Coupled Phase Diagram/Thermodynamic Analysis of the Nine Common‐Ion Binary Systems Involving the Carbonates and Sulfates of Lithium, Sodium, and Potassium

Abstract

2941electrochemica ! transport that occurs during EVD is similar to the phenomena of oxygen semipermeability wherein electrons migrate from the low oxygen partial pressure side to the high oxygen partial pressure side and oxygen ions migrate in the reverse direction maintaining electroneutrality. AcknowledgmentsThe authors would like to acknowledge the dedicated efforts of G. R. Folser and J.A. Fraino in conducting the EVD experiments and Mrs. J. A. Radford for her patience in typing the manuscript. The help of T. A. Manion in preparing the metallographic mounts and R. W. Palmquist in analyzing the samples with electron microprobe is greatly appreciated. ABSTRACTThe thermodynamic properties and phase diagrams of the nine common-ion binary systems of alkali carbonates' and sulfates have been critically evaluated by the technique of computer-assisted simultaneous optimization. Coefficients of series expansions for the excess thermodynamic properties of all phases have been found which can be used to reproduce the thermodynamic properties and to calculate the phase diagrams within experimental error limits. Henrian activity coefficients of dilute solid solutions and Gibbs energies of formation of compounds have also been determined. The resultant calculated thermodynamic properties and phase diagrams are self-consistent, and represent the best estimates which can be made based on currently available data. A consistent set of values for the thermodynamic properties of the pure salts has also been adopted, and some thermodynamic properties of the pure alkali carbonates and sulfates have been revised.Molten salt systems involving carbonates and sulfates are of importance in hot corrosion, in electrochemical cells such as the molten carbonate fuel cell, and in many chemical and metallurgical applications. The present article reports critical, coupled evaluations of phase diagram and thermodynamic data for the nine common-ion binary sysl Permanent address: Sangster Research Laboratories, Montreal, Quebec, Canada H3G 2A4.tems involving the carbonates and sulfates of lithium, sodium, and potassium.A complete literature survey has been carried out for the nine systems treated in this article, for both phase diagram and thermodynamic data. Coefficients of Gibbs energy expressions which represent the thermodynamic and phase diagram data within experimental error have been found by computer optimization. This calculation uncovers discrepancies among the data and generates analytical ex-) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.171.57.189 Downloaded on 2015-06-26 to IP

Thermodynamic evaluation and optimization of the (Na2CO3+ Na2SO4+ Na2S + K2CO3+ K2SO4+ K2S) system

“…The thermodynamic data for solid and liquid sulphides and sulphates were taken from Lindberg et al [2,3]. The thermodynamic data for Na 2 CO 3 and K 2 CO 3 were taken from the NIST-JANAF compilations [5], but the melting temperature of Na 2 CO 3 and the temperatures and enthalpies of (solid + solid) transitions of Na 2 CO 3 and K 2 CO 3 were based on the adopted values from the thermodynamic evaluation of Dessureault et al [6]. The C p -functions of the solid carbonates were taken from the FACT database [4], where the C p -functions were fitted to the tabulated data in the NIST-JANAF compilations.…”

“…Dessureault et al [6] performed a thermodynamic analysis of the (Na 2 CO 3 + Na 2 SO 4 ) system, where it was assumed that the liquid phase is an ideal solution, and where the thermodynamic solution properties of the hexagonal solid solution were derived from the solidus and liquidus data. However, the study by Mukhopadhyay and Jacob [24] on the thermodynamic properties of the hexagonal solid solution was published at a later stage, and therefore it was not included in the thermodynamic assessment by Dessureault et al [6].…”

Релаксация Колебательно-Возбужденных Состояний В Твердых Бинарных Системах Карбонат--Сульфат

“…• C -гексагональная γ-модификация пространственной груп-пы P6 3 mc [15,17,18]. Температура плавления равна T m = 850−858…”

Thermodynamic evaluation and optimization of the (Na2SO4+ K2SO4+ Na2S2O7+ K2S2O7) system

“…Experimental points (s) are from [47]. [55,56]. The system was modelled using sublattice models [57,58] and optimized model coefficients were determined with a random (Bragg-Williams) configurational entropy.…”

“…Dessureault et al [55], and Sangster and Pelton [59] have made detailed reviews of the experimental determinations of the (Na 2 SO 4 + K 2 SO 4 ) phase diagram. The system has several solid solutions and has a minimum in the solidus and the liquidus.…”