Density, viscosity, and excess properties of the binary mixture of diethylene glycol monomethyl ether + water at T = (293.15, 303.15, 313.15, 323.15, 333.15) K under atmospheric pressure

Densities and viscosities have been measured as a function of composition for the binary liquid mixture of diethylene glycol monomethyl ether CH₃O(CH₂)₂O(CH₂)₂OH + water at T = (293.15, 303.15, 313.15, 323.15, 333.15) K under atmospheric pressure. Densities were determined using a capillary pycnometer. Viscosities were measured with Ubbelohde capillary viscometer. From the experimental data, the excess molar volumes V^E, and viscosity deviations δη, and the excess energies of activation for viscous flow ΔG^*E were calculated. These data have been correlated by the Redlich–Kister type equations to obtain their coefficients and standard deviations. The results suggest that molecular interaction between diethylene glycol monomethyl ether and water is strong.     

Density, viscosity and ultrasonic velocity studies of aqueous solutions of sodium acetate at different temperatures

The densities and viscosities of aqueous solutions of sodium acetate have been measured at 298.15, 303.15, 308.15 and 313.15 K and at atmospheric pressure. The molality range has been studied between 6.09 × 10^− 2 to 7.314 × 10^− 1 mol kg^− 1. The experimental values of density have been used to calculate apparent molar volume, partial molar volume, solute–solute interaction parameter, and Hepler's constant. The viscosity data have been analyzed with Jone–Dole equation. Furthermore, ultrasonic velocity measurements of aqueous solutions of sodium acetate have been made at 298.15 and 308.15 K and at atmospheric pressure. From experimental values of ultrasonic velocity, apparent molar isentropic compressibility and limiting apparent molar isentropic compressibility have been calculated. All the parameters calculated from density, viscosity, and ultrasonic velocity indicate that the sodium acetate is water structure maker.     

Volumetric properties and viscosities of the 2-pyrrolidone + 1,2-propanediol + water ternary system and its binary constituents at T = 313.15 K

Densities and viscosities of ternary mixtures of 2-pyrrolidone + 1,2-propanediol + water and corresponding binary mixtures of 1,2-propanediol + water, 2-pyrrolidone + water and 2-pyrrolidone + 1,2-propanediol have been measured over the whole composition range at 313.15 K. From the obtained data, the excess molar volumes (V^E), the deviations in viscosity (Δη) and the excess Gibbs free energy of activation (ΔG^?E) have been calculated. The V^E, Δη and ΔG^?E results were correlated and fitted by the Redlich–Kister equation for binary mixtures and by the Cibulka equation for ternary mixtures, as a function of mole fraction. Several predictive empirical relations were applied to predict the excess molar volumes of ternary mixtures from the binary mixing data.     

Experimental viscosities and viscosity predictions of a ternary mixture comprising silicone oils and 1-octene from 293.15 K to 353.15 K

Viscosities of the ternary and binary mixtures of 1-octene, Rhodorsil H68, Rhodorsil 308V750 have been measured at different temperatures between 293.15 and 353.15 K and at atmospheric pressure. Two correlations were established to predict the viscosity of all mixtures. The first is a statistical expression deduced from an experimental design. The second is based on an additivity law and the temperature effect on binary mixtures.     

Thermophysical properties of binary mixtures (dimethyl carbonate + ketones) at T = (303.15, 308.15 and 313.15) K

The densities ρ, viscosities η, and refractive indices n_D of binary mixtures of dimethyl carbonate (DMC) with acetophenone, cyclopentanone, cyclohexanone, and 3-pentanone have been measured over the entire range of composition at the temperatures 303.15, 308.15 and 313.15 K and at atmospheric pressure. The density values were used to calculate excess molar volumes V^E, and other excess functions of interest such as deviations in viscosity Δη, excess Gibb's free energies of activation of viscous flow ΔG^E and deviations in molar refraction ΔR. The measured viscosities were compared with those predicted using the Grunberg-Nissan, Eyring-Margules, Soliman-Marshall, and McAllister four body models. Furthermore the refractive indices data have been correlated using Lorentz-Lorentz, Weiner, Newton, Gladstone-Dale, Eykman, and Eyring-John equations and a satisfactory agreement was found for all the binary systems studied in the present work.     

Densities, excess molar volumes, and viscosities of the binary and ternary mixtures of {diethylcarbonate (1) + p-chloroacetophenone (2) + 1-hexanol (3)} at 303.15 K for the liquid region and at ambient pressure

Densities ρ, dynamic viscosities η, of the ternary mixture (diethylcarbonate + p-chloroacetophenone + 1-hexanol) and the involved binary mixtures (diethylcarbonate + p-chloroacetophenone), (diethylcarbonate + 1-hexanol), and (p-chloroacetophenone + 1-hexanol) have been measured over the whole composition range at 303.15 K for the liquid region and at ambient pressure. The data obtained are used to calculate excess molar volumes V_m^E, excess partial molar volumes V¯_m,i^E, limiting excess partial molar volumes V¯_m,i^E,∞, and viscosity deviations Δη, of the binary and ternary mixtures. The data of excess molar volumes of the binary systems were fitted to the Redlich–Kister equation while for the ternary system the Cibulka equation was used. The McAllister's four body, and Kalidas and Laddha interaction models are used to correlate the kinematic viscosities of binary and ternary mixtures, respectively, to determine the fitting parameters and the standard deviations. The experimental data of the constitute binaries and ternary are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.     

Thermodynamics of mixtures containing alkoxyethanols. Part XXV. Densities, excess molar volumes and speeds of sound at 293.15, 298.15 and 303.15 K, and isothermal compressibilities at 298.15 K for 2-alkoxyethanol + 1-butanol systems

Densities, ρ, and speeds of sound, u, of systems formed by 2-methoxyethanol (2ME), 2-ethoxyethanol (2EE), 2-propoxyethanol (2PE), or 2-butoxyethanol (2BE) and 1-butanol have been measured at 293.15, 298.15 and 303.15 K and atmospheric pressure using a vibrating tube densimeter and sound analyser Anton Paar model DSA-5000. The ρ and u values were used to calculate excess molar volumes, V^E, at those temperatures and deviations from the ideal behaviour of the thermal expansion coefficient, Δ_P, or of the isentropic and isothermal compressibilities, Δκ_S and Δκ_T at 298.15 K. From the data, it is apparent that the interactional contribution to V^E is more important for systems with 2ME or 2EE, while structural effects are more relevant in the 2PE or 2BE mixtures, and that dipolar interactions decrease with the size of the 2-alkoxyethanol. Several methods are applied to predict speeds of sound: free length theory (FLT), collision factor theory (CFT), and Nomoto, Junjie and Van Dael equations. CFT and Nomoto's equation provide the better predictions. Finally, 1-butanol + 2-alkoxyethanol, or + 2-(2-alkoxyethoxy)ethanol mixtures have been studied using ERAS. Poorer results were obtained for systems including 2-(2-alkoxyethoxy)ethanols, which may be due to dipolar interactions and structural effects are more important in such solutions.     

Thermodynamic and structural properties of binary mixtures of some glycols with 2-butoxyethanol at T = (293.15, 298.15 and 303.15) K

Densities and relative permittivities at T = (293.15, 298.15, and 303.15) K in the binary mixtures of 2-butoxyethanol with ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol have been measured as a function of composition. From the experimental data excess molar volumes and deviations in relative permittivity have been calculated over the entire composition range. Both excess molar volumes and relative permittivity deviations have been correlated using Redlich–Kister type polynomial equation by the method of least-squares for the estimation of the binary coefficients and the standard errors. The experimental and calculated quantities were used to analyze the mixing behaviour of the components.     

Electrical conductances of sodium bromide and sodium tetraphenylborate in 2-ethoxyethanol + water mixtures at 308.15, 313.15, 318.15 and 323.15 K

The electrical conductances of the solutions of sodium bromide (NaBr) and sodium tetraphenylborate (NaBPh₄) in 2-ethoxyethanol + water mixed solvent media containing 0.25, 0.50 and 0.75 mass fractions of 2-ethoxyethanol (w₁) have been reported at 308.15, 313.15, 318.15, and 323.15 K. The conductance data have been analyzed by the 1978 Fuoss conductance–concentration equation in terms of the limiting molar conductance (Λ⁰), the association constant (K_A) and the association diameter (R). Of the two electrolytes investigated here, sodium bromide exists essentially in the form of free ions in aqueous 2-ethoxyethanol solutions over the entire temperature range investigated. However, slight ionic association was observed for sodium tetraphenylborate—the extent of which increases with increasing amount of 2-ethoxyethanol in the present mixed solvent media. The solvations of the bromide ion and of the sodium ion were found to be gradually weakened as the 2-ethoxyethanol content of the medium increases. Furthermore, the limiting molar conductivity values of the two electrolytes increase as the temperature increases in all 2-ethoxyethanol + water mixtures which have been described by polynomial equations.     

Atomic and electronic structure of group-IV adsorbates on the GaAs(0 0 1)-(1 × 2) surface

Ab initio calculations, based on pseudopotentials and density functional theory, have been performed to investigate the atomic and electronic structure of the group-IV adsorbates (C, Si, Ge, Sn, and Pb) on the GaAs(0 0 1)-(1 × 2) surface considered in two different models: (i) non-segregated Ga-IV-capped structure and (ii) segregated structure in which the group-IV atoms occupying the second layer while the As atom floats to the surface. The non-segregated structure is energetically more favorable than the segregated structure for Sn and Pb, whereas it is the other way around for C, Si, and Ge.     

A DFT study of the transition metal promotion effect on ethylene chemisorption on Co(0 0 0 1)

Transition metals are often introduced to a catalyst as promoters to improve catalytic performance. In this work, we study the promotion effect of transition metals on Co, the preferred catalytic metal for Fischer–Tropsch synthesis because of its good compromise of activity, selectivity and stability, for ethylene chemisorption using density functional theory (DFT) calculations, aiming to provide some insight into improving the α-olefin selectivity. In order to obtain the general trend of influence on ethylene chemisorption, twelve transition metals (Zr, Mn, Re, Ru, Rh, Ir, Ni, Pd, Pt, Cu, Ag and Au) are calculated. We find that the late transition metals (e.g. Pd and Cu) can decrease ethylene chemisorption energy. These results suggest that the addition of the late transition metals may improve α-olefin selectivity. Electronic structure analyses (both charge density distributions and density of states) are also performed and the understanding of calculated results is presented.     

Atomic and electronic properties of furan on the Si(0 0 1)-(2 × 2) surface

The atomic and electronic properties of the adsorption of furan (C₄H₄O) molecule on the Si(1 0 0)-(2 × 2) surface have been studied using ab initio calculations based on pseudopotential and density functional theory. We have considered two possible chemisorption mechanisms: (i) [4 + 2] and (ii) [2 + 2] cycloaddition reactions. We have found that the [4 + 2] interaction mechanism was energetically more favorable than the [2 + 2] mechanism, by about 0.2 eV/molecule. The average angle between the CC double bond and Si(1 0 0) surface normal was found to be 22°, which is somewhat smaller than the experimental value of 28°, but somewhat bigger than other theoretical value of 19°. The electronic band structure, chemical bonds, and theoretical scanning tunneling microscopy images have also been calculated. We have determined a total of six surface states (one unoccupied and five occupied) in the fundamental band gap. Our results are seen to be in good agreement with the recent near edge X-ray absorption fine structure and high resolution photoemission spectroscopy data.     

Adsorption of methanol and methoxy on NiAl(1 1 0) and Ni3Al(1 1 1): A DFT study

The adsorption of methanol and methoxy on NiAl(1 1 0) and Ni₃Al(1 1 1) has been investigated using density functional theory (DFT). Optimised adsorption geometries and core level shifts are presented. On both surfaces we find that methanol binds to the Al on-top site via its oxygen atom and with the C–O axis tilted away from the surface normal. Methoxy also shows a preference for Al-dominated sites. On NiAl(1 1 0), we predict that methoxy adsorbs with its oxygen atom in the Al–Al bridge site, while it is determined to be adsorbed with its oxygen atom in a 2Ni + Al hollow site on Ni₃Al(1 1 1), closer to Al than Ni. Surface and adsorbate induced binding energy shifts in the Al 2p states are calculated and found to be in good agreement with experimental high resolution photoelectron spectroscopy results.     

Excess molar volumes, viscosities, and refractive indices for binary and ternary mixtures of {cyclohexanone (1) + N,N-dimethylacetamide (2) + N,N-diethylethanolamine (3)} at (298.15, 308.15, and 318.15) K

Densities ρ, viscosities η, and refractive indices n_D, of the binary and ternary mixtures formed by cyclohexanone + N,N-dimethylacetamide + N,N-diethylethanolamine were measured at (298.15, 308.15, and 318.15) K for the liquid region and at ambient pressure for the whole composition ranges. The excess molar volumes V_m^E, viscosity deviations Δη, and refractive index deviations Δn_D, were calculated from experimental densities and refractive indices. The excess molar volumes are positive over the mole fraction range for binary mixtures of cyclohexanone(1) + N,N-dimethylacetamide (2) and N,N-dimethylactamide (2) + N,N-diethylethanolamine (3) and increase with increasing temperatures from (298.15 to 318.15) K. The excess molar volumes of cyclohexanone (1) + N,N-diethylethanolamine (3) are S-shaped dependence on composition with negative values in the N,N-diethylethanolamine rich-region and positive values at the opposite extreme and increase with increasing temperatures from (298.15 to 318.15) K. The excess molar volumes are positive over the whole mole fraction ranges for the ternary mixtures at all temperatures. Viscosity deviations are negative over the mole fraction range for all binary and ternary mixtures and decrease with increasing temperatures from (298.15 to 318.15) K. Refractive index deviations are negative over the mole fraction range for all binary and ternary mixtures and increase with increasing temperatures from (298.15 to 318.15) K. The experimental data of constitute were correlated as a function of the mole fraction by using the Redlich–Kister equation for binary and , Cibulka, Jasinski and Malanowski , Singe et al., Pintos et al., Calvo et al., Kohler, and Jacob–Fitzner for ternary mixture, respectively. McAllister^'s three body, Hind, and Nissan–Grunberg models were used for correlating the kinematic and dynamic viscosity of binary mixtures. The experimental data of the constitute binaries are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures.     

Adsorption of methanol on Ni3Al(1 1 1) and NiAl(1 1 0): A high resolution PES study

The adsorption of methanol on Ni₃Al(1 1 1) and NiAl(1 1 0) has been studied using high resolution photoemission spectroscopy (HR-PES) and density functional theory (DFT). Both methanol and methoxy are formed on these surfaces after the initial methanol exposure at low temperatures. Heating to 200 K leads to further formation of methoxy. On NiAl(1 1 0) two different methoxy species are observed where the first is formed upon methanol adsorption, and the other results from methanol decomposition during heating. The DFT calculations show that methanol and methoxy interacts with the Al atoms on both surfaces. Methanol is found to bond through the oxygen atom to the Al on-top site on Ni₃Al(1 1 1) and NiAl(1 1 0) with the C–O axis tilted with respect to the surface normal. On Ni₃Al(1 1 1) methoxy is situated in a 2Ni+Al hollow site, whereas on NiAl(1 1 0) the Al–Al bridge site is preferred.     

Comparison of sulfur interaction with hydrogen on Pt(1 1 1), Ni(1 1 1) and Pt3Ni(1 1 1) surfaces: The effect of intermetallic bonding

Adsorption strengths of hydrogen and sulfur both individually and together as co-adsorbates were investigated on Pt(1 1 1), Ni(1 1 1) and Pt₃Ni(1 1 1) surfaces using density functional theory in order to determine the effect of metal alloying on sulfur tolerance. The adsorption strengths of H and S singly follow the same trend: Ni(1 1 1) > Pt(1 1 1) > Pt₃Ni(1 1 1), which correlates well with the respective d-band center positions of each surface. We find that the main effect of alloying is to distort both the sub-layer structure and the Pt overlayer resulting in a lowered d-band. For all three surfaces, the d-band shifts downward non-linearly as a function of S coverage. Nearly identical decreases in d-band position were calculated for each surface, leading to an expectation that subsequent adsorption of H would scale with surface type similarly to single species adsorption. In contradiction to this expectation, there was no clearly discernable difference between the energies of coadsorbed H on Pt(1 1 1) and Ni(1 1 1) and only a slightly lowered energy on Pt₃Ni(1 1 1). This provides evidence that coadsorbed species in close proximity interact directly through itinerant mobile electrons and through electrostatic repulsion rather than solely through the electronic structure of the surface. The combination of the lowered d-band position (arising from distorted geometry) and direct co-adsorbate interactions on Pt₃Ni(1 1 1) leads to a lower energy barrier for H₂S formation on the surface compared to pure Pt(1 1 1). Thus, alloying Pt with Ni both decreases the likelihood of S adsorption and favors S removal through H₂S formation.     

Short-time sonolysis of chlorobenzene in the presence of Pd(II) salts and Pd(0)

The effect of PdSO₄, PdCl₂ and Pd(0) on the degradation of chlorobenzene in aqueous solution within 10 min under 200 kHz ultrasonic irradiation, was investigated. The reaction products remaining in the aqueous mixture were analyzed and quantified. The mechanism of chlorobenzene decomposition having benzene as key intermediate is discussed.