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Research Publications (Applied Sciences)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/213

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Subject: search.filters.subject.Refractive index

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Now showing 1 - 5 of 5
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    Influence of epoxy group in 2-pyrrolidonium ionic liquid interactions and thermo-physical properties with Ethanoic or Propanoic acid at various temperatures
    (ACS Publications, 2016) Vasanthakumar, Arumugam; Redhi, Gan G.; Gengan, Robert Moonsamy
    In this present study, the interaction between a carboxylic acid and ionic liquids, in terms of their binary mixtures and corresponding thermo-physical properties, was investigated. Here, the novel ionic liquid (IL) [EPMpyr]+[Cl]− was synthesized, and it has been mixed with ethanoic or propanoic acids. The influence of the epoxy group in this ionic liquid was more strongly affected with the acids, and their physicochemical properties at varied temperatures are discussed in term of density (ρ), viscosity (η), speed of sound (u), and refractive index (n) measurements. The density (ρ), speed of sound (u), viscosity (η), and refractive index (n) of the IL, ethanoic acid, propanoic acid, and their corresponding binary mixtures {[([EPMpyr]+[Cl]− (1) + ethanoic or propanoic acid (2)} have been measured at T = (293.15–313.15) K and at P = 0.1 MPa. The theoretical thermodynamic properties of excess molar volumes (VmE), isentropic compressibility (ks), deviation in isentropic compressibility (Δks), and intermolecular free length (Lf) are calculated using experimental density and speed of sound data. The VmE and Δks values for both binary mixtures were found to be negative over the entire mole fraction range of composition at all the investigated temperatures. These results suggest the existence of specific interactions between components in the molecules. The experimental data could be helpful to understand the molecular interactions between the IL and carboxylic acid combinations. The experimental data were fitted to the Redlich–Kister polynomial equation.
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    Volumetric, acoustic and refractive index for the binary system (Butyric acid + Hexanoic acid) at different temperatures
    (Springer, 2014-04-12) Bahadur, Indra; Deenadayalu, Nirmala; Naidoo, Paramespri; Ramjugernath, Deresh
    In this paper density, sound velocity, and refractive index for the binary system (butyric acid ? hexanoic acid) were measured over the entire composition range and at 5 K intervals in the temperature range 293.15–313.15 K. The excess molar volumes, isentropic compressibilities, excess isentropic compressibilities, deviation in refractive indices, molar refractions, and deviation in molar refractions were calculated by using the experimental densities, sound velocities, and refractive indices, respectively. The Redlich–Kister equation was used to fit the excess molar volume, excess isentropic compressibility, deviation in refractive index and deviation in molar refraction data. The Lorentz–Lorenz approximation was used to correlate the excess molar volume from the deviation in refractive index and also to predict the density from refractive index or the refractive index from density of the binary mixtures. Four sound velocity mixing rules were tested and the best model for the systems studied in this work was the Berryman mixing rule. The thermodynamic properties are discussed in terms of intermolecular interactions between the components of the mixtures.
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    Effect of temperature on density, sound velocity, refractive index and their derived properties for the binary systems (heptanoic acid + propanoic or butanoic acids)
    (Elsevier, 2014-06-14) Bahadur, Indra; Naidoo, Paramespri; Singh, Sangeeta; Ramjugernath, Deresh; Deenadayalu, Nirmala
    In this work, the effect of temperature on density (q), sound velocity (u), refractive index (n) and their derived properties for carboxylic acid mixtures was studied. The thermophysical properties: density, sound velocity and refractive index were measured over the entire composition range at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K and at p = 0.1 MPa for the binary systems (heptanoic acid + propa-noic or butanoic acids). The mass fraction of water was found to be unusually large and could not be reduced further. The Lorentz–Lorenz approximation was used to predict the density from refractive index or the refractive index from density of the binary mixtures. Sound velocity mixing rules were applied to the experimental sound velocity data. Excess molar volumes, VEm; isentropic compressibilities, js, excess isentropic compressibilities, jsE, and deviation in refractive indices, Dn, were also calculated from the experimental data. The Redlich–Kister polynomial equation was fitted to the excess properties and the deviation in refractive index data. Thermophysical properties are useful in understanding the intermolecular interactions between the components of mixtures.
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    Influence of alkyl group and temperature on thermophysical properties of carboxylic acid and their binary mixtures
    (Elsevier B.V., 2014-06-30) Bahadur, Indra; Deenadayalu, Nirmala; Naidoo, Paramespri; Ramjugernath, Deresh; Singh, Sangeeta
    n this work, volumetric, acoustic and refractive index methods have been used to study the interactions between carboxylic acids mixtures as a function of temperature and concentration. The density (r), sound velocity (u), refractive index (n) of butanoic acid, pentanoic acid and heptanoic acid and their binary systems (butanoic or heptanoic acid + pentanoic acid) have been measured at 293.15, 298.15, 303.15, 308.15 and 313.15 K and at p = 0.1 MPa. The Lorentz–Lorenz approximation and sound velocity mixing rules were used to test the accuracy of the experimental data. The derived properties such as excess molar volumes, VEm, isentropic compressibilities, ks, excess isentropic compressibilities, ksE, and deviation in refractive indices, Dn, were also calculated. The Redlich–Kister polynomial equation was used to fit the excess/deviation properties. These results are useful for describing the intermolecular interactions that exist between the components in mixtures. This work also tests various sound velocity mixing rules to calculate the sound velocity of the binary mixture from pure component data, as well as examine the use of the Lorentz–Lorenz approximation to predict density from refractive index and vice versa.
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    Densities, speeds of sound, and refractive indices for binary mixtures of 1-butyl-3-methylimidazolium methyl sulphate ionic liquid with alcohols at T = (298.15, 303.15, 308.15, and 313.15) K
    (Elsevier, 2012-09-24) Singh, Sangeeta; Aznar, Martin; Deenadayalu, Nirmala
    Experimental densities, speeds of sound, and refractive indices of the binary mixtures {1-butyl-3-methylimidazolium methylsulphate ([BMIM]+[MeSO4]−) + methanol, or 1-propanol, or 2-propanol, or 1-butanol} were measured over the whole range of composition at T = (298.15, 303.15, 308.15, and 313.15) K. From the experimental data, excess molar volumes, excess isentropic compressibilities, deviation in refractive indices and molar refractions were calculated. The excess molar volumes, change in isentropic compressibilities, and deviation in refractive indices were fitted by the Redlich–Kister smoothing polynomial. The Lorentz–Lorenz equation was applied to correlate the volumetric properties and predict the density or the refractive index of the binary mixtures. Results for these quantities have been discussed in terms of intermolecular interactions between the components of the mixtures. For all the systems studied, the excess molar volume and excess isentropic compressibility are negative, while the change in refractive index on mixing is always positive over the entire composition range and at all temperatures.