describing the temperature dependence of each ionic liquid surface tension. Some details of the measurement procedure that have been found to be important in achieving the highest possible accuracy are discussed.     

Removal of uranium(VI) from aqueous solutions using nanoporous ZnO prepared with microwave-assisted combustion synthesis

The adsorption of the uranyl ions from aqueous solutions on the nanoporous ZnO powders has been investigated under different experimental conditions. The adsorption of uranyl on nanoporous ZnO powders were examined as a function of the contact times, pH of the solution, concentration of uranium(VI) and temperature. The ability of this material to remove U(VI) from aqueous solution was followed by a series of Langmuir and Freunlinch adsorption isotherms. The adsorption percent and distribution coefficient for nanoporous ZnO powders were 98.65 % ± 1.05 and 7,304 mL g^?1, respectively. The optimum conditions were found as at pH 5.0, contact time 1 h, at 1/5 Zn²⁺/urea ratio, 50 ppm U(VI) concentration and 303 K. The monomolecular adsorption capacity of nanoporous ZnO powders for U(VI) was found to be 1,111 mg g^?1 at 303 K. Using the thermodynamic equilibrium constants obtained at different temperatures, various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, have been calculated. Thermodynamic parameters (ΔH° = 28.1 kJ mol ^?1, ΔS° = 160.30 J mol^?1 K^?1, ΔG° = ?48.54 kJ mol^?1) showed the endothermic and spontaneous of the process. The results suggested that nanoporous ZnO powders was suitable as sorbent material for recovery and adsorption of U(VI) ions from aqueous solutions.     

A theoretical study on the structure and hygroscopicity of ammonium dinitramide

Density functional theory (DFT) and the dispersion corrected DFT have been used to investigate the hygroscopicity of ammonium dinitramide (ADN). Calculation results show that the gaseous ADN has a strong hydrogen bond. But the ionic pair structure NH₄ ⁺ · N(NO₂)^? is stabilized upon the addition of water molecules. Natural bond orbital calculations suggest that the intra- and intermolecular orbital interactions LP(O) → σ*(N–H) or LP(O) → σ*(O–H) make the system stabilized as a whole. En energy decomposition analysis reveals that the interactions between ADN and H₂O are dominated by the electrostatic and orbital interactions. The formation reactions become more spontaneous with the increasing number of water molecules but can be weakened by the growing temperature from 200 to 400 K. Moreover, the molecular dynamic method is applied to explore a more realistic cluster model to study the interactions between ADN and H₂O.     

Line tension and its influence on droplets and particles at surfaces

In this review we examine the influence of the line tension τ on droplets and particles at surfaces. The line tension influences the nucleation behavior and contact angle of liquid droplets at both liquid and solid surfaces and alters the attachment energetics of solid particles to liquid surfaces. Many factors, occurring over a wide range of length scales, contribute to the line tension. On atomic scales, atomic rearrangements and reorientations of submolecular components give rise to an atomic line tension contribution τ_atom (～1 nN), which depends on the similarity/dissimilarity of the droplet/particle surface composition compared with the surface upon which it resides. At nanometer length scales, an integration over the van der Waals interfacial potential gives rise to a mesoscale contribution |τ_vdW| ～ 1–100 pN while, at millimeter length scales, the gravitational potential provides a gravitational contribution τ_grav ～ +1–10 μN. τ_grav is always positive, whereas, τ_vdW can have either sign. Near wetting, for very small contact angle droplets, a negative line tension may give rise to a contact line instability. We examine these and other issues in this review.     

Nitrite electrochemical sensor for food analysis based on direct immobilization of hemoglobin on multi-walled carbon nanotube ionic liquid electrode

A novel nitrite biosensor was constructed by simultaneous immobilization of hemoglobin (Hb) and a room temperature ionic liquid, octylpyridinium chloride ([OcPy][Cl]), on multi-walled carbon ionic liquid electrode (MWILE). The direct electron transfer of Hb showed a pair of redox peaks with a formal potential of ?0.187 V vs. Ag/AgCl in pH 5.0 acetate buffer solution. Nitrite (NO₂ ^?) catalysis on the modified electrode was investigated by cyclic voltammetry and amperometry. The biosensor exhibited a wide linear range for NO₂ ^? detection from 0.01 to 15 mM, with a detection limit (3σ) of 1.46 μM. MWILE provided an excellent matrix for protein immobilization and biosensor fabrication which could be used for the determination of NO₂ ^? with a low detection limit, fast response, long linearity, and excellent sensitivity.     

Proton-conducting membranes: poly (N-vinyl pyrrolidone) complexes with various ammonium salts

The present study focuses on the proton-conducting polymer electrolytes; poly (N-vinyl pyrrolidone)–ammonium thiocyanate and poly (N-vinyl pyrrolidone)–ammonium acetate prepared by solution casting technique. The XRD analysis indicates the amorphous nature of the polymer electrolytes. The Raman spectra of the C=O vibration of pure polymer PVP at 1,663 cm^?1 has been appeared as doublet in the polymer electrolytes. The introduction of this new peak in the salt-doped polymer electrolytes may be due to interaction of the cation with the polymer. The room temperature ionic conductivity σ _303κ has been found to be high, 1.7?×?10^?4 S cm^?1 for 80 mol% PVP–20 mol% NH₄SCN and 1.5?×?10^?6 S cm^?1 for 75 mol% PVP–25 mol% CH₃COONH₄. The polymer electrolytes have been tested for their application in Zn–air battery.     

Survismeter Unit for Surface Tension,Viscosity, and Dipole Moment Determination for Polystyrene Interactions in Benzene

Novel instrumental set up is developed for surface tension (γ, N m^?1), viscosity (η, N s m^?2)) and dipole moment (μ/Debye) measurements. A new instrument is economic, viable and pollution free in use, the γ, η and μ from viscosities (η, N s m^?2) and surface tension (γ, N m^?1) for 0.005 to 0.125 g% polystyrene at an interval of 0.0005 g% in benzene are measured at 288.15, 293.15, and 298.15 Kelvin temperatures. The γ, η, and μ are reported stronger frictional and cohesive forces due to stronger interactions of polystyrene with benzene. The survismeter is highly accurate and mechanically operated for pulling up liquid from reservoir bulb B1 to operational bulbs B2, B3, and B4. Densities are higher than those of benzene and also infer stronger polystyrene–benzene interactions, and hydrodynamic volume (HV) calculated with intrinsic viscosity [η] is noted in 293.15 (HV) >298.15 (HV) >288.15 (HV) order with higher values at 293.15 K. Surface tension (γ) values are slightly higher than of benzene and fall in a range of 33.47 to 33.35 N m^?1.