Equilibria in Electrolyte Solutions

Wright, Margaret Robson

doi:10.1007/978-1-349-09618-3_2

Cited by 10 publications

(22 citation statements)

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“…The Pitzer model was discussed in details elsewhere. 18,20,30 The Bromley model is empirical and results in accurate predictions for strong salt solutions. In salt solutions, eq 4 holds between the osmotic coefficient and activity of water 21,24 :…”

Section: Activity Of Water In the Presence Of Alcoholsmentioning

confidence: 99%

“…For salts, water activity was calculated from Pitzer 20 and Bromley 21 expressions. These two models predict the nonideality of water more accurately than the Debye−Huckel equation 16,18 in the concentrated solutions. Further, this work introduces a combining rule for calculating water activity in the presence of aqueous alcohol + salt solutions.…”

Section: Introductionmentioning

confidence: 98%

“…The main drawbacks of the local composition models are their complexity and correlative basis. 15−17 For calculating water activity in water + salt solutions, several ionic models like the Debye−Huckel model and its modifications, 18 the Pitzer model, 18−20 Bromley model, 18,21−24 Davies model, 18 electrolyte-NRTL model, 25,26 and extended UNIQUAC model 27,28 were utilized. The Debye− Huckel model yields precise outcomes for exceedingly dilute solutions, and by increasing the salt concentration in the solutions, the deviations become noticeable.…”

Section: Introductionmentioning

confidence: 99%

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A Precise Thermodynamic Approach for Calculating Activity of Water in the Presence of Aqueous Alcohol + Salt Solutions and its Application to Gas Hydrate Dissociation Modeling

Keshavarzi,

Rasoolzadeh,

Nasrifar

2024

Ind. Eng. Chem. Res.

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Thermodynamic hydrate inhibitors (THIs) are chemical compounds that are utilized to reduce the activity of water and consequently restrict the hydrate formation zone, which is managed as a result of strong molecular/ionic interactions with water without further participating in the hydrate structure. In this regard, developing a precise and easy-to-use thermodynamic relation to calculate the activity of water in the presence of aqueous THI such as alcohols and salts is of great importance. Such a relation can then be employed within a thermodynamic approach to model hydrate equilibria. The goal of this work was to derive a relationship from the Gibbs−Duhem theory to calculate hydrate dissociation temperatures in the presence of aqueous alcohol + salt solutions. As such, the interactions between salts and mixed solvents (water + alcohol) were described phenomenologically using the Bromley model. The results find applications in the gas and oil industry. To describe the hydrate phase, the van der Waals−Platteeuw (vdW-P) model was utilized. The Peng−Robinson equation of state (EoS) was used to describe the gas phase. To calculate the activity of water in the salt-free water + alcohol solution, the UNIQUAC and Flory models were employed, and to calculate the activity of water in the alcohol-free water + salt solution, the Bromley and Pitzer models were employed. The predictions of the model were compared to the Delavar and Haghtalab, Mohammadi and Tohidi, and Hu-Lee-Sum (HLS) calculations. The new approach developed herein yielded accurate results for a databank of 613 data points of gas hydrate dissociations in the presence of alcohol solutions with average absolute deviations (AAD) of 0.79 K. For prediction of the gas hydrate dissociation temperature in the presence of aqueous salt solutions, the vdW-P + PR + Bromley model resulted in a notably enhanced accuracy with an AAD of 0.52 K for 1065 data points. Our research concludes with the superiority of this work, when the activity of water was used together with vdW-P + PR + UNIQUAC + Bromley. With an AAD of 0.68 K for 544 data points, the model reliably predicted gas hydrate dissociation temperatures in the presence of aqueous alcohol + salt solutions.

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Section: Activity Of Water In the Presence Of Alcoholsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Precise Thermodynamic Approach for Calculating Activity of Water in the Presence of Aqueous Alcohol + Salt Solutions and its Application to Gas Hydrate Dissociation Modeling

Keshavarzi,

Rasoolzadeh,

Nasrifar

2024

Ind. Eng. Chem. Res.

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show abstract

“…The Debye-Hückel theory [49] is based on the Poisson equation for electrical potential combined with the assumption of a Boltzmann distribution of ion density [49,72]. Due to it not having an analytical solution, it is linearized leading to the Debye-Hückel theory.…”

Section: Conventional Pitzer-debye-hückelmentioning

confidence: 99%

“…Both the Debye-Hückel equation and PDH term approach the Debye-Hückel limiting law at infinite dilution [73], but become increasingly inadequate to describe electrolyte systems with rising concentration [72]. Consequently, in the past the purely electrostatic terms were complemented by virial expansions [52,53], where interactions between ions and solvents are described by empirical parameters for the excess Gibbs free energy.…”

Section: Conventional Pitzer-debye-hückelmentioning

confidence: 99%