Free acidity of aqueous solutions was initially defined in 1909 by Søren Peter Lauritz Sørensen as pH = −lgcH+ (c/mol·dm−3 or m/mol·kg−1 of the free hydrogen ions in solution, H+) soon (1910) was changed to pH = paH+ = −lgaH+, integrating the new concepts of activity, ai and activity coefficient γi, for the ionic species i under concern, H+ in this case; it is ai = −lg(miγi). Since individual i...

an extended peng-robinson equation of state (epr-eos) is used to model the vapor-liquid equilibrium (vle) in systems containing (water + nacl + co2), (water + methanol + nacl + co2), (water + na2so4 + co2) and (water + nh4cl + co2). the binary and ternary interaction parameters between salt and solvent are adjusted to experimental mean solvent activity of salts (nacl and na2so4). for the system...

MSTor is a computer program for calculating gas-phase molecular partition functions and thermodynamic functions (standard state energy, enthalpy, entropy, free energy, and heat capacity at constant pressure) as functions of temperature by the multistructural approximation with torsional anharmonicity (MS-T). The MS-T approximation accounts for the coupling of torsions to one another and to over...

The analogy between the restricted primitive model and capacitor circuits, originally described decades ago for Mean Spherical Approximation, is explored to demonstrate its transferability in linearized electrolyte theories. On this basis, we offer an explanation of why treating salt diameter as a free adjustable parameter blurs differences theories calculation mean ionic activity coefficients....

the solubility of naproxen in binary mixtures of polyethylene glycol 200 (peg 200) + water at the temperature range from 298.0 k to 318.0 k were reported. the combinations of jouyban-acree model + van’t hoff and jouyban-acree model + partial solubility parameters were used to predict the solubility of naproxen in peg 200 + water mixtures at different temperatures. combination of jouyban-acree m...

The fundamentals of scaling during waterflooding an oilfield are presented. Mineral precipitation is described using both the kinetics approach, with corresponding equations given, and thermodynamic models’ theoretical foundation discussed—mainly specific ion interaction Pitzer models. This paper focuses on process mixing incompatible waters water injection production from oilfield, as this was...

We report our continued progress on the development of a thermochemical model of aluminum silicate mineral solubilities in aqueous solutions containing H, Na, K, Al, Cl, Si(OH)4, SiO(OH)3 , OH, Al(OH), Al(OH)2 , Al(OH)3 , Al(OH)4 − as a function of pH to high salt concentrations (I ≤ 5 m). Prior conference proceedings outlined our progress in developing an accurate model for the potassium free ...

wax precipitate is one of the most serious issues the oil industry is currently facing, since it can cause some troubles such as increasing of the pressure losses in pipe which subsequently increases the required power for pumpage. to remove this problem, prediction of wax disappearance temperature (wdt) seems necessary. in this study, the pressure influence on the wax disappearance temperature...

Understanding of CO2 hydrate–liquid water two-phase equilibrium is very important for storage in deep sea and submarine sediments. This study proposed an accurate thermodynamic model to calculate solubility pure seawater at (HLWE). The van der Waals–Platteeuw coupling with angle-dependent ab initio intermolecular potentials was used the chemical potential hydrate phase. Two methods were describ...