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Motivations

Motivations. Mixtures with organic acids have presented difficulties for an EOS approach Recently developed association models are still not adequate for mixtures with organic acids in EOS frames

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Motivations

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  1. Motivations Mixtures with organic acids have presented difficulties for an EOS approach Recently developed association models are still not adequate for mixtures with organic acids in EOS frames The possibility of the extension and the application of Veytsman statistics (1990) was investigated

  2. O H - O = = -C C- - - O - H O Introduction Organic acids generally form dimers in vapor phase - - - - The dimer formations are long been considered only in vapor phase

  3. EOS with Specific Interaction Approaches Chemical theories : APACT used different hydrogen bonding parameters in each phases Physical theories : SAFT denoted a large single associative site for dimer formations Quasichemical theories : NLF-HB EOS cannot describe the dimer formations explicitly

  4. The Composition of Veytsman Statistics Donors and acceptors distribution The probability for an acceptor to be placed the HB location of a donor The Veytsman statistics

  5. Lattice Partition Function • PHYS: You et al. (1994) • HB : Proposed extension of Veytsman statistics for both dimers and n-mers • Pij : Proposed probability of finding an acceptor site j around donor site i for a loosely connected pair ij • For j to be adjacent to i (1) acceptor j must find a specific site ( = 1/Nr) and (2) the site is not occupied by physically interacting groups ( = NrH/Nr)

  6. Thermodynamic Properties • Pressure and chemical potentials • The physical parts are given by You et al. (1994)

  7. Physical Parameters • The coordination number : z=10 • Lattice volume : VH = 9.75 cm3/mol • Pure parameters (ri, ii) : Fitted to saturated liquid density and vapor pressure and correlated (T0 = 298.15 K) • Binary parameter (ij) : Regressed from VLE data • 12 = (1122)1/2(1-12)

  8. Hydrogen Bonding Parameters • The segment number of donors and acceptors : rH = 0.05 • AHii = UHii – TSHii • AHij = (AHiiAHjj)(1/2) • AHij = (0.5AHiiAHjj)(1/2) ( for solvation with acid )

  9. Temperature Coefficients of Physical Parameters

  10. Comparison of the Present Model with Data

  11. Figure. Comparison of present results and SAFT with experimental data for water + acetic acid at different temperatures

  12. Figure. Comparison of present results and SAFT with experimental data for acetic acid + propanoic acid at 313.15 K

  13. Figure. Comparison of present results and SAFT with experimental data for 1-propanol + water at 363.15 K

  14. Figure. Comparison of present results with experimental data for n-heptane + acetic acid at different temperatures

  15. Figure. Comparison of present results with experimental data for butylamine + n-heptane at different temperatures

  16. Conclusions The Veytsman statistics is extended to dimer formations The extended statistics is combined with the Lattice Fluid Theory of You et al.(1994) to give revised NLF-HB EOS The NLF-HB EOS is applied to binary mixtures of alkane, alcohol, acid, amine, and water Good agreements with experimental data were obtained

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