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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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Author: search.filters.author.Deenadayalu, NirmalaSubject: search.filters.subject.Carboxylic acids

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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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    Density, speed of sound, and refractive index measurements for the binary systems (butanoic acid + propanoic acid, or 2-methyl-propanoic acid) at T = (293.15 to 313.15) K
    (Elsevier, 2012-09-17) Bahadur, Indra; Deenadayalu, Nirmala; Naidoo, Paramespri; Ramjugernath, Deresh
    Density, speed of sound, and refractive index for the binary systems (butanoic acid + propanoic acid, or 2-methyl-propanoic acid) were measured over the whole composition range and at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K. The excess molar volumes, isentropic compressibilities, excess isentropic compressibilities, molar refractions, and deviation in refractive indices were also calculated by using the experimental densities, speed of sound, and refractive indices data, respectively. The Redlich–Kister smoothing polynomial equation was used to fit the excess molar volume, excess isentro- pic compressibility and deviation in refractive index data. The thermodynamic properties have been discussed in terms of intermolecular interactions between the components of the mixtures.
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    Solid–liquid equilibria measurements for binary systems comprising (butyric acid + propionic or pentanoic acid) and (heptanoic acid + propionic or butyric or pentanoic or hexanoic acid)
    (Elsevier, 2013-02) Ramjugernath, Deresh; Deenadayalu, Nirmala; Naidoo, Paramespri; Ngema, Peterson Thokozani; Reddy, Prashant; Bahadur, Indra; Tadie, Margreth
    Solid–liquid equilibria (SLE) measurements have been undertaken for carboxylic acid systems comprising (butyric acid + propionic or pentanoic acid) and (heptanoic acid + propionic or butyric or pentanoic or hexanoic acid) via a synthetic method using two complementary pieces of equipment. The measurements have been obtained at atmospheric pressure and over the temperature range of (225.6 to 270.7) K. All the acid mixtures exhibit a eutectic point in their respective phase diagrams, which have been determined experimentally. The estimated maximum uncertainties in the reported temperatures and compositions are ±1 K and ±0.0006 mole fraction, respectively. The experimental data have been satisfactorily correlated with the Wilson and NRTL activity coefficient models.