Van der Waals-like Equations of State. I. Application to Pure Liquids

Phase transitions are introduced using the van der Waals gas as an example. The equations of state are derived from the Helmholtz free energy of the ideal gas. The behavior of this model is analyzed, and an instability leads to a liquid-gas phase transition. The Maxwell construction for the pressure at which a phase transition occurs is derived. The effect of phase transition on the Gibbs free energy and Helmholtz free energy is shown. Latent heat is defined, and the Clausius–Clapeyron equation is derived. Gibbs' phase rule is derived and illustrated.

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van der Waals–Tonks-type equations of state for hard-disk and hard-sphere fluids

Physical Review E ◽

10.1103/physreve.66.031203 ◽

2002 ◽

Vol 66 (3) ◽

Cited By ~ 19

Author(s):

Xian Zhi Wang

Keyword(s):

Hard Sphere ◽

Equations Of State ◽

Van Der Waals ◽

Hard Disk

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A new approach for calculating the accessible volume in equations of state for mixtures. I. Theory and implementation in the van der Waals equation of state

Fluid Phase Equilibria ◽

10.1016/0378-3812(88)87004-3 ◽

1988 ◽

Vol 43 (2-3) ◽

pp. 171-180 ◽

Cited By ~ 3

Author(s):

B. Smit ◽

K.R. Cox

Keyword(s):

Equation Of State ◽

Equations Of State ◽

Van Der Waals ◽

New Approach ◽

Van Der Waals Equation ◽

Accessible Volume

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TOWARDS A MOLECULAR THEORY FOR THE VAN DER WAALS–MAXWELL DESCRIPTION OF FLUID PHASE TRANSITIONS

Journal of Theoretical and Computational Chemistry ◽

10.1142/s0219633602000282 ◽

2002 ◽

Vol 01 (02) ◽

pp. 381-406 ◽

Cited By ~ 33

Author(s):

ANDRIY KOVALENKO ◽

FUMIO HIRATA

Keyword(s):

Hydrogen Bonding ◽

Phase Transitions ◽

Phase Diagrams ◽

Equations Of State ◽

Van Der Waals ◽

Fluid Phase ◽

Carbon Aerogel ◽

Molecular Fluids ◽

Wide Range ◽

Realistic Interaction

We briefly review developments of theories for phase transitions of molecular fluids and mixtures, from semi-phenomenological approaches providing equations of state with adjustable parameters to first-principles microscopic methods qualitatively correct for a variety of molecular models with realistic interaction potentials. We further present the generalization of the van der Waals–Maxwell description of fluid phase diagrams to account for chemical specificities of polar molecular fluids, such as hydrogen bonding. Our theory uses the reference interaction site model (RISM) integral equation approach complemented with the new closure we have proposed (KH approximation), successful over a wide range of density from gas to liquid. The RISM/KH theory is applied to the known three-site models of water, methanol, and hydrogen fluoride. It qualitatively reproduces their vapor-liquid phase diagrams and the structure in the gas as well as liquid phases, including hydrogen bonding. Furthermore, phase transitions of water and methanol sorbed in nanoporous carbon aerogel are described by means of the replica generalization of the RISM approach we have developed. The changes as compared to the bulk fluids are in agreement with simulations and experiment. The RISM/KH theory is promising for description of phase transitions in various associating fluids, in particular, electrolyte as well as non-electrolyte solutions and ionic liquids.

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Application of PC-SAFT and cubic equations of state for the correlation of solubility of some pharmaceutical and statin drugs in SC-CO2

Chemical Industry and Chemical Engineering Quarterly ◽

10.2298/ciceq120407005e ◽

2013 ◽

Vol 19 (3) ◽

pp. 449-460 ◽

Cited By ~ 3

Author(s):

El Abdallah ◽

C. Si-Moussa ◽

S. Hanini ◽

M. Laidi

Keyword(s):

Experimental Data ◽

Equations Of State ◽

Van Der Waals ◽

Energy Parameter ◽

Pure Component ◽

Binary Interaction ◽

Statistical Associating Fluid Theory ◽

Binary Interaction Parameters ◽

Fluid Theory ◽

Statin Drugs

In this work, the solubilities of some anti-inflammatory (nabumetone, phenylbutazone and salicylamide) and statin drugs (fluvastatin, atorvastatin, lovastatin, simvastatin and rosuvastatin) were correlated using the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) with one-parameter mixing rule and commonly used cubic equations of state Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) combining with van-der Waals-1 parameter (VDW1) and van-der Waals-2 parameters (VDW2) mixing rules. The experimental data for studied compounds were taken from literature at temperature and pressure in ranges (308-348 K) and (100-360 bar) respectively. The critical properties required for the correlation with PR and SRK were estimated using Gani and Noonalol contribution group methods whereas, PC-SAFT pure-component parameters; segment number (m), segment diameter (?) and energy parameter (?/k) have been estimated by tihic?s group contribution method for nabumetone. For phenylbutazone and salicylamide those parameters were determined using a linear correlation. For statin drugs, PC-SAFT parameters were fitted to solubility data, and binary interaction parameters (kij and lij) have been obtained by fitting the experimental data. The result was found to be in good agreement with the experimental data and showed that PC-SAFT approach can be used to model solid-SCF equilibrium with better correlation accuracy than cubic equations of state.

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