Isopiestic measurements on the system water-sodium chloride-magnesium chloride at 25.deg.

Platford, R. F.

doi:10.1021/j100858a019

Cited by 49 publications

(27 citation statements)

References 3 publications

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“…It is unclear to us why Platford's (1968) parameterization of the Scatchard model (using his isopiestic data for NaCl(aq) + MgCl 2 (aq) mixtures) yields results that are close to the Rard and Miller values for γ NaCl but not those for γ MgCl 2 . Essentially opposite behaviour is observed for the Harned-rule model of Wu et al (1968), which is close to Rard and Miller's (1987) prediction for γ MgCl 2 but not for γ NaCl .…”

Section: (Crosses)mentioning

confidence: 90%

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Aqueous electrolyte solution modelling: Some limitations of the Pitzer equations

Rowland

Königsberger

Hefter

et al. 2015

Applied Geochemistry

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Despite intense efforts, general thermodynamic modelling of aqueous electrolyte solutions still presents a difficult challenge, with no obvious method of choice. Even though the Pitzer equations seemingly provide a well-established theoretical framework applicable to many chemical systems over a wide range of temperatures and pressures, they are not as widely adopted as their early promise might have suggested. This is strikingly illustrated by the simultaneous appearance in the literature of numerous, different (and potentially incompatible) Pitzer models alongside a proliferation of alternative theoretical approaches with inferior capabilities.To better understand this problem, the ability of the Pitzer equations to represent the physicochemical properties of aqueous solutions has been systematically investigated for exemplar electrolyte systems. Pitzer ion-interaction parameters have been calculated for selected systems by least-squares regression analysis of published solution data for activity coefficients, osmotic coefficients, relative enthalpies, heat capacities, volumes and densities to high temperatures and pressures. Although satisfactory fits can be achieved when the ranges of conditions are carefully chosen and when sufficient data are available to constrain the regression, the fits obtained tend otherwise to be unsatisfactory. The Pitzer equations do not cope well with gaps and other deficiencies in the regressed data. Profound difficulties, poorly recognized hitherto, can also arise because of variation in the sensitivity of the Pitzer functions to values for different physicochemical properties when these are combined. Given the dimensionality of numerous related thermodynamic properties, all changing as functions of composition, temperature and pressure, these problems are difficult to detect, let alone address, especially in multicomponent systems. The growing practice of improving fits simply by adding basis functions (thereby increasing the number of adjustable parameters) should be deprecated because it increases the likelihood of error propagation, introduces subjectivity, makes independent verification difficult and has deleterious implications for both automated data processing and for consistency between thermodynamic models.

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Section: (Crosses)mentioning

confidence: 90%

“…9b). (Platford, 1968) (squares), Scatchard (Platford, 1968) (circles), Pitzer (θ = ψ = 0) (Rard and Miller, 1987) (triangles), Scatchard (Rard and Miller, 1987) …”

Section: Case Study D: General Regression Of Disparate Literature Datmentioning

confidence: 99%

Aqueous electrolyte solution modelling: Some limitations of the Pitzer equations

Rowland

Königsberger

Hefter

et al. 2015

Applied Geochemistry

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“…The data included in the model parameter evaluations are summarized in Table 5. Plotting symbols: , Rard and Miller [39]; , Rard and Miller [30]; , Platford [13]; , Wu et al [21]; , Gibbard and Gossmann [40]; , Padova and Saad [16]; , Stokes [37]; , Robinson and Stokes [36]; , Kuschel and Seidel [17]; ! ", Miladinović, et al [18]; , this study (Table 1); , Frolov et al [38]; , Saad et al [24]; , Robinson and Bower [19].…”

Section: Figmentioning

confidence: 99%

“…The studies of Rard and Miller [39] and Stokes [37] include isopiestic data at higher molalities that were not analyzed because they occur above the upper molality limit of our model; the listed number of data points is only for those solutions with m ≤ 4.0251 mol·kg -1 that were considered in the model parameter evaluations. Osmotic coefficients were also determined at higher molalities in the investigations of Robinson and Bower [19] and Gibbard and Gossman [40], and at lower molalities by Platford [13], but they are not included here for reasons described by Rard and Miller [39]. b These are the relative weights given to the individual osmotic coefficients calculated from the reported isopiestic molalities; the numbers given in parentheses are the numbers of osmotic coefficients from that study given zero weight in the model parameter evaluations, based on a 2.5σ(φ) rejection criterion.…”

Section: Figmentioning

confidence: 99%

Isopiestic Investigation of the Osmotic and Activity Coefficients of {yMgCl2+(1−y)MgSO4}(aq) and the Osmotic Coefficients of Na2SO4⋅MgSO4(aq) at 298.15 K

et al. 2008

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Isopiestic vapor pressure measurements were made for {yMgCl 2 + (1 -y)MgSO 4 }(aq) solutions with MgCl 2 ionic strength fractions of y = (0, 0.1997, 0.3989, 0.5992, 0.8008, and 1) at the temperature 298.15 K, using KCl(aq) as the reference standard.These measurements for the mixtures cover the ionic strength range I = 0.9794 to 9.4318 mol·kg -1 . In addition, isopiestic measurements were made with NaCl(aq) as reference

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“…This is related to the poor representation of osmotic coefficients of LiNO, solutions which was mentioned above. LiCI-NaCI LiCI-BaCI, NaCI-CaCI, NaCI-CsCI NaCI-BaCI2 CsC1-BaClZ KCI-CaCL KCI-BaCI, NaC1-KCI KCI-SrCI: MgCI2-CaCl2 NaCI-SrCI2 NaC1-MgCI, NaCI-NaBr NaBr-KBr KCI-KBr NaCI-NaNO, KCI-KNO, NaN0,-KNO, LiN0,-NaNO, Na2S04-MgS0, Li,S04-Cs2S04 Na2S04-Cs2S04 Na2SO4-Rb2SO4 LiZS04-Rb2S04 Li,S04-Na2S04 Li,S04-K,S04 Robinson and Bower (1966a); (d) Robinson (1952); (e) Rard and Miller (1982); (f) Robinson and Bower (1965); (g) Robinson and Covington (1968); (h) Reilly et al (1971); (i) Robinson (1961); 6 ) Downes (1974); (k) Robinson and Bower (1966b); (I) Macaskill et al (1978); (m) Platford (1968); (n) Rard and Miller (1987); (0) Covington et al (1968); (p) Robinson (1953); (4) Padova and Saad (1977); (r) Bezboruah et al (1970); (s) Rard and Miller (1981); (1) Filipov et al (1987); (u) Filipov et al (1989).…”

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confidence: 99%

Representation of excess properties of electrolyte solutions using a new equation of state

Fürst¹,

Renon²

1993

AIChE Journal

163

119

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International audienceA new equation of state for electrolyte solutions has been developed from an expression of the Helmholtz free energy containing a nonelectrolyte part and a part relative to ions. The nonelectrolyte part is taken from the equations of state (EOS) of Schwartzentruber et al. (1989). The ionic part is composed of an MSA long-range term to account for electrostatic interactions and a short-range interaction term specific to ions. Using correlations between parameters and experimental ionic diameters, the model reduces to a one-parameter model. It has been applied to numerous strong electrolyte systems and extended to ternary systems to test its predictability without mixing parameters for ions. Its results compare well to the results reported for other one-parameter models (electrolyte EOS). Furthermore, it was found that the cation-anion interaction parameter could also be correlated to experimental ionic diameters. Then, the osmotic coefficients of 28 alkaline and alkaline-earth halide systems may be represented with a root mean square relative deviation of 2.9% using only six correlation parameters. This result has been extended to other systems, with the conclusion that the model with all parameters correlated may also be applied to systems other than halide solutions. The resulting model is predictive. The quality of the prediction was tested by determining osmotic coefficients relative to six systems without any parameter adjustment. The deviations of the predicted values range from 2.0 to 5.4%. The quality of the representation of mixed salts systems without mixing parameters was evaluated using experimental osmotic coefficients of 30 ternary systems

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Isopiestic measurements on the system water-sodium chloride-magnesium chloride at 25.deg.

Cited by 49 publications

References 3 publications

Aqueous electrolyte solution modelling: Some limitations of the Pitzer equations

Aqueous electrolyte solution modelling: Some limitations of the Pitzer equations

Isopiestic Investigation of the Osmotic and Activity Coefficients of {yMgCl2+(1−y)MgSO4}(aq) and the Osmotic Coefficients of Na2SO4⋅MgSO4(aq) at 298.15 K

Representation of excess properties of electrolyte solutions using a new equation of state

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