Extended Specific Ion Theory (ESIT): Theoretical development and application to Harned’s rule

Visscher, Alex De

doi:10.1007/s10953-022-01152-4

Cited by 2 publications

(3 citation statements)

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“…It was found in a previous study that the SIT model expanded with a second-order term tends to be more accurate in a modi ed molality scale m' expressed in mol per kg solution than in the standard molality scale m (mol per kg water) [13]. This is because at high molality, (m > 15 mol kg − 1 ) small changes of the composition lead to large changes of the molality.…”

Section: Modi Ed Molalitymentioning

confidence: 93%

“…The Extended Speci c Ion theory (ESIT) model was derived by De Visscher [13]. The excess Gibbs free energy is given by: 1 For the sake of generality, the parameter with value 1.5 will be indicated more generally with the letter B:…”

Section: Extended Speci C Ion Theorymentioning

confidence: 99%

“…In a previous study, an extension of the SIT model was proposed [13]. The extension signi cantly improved the accuracy of the model without signi cantly affecting the complexity.…”

Section: Introductionmentioning

confidence: 99%

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Incorporating Ion Pairing in an Extended Specific Ion Theory: 2-2 Electrolytes

Visscher¹,

Chavoshpoor²

2022

Preprint

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The specific ion theory (SIT) is a relatively simple model for the description of activity coefficients of ions in electrolyte solutions. However, the SIT model does not account for ion pairing, a phenomenon that is pronounced in 2–2 electrolytes. In this work, a recent extension of the SIT model is further extended to account for ion pairing. The model extension is tested with reported data for BeSO2, MgSO4, MnSO4, NiSO4, CuSO4, ZnSO4, and CdSO4. The standard error of the fit is typically around 1%. To get this accuracy in model fits of the activity coefficients that are consistent with literature data of the MgSO40 ion pair concentration, it was necessary to work in a modified molality scale and to reduce the SIT parameter B from 1.5 to 1.2. The drawback of this choice is that a value of B equal to 1.2 leads to worse predictions of the activity coefficients of 1–1 electrolytes. It is concluded that not accounting for ion pairing in 2–2 electrolytes leads to overestimations of the ionic strength of up to 30% and leads to overestimations of the Debye-Huckel term for the activity coefficient of 2–2 electrolytes by up to 20%.

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Section: Modi Ed Molalitymentioning

confidence: 93%

Section: Extended Speci C Ion Theorymentioning

confidence: 99%