Electrochemical method for the solubility and dissolution of solid compounds. Some thermodynamic properties of the system Al(OH)3-NaOH-H2O

Berecz, E.; Szita, L.

doi:10.1016/0013-4686(70)80061-5

Cited by 7 publications

(6 citation statements)

References 11 publications

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“…2). The data of Berecz and Szita (1970) are in close agreement with other studies at lower temperatures, but show systematically higher solubilities at 50-60 °C, and therefore the dataset was not included. The experiments of Apps (1970) in dilute NaOH solutions show a large scatter and were discarded because of a suspected contamination of the run materials with bayerite (Apps et al, 1988).…”

Section: Gibbsite Solubilitysupporting

confidence: 78%

Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl

Miron

Wagner

Kulik

et al. 2016

Geochimica et Cosmochimica Acta

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A large amount of critically evaluated experimental data on mineral solubility, covering the entire Na-K-Al-Si-O-H-Cl system over wide ranges in temperature and pressure, was used to simultaneously refine the standard state Gibbs energies of aqueous ions and complexes in the framework of the revised Helgeson-Kirkham-Flowers equation of state. The thermodynamic properties of the solubility-controlling minerals were adopted from the internally consistent dataset of Holland and Powell (2002; Thermocalc dataset ds55). The global optimization of Gibbs energies of aqueous species, performed with the GEMSFITS code (Miron et al., 2015), was set up in such a way that the association equilibria for ion pairs and complexes, independently derived from conductance and potentiometric data, are always maintained. This was achieved by introducing reaction constraints into the parameter optimization that adjust Gibbs energies of complexes by their respective Gibbs energy effects of reaction, whenever the Gibbs energies of reactant species (ions) are changed. The optimized thermodynamic dataset is reported with confidence intervals for all parameters evaluated by Monte Carlo trial calculations. The new thermodynamic dataset is shown to reproduce all available fluid-mineral phase equilibria and mineral solubility data with good accuracy and precision over wide ranges in temperature (25 to 800°C), pressure (1 bar to 5 kbar) and composition (salt concentrations up to 5 molal). The global data optimization process adopted in this study can be readily repeated any time when extensions to new chemical elements and species are needed, when new experimental data become available, or when a different aqueous activity model or equation of state should be used. This work serves as a proof of concept that our optimization strategy is feasible and successful in generating a thermodynamic dataset reproducing all fluidmineral and aqueous speciation equilibria in the Na-K-Al-Si-O-H-Cl system within their experimental uncertainties. The new dataset resolves the long-standing discrepancies between thermodynamic data of minerals and those of aqueous ions and complexes, by achieving an astonishing degree of consistency between a large number of fluid-mineral equilibrium data. All of this at the expense of changing the standard state properties of aqueous species, manly the Gibbs energy of formation. Using the same strategy, the core dataset for the system Na-K-Al-Si-O-H-Cl can be extended with additional rock-forming elements such as Ca, Mg, Fe, Mn, Ti, S, C, B. In future, the standard-state properties of minerals and aqueous species should be simultaneously optimized, to create the next-generation of fully internally consistent data for fluid-mineral equilibria. Although we employ the widely used HKF equations for this study, the same computational approach can be readily applied to any other speciation-based equation of state for multicomponent aqueous solutions.

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Section: Gibbsite Solubilitysupporting

confidence: 78%

Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl

Miron

Wagner

Kulik

et al. 2016

Geochimica et Cosmochimica Acta

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“…9 we have plotted log tr versus log × II~bbsite. The supersaturations with respect to gibbsite were calculated from published data by different investigators (9)(10)(11)(12). The results of some experiments at 62.5 and 90°C are also included in this figure.…”

Section: Relaxation Behavior Of the Precipitating Systemmentioning

confidence: 99%

“…[9] we then deduce that ~* = ~" v 2/~. [10] In order to derive values for ~* and In × rb(T) the solubility products (Ksv) of the various phases must be known. A value of 0.7 has been estimated at 25°C (9, 12) for pKsp(bay) = -log(aAl(On~/aom).…”

Section: Tr* = (K/~f-b)t/~1/2mentioning

confidence: 99%

“…A value of 0.7 has been estimated at 25°C (9, 12) for pKsp(bay) = -log(aAl(On~/aom). To evaluate pK~p(bay) at higher temperatures we assume this phase to have the same temperature dependence as gibbsite (9)(10)(11). This means that AH ° for the reaction Al(OH)4(aq) AI(OH)3(s) + OH-(aq) must be approxJmately the same for bayerite and gibbsite--a reasonable assumption.…”

Section: Tr* = (K/~f-b)t/~1/2mentioning

confidence: 99%

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Precipitation from supersaturated aluminate solutions. II. Role of temperature

Straten¹,

Bruyn²

1984

Journal of Colloid and Interface Science

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“…However, the chemical characterization of these solutions is difficult because they are chemically aggressive and, like all highly concentrated electrolyte solutions, hard to deal with both theoretically and experimentally. Indeed, many of the most powerful analytical techniques for studying chemical speciation in solution such as potentiometry − and NMR, − UV−Vis, − and IR/ Raman ,,− spectroscopies have had limited success in providing useful information about these solutions, as evidenced by a striking lack of agreement between them …”

Section: Introductionmentioning

confidence: 99%

Structure of Aqueous Sodium Aluminate Solutions: A Solution X-ray Diffraction Study

et al. 1998

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A structural analysis of six alkaline sodium aluminate aqueous solutions by the X-ray diffraction method is reported. On average, each Al atom is surrounded by four oxygens, indicative of the predominance of Al(OH) 4 -(aq) in these solutions. Detailed least-squares fitting indicates that a significant contraction of the Al-O distances occurs with increasing aluminate concentration, from 1.80 Å at 2 M to 1.74 Å at 6 M Al-(OH) 3 in 8 M NaOH. The local structure has been described by models that have separate hydrated ions in the most dilute aluminate solution but contact sodium aluminate ion pairs in the most concentrated solution. The hydration number of the sodium ion decreases with increasing concentration, but the overall coordination number appears to be unchanged by the ion pair formation. An extensive rearrangement in the hydrogenbonded network of bulk water also occurs as the aluminum concentration rises, with the appearance of new diffraction distances at 3.3 and 3.9 Å. A gradual appearance and disappearance of shorter hydrogen bonds between first neighboring O atoms is observed. The data are consistent with the occurrence of oligomeric aluminate species but are not conclusive within the limits of the experimental error.

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Electrochemical method for the solubility and dissolution of solid compounds. Some thermodynamic properties of the system Al(OH)3-NaOH-H2O

Cited by 7 publications

References 11 publications

Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl

Internally consistent thermodynamic data for aqueous species in the system Na–K–Al–Si–O–H–Cl

Precipitation from supersaturated aluminate solutions. II. Role of temperature

Structure of Aqueous Sodium Aluminate Solutions: A Solution X-ray Diffraction Study

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