A New Pitzer Parameterization for the Binary NaOH–H2O and Ternary NaOH–NaCl–H2O and NaOH–LiOH–H2O Systems up to NaOH Solid Salt Saturation, from 273.15 to 523.15 K and at Saturated Vapor Pressure

Abstract

This paper presents a new set of Pitzer ion interaction model parameters for the binary NaOH-H 2 O system for concentrations up to over 30 molÁkg -1 and temperatures ranging from 273.15 to 523.15 K. Assuming that the electrolyte is only partially dissociated, the model requires the adjustment of (i) the three classical binary interaction parameters b (0) , b (1) and C / , (ii) the equilibrium constant of formation of the aqueous complex NaOH 0 (aq), and iii) one binary (k NaOH/NaOH ) and one ternary (f NaOH=Na þ =OH À ) interaction parameter. This approach, which provides much better results than the approach of treating NaOH as a fully dissociated electrolyte, was chosen to extend the description of the system to high temperatures and high concentrations. The temperature functions of the solubility products of anhydrous NaOH(cr) and five hydrated salts, NaOHÁnH 2 O(cr) (where n = 1, 2, 3.11, 3.5, 4a), were determined. In order to evaluate the quality of the new set of Electronic supplementary material The online version of this article (parameters, several tests were run on various properties using various literature data. These include the boiling point elevation in the NaOH-H 2 O system and the phase diagrams of the two ternary systems NaOH-NaCl-H 2 O and NaOH-LiOH-H 2 O. Interaction parameters for the two related binary systems NaCl-H 2 O and LiOH-H 2 O were taken from previous studies. To ensure consistency, four new mixing parameters were revised (f Na þ =Cl À =NaOH and W Cl À =OH À =Na þ for the ternary system NaOH-NaCl-H 2 O and k Li þ =NaOH and W OH À =Na þ =Li þ for the ternary system NaOH-LiOH-H 2 O). Consistent with Pitzer's equations, our new set of parameters can be used to satisfactorily describe the quaternary Na ? -Li ? -Cl --OH --H 2 O system to very high concentrations and temperatures.

Decarbonisation of calcium carbonate at atmospheric temperatures and pressures, with simultaneous CO2 capture, through production of sodium carbonate

“…At atmospheric pressure, this reaction can be carried out at temperatures up to the boiling point of the NaOH solution; B170 1C. 22 At higher pressures, where the aqueous solution is stable, the reaction may also occur at higher temperatures. In the flowsheets, all UOs that may require thermal energy input are highlighted pink.…”

Thermodynamic Modeling of Aqueous Electrolyte Systems: Current Status

“…It is well-known, for example, that the Pitzer equations are much less robust than SIT (ref , p 365). Pitzer parameters determined in sets are prone to subsequent inconsistencies and ongoing revision–see ref for instance. Fortunately, these and other limitations are now becoming better understood .…”

Experimental Data and Modeling of Solution Density and Heat Capacity in the Na–K–Ca–Mg–Cl–H2O System up to 353.15 K and 5 mol·kg–1 Ionic Strength

“…35−37 Others consider the partial dissociation of electrolytes, adding specific interactions between neutral and neutral species or neutral and ionic species. 25,26,38 For a system containing an undefined number of both neutral and ionic solute species, the excess Gibbs energy is described by the expression given by Clegg and Whitfield 39 and Felmy and Weare. 40 In this study, all the electrolytes were considered totally dissociated and, because the only anion was chloride (Cl − ), the Gibbs excess energy (G ex ) was computed using eq 3:…”