Heat capacities of aqueous sodium hydroxide/aluminate mixtures and prediction of the solubility constant of boehmite up to 300°C

Schrödle, Simon; Königsberger, Erich; May, Peter M.; Hefter, Glenn

doi:10.1016/j.gca.2010.01.002

Cited by 18 publications

(12 citation statements)

References 32 publications

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“…Interestingly, the very small Na 2 Ox(s) solubilities measured vary systematically when NaClO 4 (aq) is replaced by NaOH(aq) at I c ≈ 7.0 M. It is also noteworthy that the solubilities of Na 2 Ox(s) in the industrially relevant caustic aluminate solutions are consistent with their [Na + ], at least at T = 298.15 K (Table , Figure ). In other words, the solubility of Na 2 Ox(s) in such mixtures is dominated by a simple common ion effect, which is supported by our findings for other thermodynamic properties of NaOH(aq)/NaAl(OH) 4 (aq) mixtures. − …”

Section: Resultssupporting

confidence: 83%

Solubility of Sodium Oxalate in Concentrated Electrolyte Solutions

et al. 2018

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The solubility of solid sodium oxalate (Na2Ox) has been measured in a variety of concentrated aqueous electrolyte solutions at T = 298.15, 323.15, and 343.15 K by titration of dissolved oxalate with permanganate. The electrolyte solutions studied (not necessarily at all temperatures) were NaCl, NaClO4, NaOH, LiCl, KCl, Me4NCl, and KOH at concentrations ranging from approximately 0.5 mol·kg–1 to at least 5 mol·kg–1. Where comparisons were possible, the present results were in excellent agreement with literature data. The solubility of Na2Ox(s) decreased markedly with increasing concentrations of Na+(aq), due to the common ion effect. This decrease was almost independent of the electrolyte anion. A number of ternary mixtures of these electrolytes were also investigated at constant ionic strength. Consistent with the binary mixtures, the solubility of Na2Ox(s) showed almost no dependence on solution composition at constant Na+(aq) concentrations. Solubilities in non-Na+ media, with the exception of Me4NCl, showed small but regular increases with increasing concentration of added electrolyte, probably reflecting activity coefficient variations. The solubility data in certain Na+-containing media could be correlated accurately at all temperatures and concentrations using a relatively simple Pitzer model with interaction parameters for Na2Ox(aq) assumed to be identical to those available in the literature for Na2SO4(aq).

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Section: Resultssupporting

confidence: 83%

Solubility of Sodium Oxalate in Concentrated Electrolyte Solutions

et al. 2018

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“…Furthermore, the temperature is raised and lowered at a very consistent, slow rate, which makes the C p measurement more accurate. The C80 calorimeter has found an application in the precise determination of heat capacities of different materials [19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Evolution of Specific Heat Capacity with Temperature for Typical Supports Used for Heterogeneous Catalysts

Wang

Estel

et al. 2020

Processes

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Heterogeneous catalysts are widely used in the chemical industry. Compared with homogeneous catalysts, they can be easily separated from the reaction mixture. To design and optimize an efficient and safe chemical process one needs to calculate the energy balance, implying the need for knowledge of the catalyst’s specific heat capacity. Such values are typically not reported in the literature, especially not the temperature dependence. To fill this gap in knowledge, the specific heat capacities of commonly utilized heterogeneous catalytic supports were measured at different temperatures in a Tian–Calvet calorimeter. The following materials were tested: activated carbon, aluminum oxide, amberlite IR120 (H-form), H-Beta-25, H-Beta-38, H-Y-60, H-ZSM-5-23, H-ZSM-5-280, silicon dioxide, titanium dioxide, and zeolite 13X. Polynomial expressions were successfully fitted to the experimental data.

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“…[32], data for the "solidus" line suggest that Al-goethites can be modelled as dilute solid solutions of goethite with a hypothetical "AlOOH" end member (Fig. 3), whose solubility constant is significantly greater than those of diaspore, boehmite, and gibbsite, as calculated from thermodynamic data [33,34]. This dilute solid-solution model is supported by the fact that diaspore does not normally precipitate from aqueous solution under diagenetic conditions [35].…”

Section: "Primary Saturation" and Hypothetical End-membersmentioning

confidence: 87%

Solid-solute phase equilibria in aqueous solution: Fundamentals and applications

Königsberger¹

2013

Pure and Applied Chemistry

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Carbonates 1 Phase Transitions 1 Solutions 1 ThermodynamicsSolid binary carbonate phases often dissolve congruently in aqueous media, even when they are not stable under the prevailing conditions. From the thermodynamic point of view these dissolution reactions lead to a metastable equilibrium with fixed composition, when neither diffusion in the solid state nor recrystallization from the solution occurs. The solubility of natural huntite, CaMg3(C03)4, was studied potentiometrically at 50°C and I = 3.0 mol kg-' (Na)C104. Since it dissolved congruently the solubility constant log * . Amazingly enough phase equilibria of solid mixtures in aqueous media have seldom been studied in detail, although the corresponding reactions play an important role in geochemistry as well as in hydrometallurgy. Lippmann [S] described the aqueous solubility of binary mineral systems using the total solubility product and the mole fraction as master variables of phase diagrams. These diagrams are based on the solubility products of the pure end members and a simple electrostatic mixing model, but have in most cases not been verified experimentally. One of the reasons for this lack of scientific activity in an obviously interesting field is certainly the fact that the rates of heterogeneous ionic reactions are rather slow at temperatures between the freezing and the boiling point of water at ordinary pressure, and differing results have been obtained when equilibrium was approached from undersaturation and supersaturation respectively. A pertinent example are the contradictory results for the solubilities of magnesian calcites obtained by different research groups [6].In this paper the thermodynamic formalism for solid-solute ionic equilibria in the system CaC03 -MgC03 -H,O is presented with particular emphasis on phase transitions without diffusion in the solid state [7]. It is applied for the determination of the solubility constant, phase equilibria and free enthalpy of formation of huntite, CaMg3(CO&. This mineral occurs naturally although its decomposition into dolomite, CaMg(CO&, and magnesite, MgC03, is thermodynamically favoured.

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Heat capacities of aqueous sodium hydroxide/aluminate mixtures and prediction of the solubility constant of boehmite up to 300°C

Cited by 18 publications

References 32 publications

Solubility of Sodium Oxalate in Concentrated Electrolyte Solutions

Solubility of Sodium Oxalate in Concentrated Electrolyte Solutions

Evolution of Specific Heat Capacity with Temperature for Typical Supports Used for Heterogeneous Catalysts

Solid-solute phase equilibria in aqueous solution: Fundamentals and applications

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