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Volumetric, Ultrasonic and Viscosimetric Studies for the Binary Mixture (1, 4-Dioxane + Water) at T = (295.15, 298.15, 301.15, 304.15, 307.15, 310.15 and 313.15) K

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Abstract

Density, speed of sound and viscosity data for the binary mixtures (1,4-dioxane (1) + water (2)), were measured over the whole composition range at temperatures T = (295.15, 298.15, 301.15, 304.15, 307.15, 310.15 and 313.15) K and at the atmospheric pressure. From experimental data, the excess molar volume, isobaric thermal expansion coefficient, excess of isobaric thermal expansion coefficient, excess speed of sound, isentropic compressibility, excess of isentropic compressibility, intermolecular free-length, the excess intermolecular free-length, the viscosity deviation, the excess free Gibbs energies of activation of viscous flow, the internal pressure, excess internal pressure, acoustic impedance, the excess acoustic, and the free volume were calculated. The excess parameters were fitted by the Redlich–Kister polynomial equation to derive the coefficients and estimate the standard error values. The nature of molecular interactions between the two components of the mixture, have been discussed by means of the thermodynamic properties.

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References

  1. Aminabhavi, T.M., Gopalakrishna, G.: Density, viscosity, refractive index, and speed of sound in aqueous mixtures of N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, acetonitrile, ethylene glycol, diethylene glycol, 1,4-dioxane, tetrahydrofuran, 2-methoxyethanol, and 2-ethoxyethanol at 298.15 K. J. Chem. Eng. Data 40, 856–861 (1995)

    Article  CAS  Google Scholar 

  2. Aminabhavi, T.M., Patil, V.B.: Density, viscosity, refractive index, and speed of sound in binary mixtures of ethenylbenzene with N,N-dimethylacetamide, tetrahydrofuran, N,N-dimethylformamide, 1,4-dioxane, dimethyl sulfoxide, chloroform, bromoform, and 1-chloronaphthalene in the temperature interval (298.15–308.15) K. J. Chem. Eng. Data 43, 497–503 (1998)

    Article  CAS  Google Scholar 

  3. Baragi, J.G., Aralaguppi, M.I., Aminabhavi, T.M., Kariduraganavar, M.Y., Kittur, A.S.: Density, viscosity, refractive index, and speed of sound for binary mixtures of anisole with 2-chloroethanol, 1,4-dioxane, tetrachloroethylene, tetrachloroethane, DMF, DMSO, and diethyl oxalate at (298.15, 303.15 and 308.15) K. J. Chem. Eng. Data 50, 910–916 (2005)

    Article  CAS  Google Scholar 

  4. Nayak, J.N., Aralaguppi, M.I., Aminabhavi, T.M.: Density, viscosity, refractive index, and speed of sound in the binary mixtures of 1,4-dioxane + ethanediol, + hexane, + tributylamine, or + triethylamine at (298.15, 303..15 and 308.15) K. J. Chem. Eng. Data 48, 1152–1156 (2003)

    Article  CAS  Google Scholar 

  5. Pal, A., Kumar, H., Gaba, R.: Density and speed of sound for binary mixtures of 1,4-dioxane with propanol and butanol isomers at different temperatures. J. Mol. Liq. 187, 278–286 (2013)

    Article  CAS  Google Scholar 

  6. Tôrres, R.B., Marchiore, A.C.M., Volpe, P.L.O.: Volumetric properties of binary mixtures of (water + organic solvents) at temperatures between T = 288.15 K and T = 303.15 K at p = 0.1 MPa. J. Chem. Thermodyn. 38, 526–541 (2006)

    Article  CAS  Google Scholar 

  7. Giner, B., Lafuente, C., Villares, A., Haro, M., López, M.C.: Volumetric and refractive properties of binary mixtures containing 1,4-dioxane and chloroalkanes. J. Chem. Thermodyn. 39, 148–157 (2007)

    Article  CAS  Google Scholar 

  8. Omota, L.M., Lulian, O., Omota, F., Ciocîrlan, O.: Densities and derived properties of water, 1,4-dioxane and dimethyl sulfoxide binary and ternary systems at temperatures from 293.15 K to 313.15 K. Rev. Roum. Chim. 54, 63–73 (2009)

    CAS  Google Scholar 

  9. Contreras, M.S.: Densities and viscosities of binary mixtures of 1,4-dioxane with 1-propanol and 2-propanol at (25, 30, 35, and 40) °C. J. Chem. Eng. Data 46, 1149–1152 (2001)

    Article  CAS  Google Scholar 

  10. Banipal, P.K., Singh, V., Kaur, N., Sharma, R., Thakur, S., Kaur, M., Banipal, T.S.: Physico-chemical studies on binary mixtures of 1,4-dioxane and alkan-1-ols at 298.15 K. Proc. Natl. Acad. Sci. India. 88, 479–490 (2018)

    CAS  Google Scholar 

  11. Gupta, M., Vibhu, I., Shukla, J.P.: Refractive index, molar refraction deviation and excess molar volume of binary mixtures of 1,4-dioxane with carboxylic acids. Phys. Chem. Liq. 48, 415–427 (2010)

    Article  CAS  Google Scholar 

  12. Li, X., Cong, Y., Li, W., Yan, P., Zhao, H.: Thermodynamic modeling of solubility and preferential solvation for ribavirin (II) in co-solvent mixtures of (methanol, n-propanol, acetonitrile or 1,4-dioxane) + water. J. Chem. Thermodyn. 115, 74–83 (2017)

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Iulian, O., Ciocirlan, O.L.: Viscosity and density of systems with water, 1,4-dioxane and ethylene glycol between (293.15 and 313.15) K. I. Binary systems. Rev. Roum. Chim. 55, 45–53 (2010)

    CAS  Google Scholar 

  14. Rathnam, M.V., Ambavadekar, D.R., Nandini, M.: Densities, viscosities, and sound speed of binary mixtures of hexyl acetates with tetrahydofuran, 1,4-dioxane, anisole, and butyl vinyl ether. J. Chem. Eng. Data 58, 3370–3377 (2013)

    Article  CAS  Google Scholar 

  15. Rajgopal, K., Chenthilnath, S.: Study on excess thermodynamic parameters and theoretical estimation of ultrasonic velocity of 2-methyl-2-propanol with nitriles at different temperatures. J. Chinese Chem. Eng. 18, 806–816 (2010)

    Google Scholar 

  16. Sastry, S.S., Babu, S., Vishwam, T., Tiong, H.S.: Excess parameters for binary mixtures of alkyl benzoates with 2-propanol at different temperatures. J. Therm. Anal. Calorim. 114, 923–935 (2014)

    Article  CAS  Google Scholar 

  17. Pandey, J.D., Rai, R.D., Shukla, R.K., Shukla, A.K., Mishra, N.: Ultrasonic and thermodynamic properties of quaternary liquid system at 298.15 K. Indian J. Pure Appl. Phys. 31, 84–90 (1993)

    CAS  Google Scholar 

  18. Almassi, M.: Densities and viscosities of the mixtures (formamide + 2-alkanol): Experimental and theoretical approaches. J. Chem. Thermodyn. 69, 101–106 (2014)

    Article  CAS  Google Scholar 

  19. Narendra, K., Srinivasu, Ch., Kalpana, Ch., Narayanamurthy, P.: Excess thermodynamical parameters of binary mixtures of toluene and mesitylene with anisaldehyde using ultrasonic technique at different temperatures. J. Therm. Anal. Calorim. 107, 25–30 (2012)

    Article  CAS  Google Scholar 

  20. Dubey, G.P., Kumar, K.: Densities, viscosities and speeds of sound of binary liquid mixtures of ethylenediamine with alcohols at T = (293.15 to 313.15) K. J. Chem. Eng. Data 56, 2995–3003 (2011)

    Article  CAS  Google Scholar 

  21. Jain, P., Signh, M.: Density, viscosity of binary liquid mixtures of propylene carbonate with polar and nonpolar solvents. J. Chem. Eng. Data 49, 1214–1217 (2004)

    Article  CAS  Google Scholar 

  22. Kouissi, T., Bouanz, M., Ouerfelli, N.: KCl-induced phase separation of 1,4-dioxane + water mixtures studied by electrical conductivity and refractive index. J. Chem. Eng. Data 54, 566–573 (2009)

    Article  CAS  Google Scholar 

  23. Kouissi, T., Bouanz, M.: Transport properties in 1,4-dioxane + water + saturated KCl critical mixture by measuring viscosity and electrical conductivity. J. Chem. Eng. Data 55, 320–326 (2010)

    Article  CAS  Google Scholar 

  24. Ouerfelli, N., Kouissi, T., Olga, I.: The relative reduced Redlich-Kister and Herráez equations for correlating viscosities of 1,4-dioxane + water mixtures at temperatures from 293.15 K to 323.15 K. J. Solution Chem. 39, 57–75 (2010)

    Article  CAS  Google Scholar 

  25. Kouissi, T., Toumi, A., Bouanz, M.: Density, speed of sound, and refractive index measurements for the binary mixture (1, 4-dioxane + isobutyric acid) at T= (295.15, 298.15, 301.15, 304.15, 307.15, 310.15, and 313.15) K. J. Chem. Eng. Data 60, 1975–1985 (2015)

    Article  CAS  Google Scholar 

  26. Giner, B., Villares, A., Gascón, I., Cea, P., Lafuente, C.: Speeds of sound and isentropic compressibilities of binary mixtures containing cyclic ethers and haloalkanes at 298.15 and 313.15K. Int. J. Thermophys. 25, 1735–1746 (2004)

    Article  CAS  Google Scholar 

  27. Kushare, S.K., Kolhaurkar, R.R., Dagade, D.H., Patil, K.J.: compressibility studies of binary solutions involving water as a solute in nonaqueous solvents at T = 298.15 K. J. Chem. Eng. Data 51, 1617–1623 (2006)

    Article  CAS  Google Scholar 

  28. Takigawa, T., Ogawa, H., Nakamura, M., Tamura, K., Murakami, S.: Thermodynamic properties (\(H_{m}^{{\text{E}}} ,\;C_{{p,m}}^{{\text{E}}} ,\;V_{{\text{m}}}^{{\text{E}}} ,\;\kappa _{T}^{{\text{E}}}\)) of binary mixtures (x l,3-Dioxane + (1–x) Cyclohexane) at 298.15 K. Fluid Phase Eqilib. 110, 267–281 (1995)

    Article  CAS  Google Scholar 

  29. Klimaszewski, K., Lewkowska, E.S., Soliwoda, K., Bald, A.: Acoustic and volumetric studies on water + diethylene glycol mixtures in a wide temperature range. Comparison with mixtures of water with tri- and tetraethylene glycol. J. Mol. Liq. 215, 520–533 (2016)

    Article  CAS  Google Scholar 

  30. Vural, U.S., Durmaz, F., Kocyigit, O., Kocyigit, H., Muradogl, V., AkinExcess, B.: Molar volumes, viscosity, refractive index, and Gibbs energy of activation of binary biodiesel + benzene, and biodiesel + toluene mixtures at 298.15 and 303.15 K. Russ. J. Phys. Chem. A 82, 2260–2268 (2008)

    Article  CAS  Google Scholar 

  31. George, J., Sastry, N.V.: Densities, dynamic viscosities, speeds of sound, and relative permittivities for water + alkanediols (propane-1,2- and -1,3-diol and butane-1,2-, -1,3-, 1,4-, and -2,3-diol) at different temperatures. J. Chem. Eng. Data 48, 1529–1539 (2003)

    Article  CAS  Google Scholar 

  32. Catrinciuc, M., Iulian, O., Omota, L.M., Nițǎ, I.: Experimental and calculated properties in binary and ternary systems with water, 1,4-dioxane and diethylene glycol at 298.15 K. Rev. Roum. Chim. 51, 1011–1018 (2006)

    CAS  Google Scholar 

  33. Martinez, M.A.R., Martínez, F.: Volumetric properties of the pharmaceutical model cosolvent system 1,4-dioxane + water at several temperatures. Vitae 16, 327–337 (2009)

    Article  Google Scholar 

  34. Besbes, R., Ouerfelli, N., Latrous, H.: Density, dynamic viscosity, and derived properties of binary mixtures of 1,4-dioxane with water at T = 29815 K. J. Mol. Liq. 145, 1–4 (2009)

    Article  CAS  Google Scholar 

  35. Findaly, A., Levitt, B.P.: Findlay’s Practical Physical Chemistry, 9th edn. Longman, New York (1973)

    Google Scholar 

  36. Weast, R.C., Astle, M.J.: CRC Handbook of Chemistry and Physics, 60th edn. CRC Press, Boca Raton, FL (1980)

    Google Scholar 

  37. Redlich, O., Kister, A.T.: Algebraic representation of thermodynamic properties and the classification of solutions. Ind. Eng. Chem. 40, 345–348 (1948)

    Article  Google Scholar 

  38. Muhammad, A.S., Shamim, A., Shamsuddin, M.A., Mohammad, H.U.: Excess molar volumes and thermal expansivities of aqueous solutions of dimethylsulfoxide, tetrahydrofuran and 1,4-dioxane. Phys. Chem. Liq. 40, 621–635 (2002)

    Article  CAS  Google Scholar 

  39. Estrada-Baltazar, A., Iglesias-Silva, G.A., Caballero-Cerón, C.: Volumetric and transport properties of binary mixtures of n-octane + ethanol, + 1-propanol, + 1-butanol, and + 1-pentanol from (29315 to 32315) K at atmospheric pressure. J. Chem. Eng. Data 58, 3351–3363 (2013)

    Article  CAS  Google Scholar 

  40. George, C.B., Osamu, K.: Evaluation of excess isentropic compressibilities and isochoric heat capacities. J. Chem. Thermodyn. 11, 1061–1064 (1979)

    Article  Google Scholar 

  41. Iloukhani, H., Samiey, B.: Excess molar volumes, viscosities and speeds of sound of the ternary mixture 1-heptanol (1) + tetrachloroethylene (2) + methylcyclohexane (3) at 298.15 K. J. Solution Chem. 36, 691–714 (2007)

    Article  CAS  Google Scholar 

  42. Rezaei-Sameti, M., Rakhshi, M.: Excess thermodynamic parameters for binary and ternary mixtures of 1-butanol (1) + cyclohexylamine (2) + n-heptane (3) at different temperatures: a theoretical study. Arab. J. Chem. 10, S691–S699 (2017)

    Article  CAS  Google Scholar 

  43. Tamura, K., Nakamura, M.S., Murakami, S.: Excess volumes of water + acetonitrile and water + dimethylsulfoxide at 30 °C and the effect of the excess thermal expansivity coefficients on derived thermodynamic properties. J. Solution Chem. 26, 1199–1207 (1997)

    Article  CAS  Google Scholar 

  44. Rezaei-Sameti, M., Rakhshi, M.: Derived thermodynamic properties of [o-xylene or p-xylene + (acetic acid or tetrahydro-furan)] at different temperatures and pressures. Bull. Chem. Soc. Ethiop. 25, 273–286 (2011)

    Article  Google Scholar 

  45. Douhéret, G., Davis, M.I., Reis, J.C.R., Blandamer, M.J.: Isentropic compressibilities-experimental origin and the quest for their rigorous estimation in thermodynamically ideal liquid mixtures. Chem. Phys. Chem. 2, 148–161 (2001)

    Article  PubMed  Google Scholar 

  46. Douhéret, G., Morau, C., Viallard, A.: Excess thermodynamic quantities in binary systems of non electrolytes: different ways of calculating excess compressibilities. Fluid Phase Equilib. 22, 277–287 (1985)

    Article  Google Scholar 

  47. Douhéret, G., Davis, M.L., Reis, J.C.R.: Excess isentropic compressibility and excess ultrasound speed in binary and ternary liquid mixtures. Fluid Phase Equilib. 231, 246–249 (2005)

    Article  CAS  Google Scholar 

  48. Kumar, H., Sharma, S.: Acoustical studies of binary liquid mixtures of cylopentane with 1-alkanol at different temperatures and different approaches for ideal mixing lows. J. Solution Chem. 39, 967–986 (2010)

    Article  CAS  Google Scholar 

  49. Ricardo, F.C., Volpe, P.L.O.: Measurements of the molar heat capacities and excess molar heat capacities for water + organic solvents mixtures at 288.15 K to 303.15 K and atmospheric pressure. J. Solution. Chem. 39, 259–276 (2010)

    Article  CAS  Google Scholar 

  50. Khan, V.H., Subrahmanyam, S.V.: Excess thermodynamic functions of the systems: benzene + p-xylene and benzene + p-dioxan. Trans. Faraday Soc. 67, 2282–2291 (1971)

    Article  CAS  Google Scholar 

  51. García-Miaja, G., Troncoso, J., Romaní, L.: Excess enthalpy, density and heat capacity for binary systems of alkylimidazolium-based ionic liquids + water. J. Chem. Thermodyn. 41, 161–166 (2009)

    Article  CAS  Google Scholar 

  52. Indra, B., Nirmala, D., Paramespri, N., Deresh, R.: 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 3313.15) K. J. Chem. Thermodyn. 57, 203–211 (2013)

    Article  CAS  Google Scholar 

  53. Victor, P.J., Das, D., Hazra, D.K.: Excess molar volumes, viscosity deviations and isentropic compressibility changes in binary mixtures of N,N-dimethylacetamide with 2-methoxy ethanol and water in the temperature range 298.15 to 318.15 K. J. Indian Chem. Soc. 81, 1045–1050 (2004)

    CAS  Google Scholar 

  54. Jacobson, B.: Intermolecular free lengths in the liquid state. Acta Chem. Scand. 6, 1485–1498 (1952)

    Article  CAS  Google Scholar 

  55. Kincaud, J.F., Eyring, H.: Free volumes and free angle ratios of molecules in liquids. J. Chem. Phys. 6, 620–629 (1938)

    Article  Google Scholar 

  56. Ali, A., Nain, A.K.: Ultrasonic study of molecular interactions in N,N-dimethylacetamide + ethanol binary mixtures at various temperatures. Acoust. Lett. 19, 181–187 (1996)

    CAS  Google Scholar 

  57. Awasthi, A., Rastogi, M., Gupta, M., Shukla, J.P.: Ultrasonic investigation of molecular association in ternary mixtures. J. Mol. Liq. 80, 77–88 (1999)

    Article  CAS  Google Scholar 

  58. Santosh, M.S., Lyubartsev, A., Mirzoev, A., Bhat, D.K.: Solute–solvent interactions in aqueous glycylglycine–CuCl2 solutions: acoustical and molecular dynamics perspective. J. Solution Chem. 40, 1657–1671 (2011)

    Article  CAS  Google Scholar 

  59. Naseem, B., Iftikha, M.: Investigation on molecular interactions of antibiotics in alcohols using volumetric and acoustic studies at different temperatures. J. Chem. Thermodyn. 104, 239–251 (2017)

    Article  CAS  Google Scholar 

  60. Vanathi, V., Mullainathan, S., Nithiyanatham, S., Ramasamy, V., Palaniappan, L.: Ultrasonic velocity, density, viscosity for the ternary mixture of (benzene + chloroform/cyclohexane) at different temperatures. Heliyon 5, e02203 (2019)

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  61. Noria, T.S., Babavalib, S.F., Srinivasuc, C.: Study of temperature dependant excess acoustical factors of mixtures of binary liquids of aniline with mesitylene at T = (303.15, 308.15, 313.15 and 318.15) K. Mater. Today Proc. 5, 25758–25765 (2018)

    Article  CAS  Google Scholar 

  62. Ouerfelli, N., Barhoumi, Z., Iulian, O.: Viscosity Arrhenius activation energy and derived partial molar properties in 1,4-dioxane +water binary mixtures from 293.15 to 323.15 K. J. Solution Chem. 41, 458–474 (2012)

    Article  CAS  Google Scholar 

  63. Meyer, R., Meyer, M., Metzeger, J., Peneloux, A.: Etude thermodynamique des mélanges binaries-I.—Etude comparative entre les enthalpies libres d’excés d’activation du flot visqueux et les enthalpies libres d’exés de solution. J. Chim. Phys. 68, 406–412 (1971)

    Article  CAS  Google Scholar 

  64. Kartsev, V.N., Pankin, K.E., Batov, D.V.: On interrelation between the internal pressure and the cohesion energy density. J. Struct. Chem. 47, 277–284 (2006)

    Article  CAS  Google Scholar 

  65. Kartsev, V.N., Shtykov, S.N., Pankin, K.E.: To evaluation of the state of the own macroscopic force field of liquids. J. Struct. Chem. 58, 712–717 (2017)

    Article  CAS  Google Scholar 

  66. Egorov, G.I., Makarov, D.M.: Effect of high pressure and temperature on the volume properties of the liquid-phase mixture of {water (1) + formamide (2)}. J. Mol. Liq. 254, 154–165 (2018)

    Article  CAS  Google Scholar 

  67. Suryanarayana, C.V., Kuppusami, J.: Free volume and internal pressure of liquid from ultrasonic velocity. J. Acosut. Soc. Ind. 4, 75–82 (1979)

    Google Scholar 

  68. Suryanarayana, C.V.: Internal pressure in liquid-systems and its measurements. Ind. J. Pure Appl. Phys. 27, 751–757 (1989)

    CAS  Google Scholar 

  69. Pandey, J.D., Shukla, A.K., Tripathi, N., Dubey, G.P.: Internal pressure, ultrasonic velocity and viscosity of multi-component liquid systems. Pramana 40, 81–87 (1993)

    Article  CAS  Google Scholar 

  70. Kumar, R., Mahesh, R., Shanmugapriyan, B., Kannappan, V.: Volumetric, viscometric, acoustic and refractometric studies of molecular interactions in certain binary systems of o-chlorophenol at 303.15 K. Ind. J. Pure Appl. Phys. 50, 633–640 (2012)

    CAS  Google Scholar 

  71. Mahendran, G., Palaniappan, I.: Molecular interaction of aniline in toluene + isobutanol system. Ind. J. Pure Appl. Phys. 49, 803–808 (2011)

    CAS  Google Scholar 

  72. Nain, A.K.: Densities and volumetric properties of binary mixtures of tetrahydrofuran with some aromatic hydrocarbons at temperatures from 278.15 to 318.15 K. J. Solution Chem. 35, 1417–1439 (2006)

    Article  CAS  Google Scholar 

  73. Suryanarayana, C.V., Kuppusami, J.: Role of internal pression in the chemistry of electrolyte solution. J. Acoust. Soc. India 9, 4–8 (1981)

    CAS  Google Scholar 

  74. Agnihotri, P.K., Adgaonkar, C.S.: Theoretical evaluation of ultrasonic velocity in binary liquid mixtures. Ultrasonics 27, 248–251 (1989)

    Article  CAS  Google Scholar 

  75. Palani, R., Balakrishana, S.: Acoustical properties of ternary mixtures of 1-alkanols in di-isopropyl ether and 2,2,2-trifluoroethanol mixed solvents. Ind. J. Pure Appl. Phys. 48, 644–650 (2010)

    CAS  Google Scholar 

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Mejri, I., Kouissi, T., Toumi, A. et al. Volumetric, Ultrasonic and Viscosimetric Studies for the Binary Mixture (1, 4-Dioxane + Water) at T = (295.15, 298.15, 301.15, 304.15, 307.15, 310.15 and 313.15) K. J Solution Chem 50, 1131–1168 (2021). https://doi.org/10.1007/s10953-021-01109-z

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