Representation of VLE and liquid phase composition with an electrolyte model: application to H3PO4–H2O and H2SO4–H2O

Cherif, Mourad; Mgaidi, Arbi; Ammar, M.; Abderrabba, Manef; Fürst, Walter

doi:10.1016/s0378-3812(01)00688-4

Cited by 22 publications

(9 citation statements)

References 14 publications

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“…It is, in principle, possible to adapt these procedures to solve isothermal flash-like problems involving electrolyte systems and there are several examples of vapor-liquid equilibrium computations for electrolyte systems that use Gibbs free energy minimization (Cherif et al, 2000(Cherif et al, , 2002. An example with solid phases is a Gibbs free energy minimization method that uses simple thermodynamic phase models (ideal K-values) to predict gas hydrate precipitation (Ballard and Sloan, 2004) in systems that contain salts.…”

Section: Introductionmentioning

confidence: 99%

A reliable procedure to predict salt precipitation in pure phases

Beltrão

Cardoso

Castier³

2010

Braz. J. Chem. Eng.

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-This article proposes a new procedure to compute solid-liquid equilibrium in electrolyte systems that may form pure solid phases at a given temperature, pressure, and global composition. The procedure combines three sub-procedures: phase stability test, minimization of the Gibbs free energy with a stoichiometric formulation of the salt-forming reactions to compute phase splitting, and a phase elimination test. After the phase splitting calculation for a system configuration that has a certain number of phases, the phase stability test establishes whether including an additional phase will reduce the Gibbs free energy further. The criteria used for phase stability may lead, in some cases, to the premature inclusion of phases that should be absent from the final solution but, if this happens, the phase elimination sub-procedure removes them. It is possible to use the procedure with several excess Gibbs free energy models for liquid phase behavior. The procedure has proven to be reliable and fast and the results are in good agreement with literature data.

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Section: Introductionmentioning

confidence: 99%

A reliable procedure to predict salt precipitation in pure phases

Beltrão

Cardoso

Castier³

2010

Braz. J. Chem. Eng.

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“…Reasons include the partial dissociation of the bisulfate ion, the hydronium and bisulfate complex formation, the different extents of proton hydration (with respect to the initial H 2 SO 4 molality) and the partial dissociation of sulfuric acid at high concentrations (because of the elimination of free water). Attempts to model the sulfuric acid system have led to accurate thermodynamic representations of the system, [13][14][15][16][17] but these are deficient in the prediction of speciation. Considering the complexity of the aqueous sulfuric acid system and the large number of proton hydrates that can exist in this solution, 18 it is indeed an intriguing problem to predict the speciation.…”

Section: Introductionmentioning

confidence: 99%

“…However, the hydration of the ion complexes affects the mass balance equations (i.e., the elemental balances are different when H 2 SO 4 or H 2 SO 4 ÁH 2 O are considered), which is not recognized by the assumption of Sanders. Later, Cherif et al 13 extended the H 2 SO 4 model of Pitzer et al 15,66 by including detailed speciation data in the experimental database used to fit the Pitzer model parameters. They fitted their model to the Raman spectroscopic measurements of Young et al 52 and Chen and Irish 42 and to the osmotic coefficient data of Robinson and Stokes, 8 Zeleznik 40 and Rard et al 37 They simulated the aqueous sulfuric acid solution up to 27 molal, but did not consider hydrates, H 2 SO 4 dissociation equilibria and ions-water complex formation.…”

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confidence: 99%

Refined electrolyte‐NRTL model: Activity coefficient expressions for application to multi‐electrolyte systems

2008

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in Wiley InterScience (www.interscience.wiley.com).The influence of simplifying assumptions of the electrolyte-nonrandom two-liquid (NRTL) model in the derivation of activity coefficient expressions as applied to multi-electrolyte systems is critically examined. A rigorous and thermodynamically consistent formulation for the activity coefficients is developed, in which the simplifying assumption of holding ionic-charge fraction quantities constant in the derivation of activity coefficient expressions is removed. The refined activity coefficient formulation possesses stronger theoretical properties and practical superiority that is demonstrated through a case study representing the thermodynamic properties and speciation of dilute to concentrated aqueous sulfuric acid solutions at ambient conditions. In this case study phenomena, such as hydration, ion pairing, and partial dissociation are all taken into account. The overall result of this study is a consistent, analytically derived, short-range interaction contribution formulation for the electrolyte-NRTL activity coefficients and a very accurate representation of aqueous sulfuric acid solutions at ambient conditions at concentrations up to 50 molal. 2008 American Institute of Chemical Engineers AIChE J, 54: [1608][1609][1610][1611][1612][1613][1614][1615][1616][1617][1618][1619][1620][1621][1622][1623][1624] 2008 Keywords: electrolyte thermodynamics, electrolyte-NRTL, ionic activity coefficients, multi-electrolyte solutions, mixing of electrolytes, aqueous sulfuric acid IntroductionThe electrolyte-nonrandom two-liquid (NRTL) model 1 has been extensively applied to represent thermodynamic properties of various electrolyte systems. Examples include mean ionic activity coefficients of aqueous strong electrolytes 1,2 and aqueous organic electrolytes, 3 phase behavior of weak electrolytes, 1 strong acids, 4 mixed-solvent electrolytes, 5 and so forth. The main reasons for its wide acceptance and application are the incorporation of semi-fundamental chemical theories such as the NRTL model for the simulation of local Correspondence concerning this article should be addressed to G. M. Bollas at bollas@mit.edu. *Disclaimer: This paper was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any age...

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“…Calcium phosphate is commonly used as a source of H 3 PO 4 by heating it with sulfuric acid, and removal the insoluble CaSO 4 , by filtration (Morita, Kubota, and Shin 1990). Phosphoric acid is widely used in the production of agricultural fertilizers, control of bacteria growth in selected processed foods, and the process of clarification of sugar juices (Cherif et al 2002). The carbonated drinks become more acidic after addition of the phosphoric acid.…”

Section: Introductionmentioning

confidence: 99%

Developed Method for Spectroscopic Studies of Viscous Samples

et al. 2008

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In this work, the trace elements in phosphoric acid, which has been considered an example of the proposed viscous sample, were measured accurately by a developed method. Samples were diluted to decrease matrix and background interferences. Quantitative analysis of As, Ca, Cd, Cu, Fe, Hg, K, Mg, Na, Pb, and Zn were carried out using flame atomic absorption spectrometry (FAAS). A comparison with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) proves the validity of the developed method. The change of the electronic transition due to diluted of the viscous samples was demonstrated using UV-VIS spectroscopy.

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Representation of VLE and liquid phase composition with an electrolyte model: application to H3PO4–H2O and H2SO4–H2O

Cited by 22 publications

References 14 publications

A reliable procedure to predict salt precipitation in pure phases

A reliable procedure to predict salt precipitation in pure phases

Refined electrolyte‐NRTL model: Activity coefficient expressions for application to multi‐electrolyte systems

Developed Method for Spectroscopic Studies of Viscous Samples

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