IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 1. Introduction, Be and Mg Alex De Visscher, Editor, Evaluatora) Department of Chemical and Petroleum Engineering, and Centre for Environmental Engineering Research and Education (CEERE), Schulich School of Engineering, University of Calgary, Calgary, AB, T2N 1N4 Canada Jan Vanderdeelen, Evaluatorb) Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium Erich Ko¨ nigsberger, Compilerc) School of Chemical and Mathematical Sciences, Murdoch University, Murdoch, WA, 6150, Australia Bulat R. Churagulov, Compiler Department of Chemistry, Moscow State University, Moscow, Russia Masami Ichikuni, Compiler and Makoto Tsurumi, Compiler Department of Environmental Chemistry, Tokyo Institute of Technology, Nagatsuda, Yokohama, Japan (Received 2 December 2011; accepted 6 December 2011; published online 27 March 2012) The alkaline earth carbonates are an important class of minerals. This volume compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1, the present paper, outlines the procedure adopted in this volume in detail, and presents the beryllium and magnesium carbonates. For the minerals magnesite (MgCO3), nesquehonite (MgCO3Á3H2O), and lansfordite (MgCO3Á5H2O), a critical evaluation is presented based on curve fits to empirical and=or thermodynamic models. Useful side products of the compilation and evaluation of the data outlined in the introduction are new relationships for the Henry constant of CO2 with Sechenov parameters, and for various equilibria in the aqueous phase including the 0 dissociation constants of CO2(aq) and the stability constant of the ion pair MCO3ðaqÞ (M ¼ alkaline earth metal). Thermodynamic data of the alkaline earth carbonates consist- ent with two thermodynamic model variants are proposed. The model variant that 2þ À describes the Mg ÀHCO3 ion interaction with Pitzer parameters was more consistent with the solubility data and with other thermodynamic data than the model variant that described the interaction with a stability constant. VC 2012 American Institute of Physics. [doi:10.1063/1.3675992] Key words: aqueous solution; beryllium carbonate; magnesium carbonate; solubility; thermodynamics. CONTENTS 1.2.4. Ambient CO2 mole fraction and altitude correction of total pressure. 5 1. Preface .................................... 3 1.3. Evaluations . .................... 6 1.1. Scope of the volume . ................... 3 1.3.1. Empirical equations for solubility . 6 1.2. Unit conversions for compilations ........ 3 1.3.2. Thermodynamic model for solubility 7 1.2.1. Density of pure water ............. 4 1.3.2.1. Model equations for open 1.2.2. Density of electrolyte solutions . 5 system . 8 1.2.3. Influence of dissolved gases on 1.3.2.2. Model equations for closed water density. ................... 5 system . 9 1.3.2.3. The Pitzer ion interaction formalism . 10 1.3.2.4. Some thoughts on the a) Electronic mail: [email protected]. calcium bicarbonate b)Electronic mail: [email protected]. c)Electronic mail: [email protected]. ion pair . 10 VC 2012 American Institute of Physics. 1.3.3. Thermodynamic data . 11 0047-2689/2012/41(1)/013105/67/$47.00013105-1 J. Phys. Chem. Ref. Data, Vol. 41, No. 1, 2012 Downloaded 27 Mar 2012 to 132.163.193.247. Redistribution subject to AIP license or copyright; see http://jpcrd.aip.org/about/rights_and_permissions 013105-2 DE VISSCHER ET AL. 1.3.3.1. Solubility of CO2.......... 11 3. Sechenov coefficients for CO2 in various 34 1.3.3.2. Salting out of CO2......... 12 electrolyte solutions, together with fitted 1.3.3.3. Fugacity of the gas phase. 13 values. .................... 12 1.3.3.4. Dissociation constants of 4. Single-ion Sechenov coefficients and Pitzer k carbonic acid ............. 15 parameters for CO2 in electrolytes, with 1.3.3.5. Ionization constant of temperature dependence .................... 13 water . ................... 18 5. Enthalpy and entropy of the first dissociation 1.3.3.6. Metal-carbonate ion of CO2 at 298.15 K estimated from different pairing ................... 18 sources . .................... 15 1.3.3.7. Other ion pairs ............ 23 6. Values of Àlg(K1) from the Harned and 1.3.4. Independent thermodynamic data . 25 Davis50 experiments obtained with different 1.3.5. Solubility in salt solutions: a SIT data analysis techniques .................... 17 approach ........................ 26 7. Enthalpy and entropy of the second 1.4. Remaining issues....................... 26 dissociation of CO2 at 298.15 K estimated 2. Solubility of Beryllium Carbonate ............ 27 from different sources . .................... 18 2.1. Critical evaluation of the solubility of 8. Stability constants of alkaline earth beryllium carbonate in aqueous systems . 27 bicarbonate ion pairs . .................... 19 2.2. Data for the solubility of beryllium 9. Stability constants of alkaline earth carbonate carbonate in aqueous systems ............ 27 ion pairs. .................... 21 3. Solubility of Magnesium Carbonate . ........ 27 10. Pitzer parameters for M(HCO3)2 ............. 22 3.1. Critical evaluation of the solubility of 11. Stability constants of alkaline earth hydroxide magnesium carbonate in aqueous ion pairs. .................... 24 systems ............................... 27 12. Single-electrolyte Pitzer parameters for 3.1.1. Overview of solubility data ........ 28 M(OH)2 .................................. 25 3.1.2. Analytical methods used for 13. Two-electrolyte ion interactions . 25 dissolved magnesium 14. Overview of magnesium carbonate solubility determination . ................... 30 data in aqueous systems .................... 28 3.1.3. Magnesite ....................... 30 15. Data collected for the evaluation of the 3.1.3.1. MgCO3 þ H2O þ CO2 ...... 30 solubility of magnesite in the system 3.1.3.2. MgCO3 þ H2O þ CO2 MgCO3 þ H2O þ CO2 ...................... 31 þ NaCl . ............... 33 16. Evaluation of magnesite solubility in the 3.1.3.3. MgCO3 þ H2O............ 33 system MgCO3 þ H2O þ CO2................ 32 3.1.3.4. MgCO3 þ H2O þ salt. 34 17. Data collected for the evaluation of the 3.1.4. Nesquehonite. ................... 35 solubility of MgCO3 in the system 3.1.4.1. MgCO3Á3H2O þ H2O MgCO3 þ H2O þ CO2 þ NaCl . 33 þ CO2 ................... 35 18. Data collected for the evaluation of the 3.1.4.2. MgCO3Á3H2O þ H2O þ CO2 solubility of magnesite in the system þ salt . ................... 39 MgCO3 þ H2O ............................ 33 3.1.4.3. MgCO3Á3H2O þ H2O....... 39 19. Comparison of magnesite solubility in the 3.1.4.4. MgCO3Á3H2O þ H2O system MgCO3 þ H2O with model þ salt . ................... 42 predictions. .................... 34 3.1.5. Lansfordite . ................... 42 20. Data collected for the evaluation of the 3.1.5.1. MgCO3Á5H2O þ H2O solubility of MgCO3 in the system þ CO2 ................... 42 MgCO3 þ H2O þ NaCl . .................... 34 3.1.6. Conclusion....................... 44 21. Data collected for the evaluation of the 3.2. Data for the solubility of magnesium solubility of MgCO3 in the system carbonate in aqueous systems ............ 45 MgCO3 þ H2O þ Na2SO4 ................... 34 Acknowledgments .......................... 66 22. Data collected for the evaluation of the 4. References................................. 66 solubility of MgCO3 in the system MgCO3 þ H2O þ Na2CO3 ................... 35 List of Tables 23. Data collected for the evaluation of the 1. Thermodynamic properties of the dissolution solubility of MgCO3 in the system of CO2 at 25 C derived from different semi- MgCO3 þ H2O þ NaNO3.................... 35 empirical equations ........................ 11 24. Data collected for the evaluation of the 2. Henry constant of CO2 predicted in this study solubility of MgCO3 in the system 32 and by Crovetto ......................... 12 MgCO3 þ H2O þ MgCl2 .................... 35 J. Phys. Chem. Ref. Data, Vol. 41, No. 1, 2012 Downloaded 27 Mar 2012 to 132.163.193.247. Redistribution subject to AIP license or copyright; see http://jpcrd.aip.org/about/rights_and_permissions IUPAC-NIST SOLUBILITY DATA SERIES. 95-1 013105-3 25. Data collected for the evaluation of the system 1. Preface MgCO3Á3H2O þ H2O þ CO2, and fit with empirical model ........................... 36 1.1. Scope of the volume 26. Evaluation of nesquehonite solubility in the Solubilities of alkaline earth metal carbonates in water system MgCO3Á3H2O þ H2O þ CO2 .......... 40 and aqueous solutions are of interest in many areas such as 27. Data collected for the evaluation of the biology, geology, hydrology, medicine, and environmental solubility of MgCO3 in the system sciences. Of particular significance is the interaction between MgCO3Á3H2O þ H2O þ CO2 þ Na2CO3 ....... 42 alkaline earth metal carbonates and carbon dioxide during 28. Data collected for the evaluation of the CO2 storage in underground aquifers. solubility of nesquehonite in the system This volume contains compilations and evaluations of the MgCO3Á3H2O þ H2O....................... 42 solubilities of the alkaline earth carbonates in water and sim- 29. Comparison of nesquehonite solubility in the ple electrolyte solutions. Solid phases containing mixed car- system MgCO3Á3H2O þ H2O with model bonates or mixed carbonates and hydroxides, solubilities in predictions................................ 42 mixed or non-aqueous solvents, solubilities