The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.

Chemical Thermodynamics of Aqueous Electrolyte Systems for Industrial and Environmental Applications

Justin Salminen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Chemical Technology for public examination and debate in Komppa Auditorium at Helsinki University of Technology (Espoo, Finland) on the 20th of March, 2004, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-6936-8)   [549 KB]
Dissertation is also available in print (ISBN 951-22-6926-0)


This thesis consists of studies of chemical thermodynamics of aqueous electrolytes for industrial and environmental applications. Calculations have been used to represent vapor-liquid-solid equilibria and chemical equilibria for aqueous systems including solubility of gases. Modern simulation methods combined with experiments provide a useful tool for the research and design of new processes as well as evaluating changes in the operational conditions of chemical processes. The Gibbs energy minimization methods ChemSage, and ChemSheet have been used along with activity coefficient models including Pitzer ion interaction model. The calculated results were compared if possible with experiments or with reference data. Further this work consists of studies on oxygen-pressurized peroxide bleaching, which is an important sequence of total chlorine free (TCF) bleaching for environmental reasons. The solution properties like pH have been measured and modelled both in pure H2O2-NaOH-H2O system and in bleaching conditions. Further, the thermodynamic multicomponent model was used with kinetic constraints for pH calculations in reactive solution. The knowledge of the pulp- and solution properties along with the results of the model calculations could be used for optimisation of the bleaching process with respect to reaction time and temperature. Thermodynamics provides a practical tool for the estimation of the chemical states of pulp and paper solutions as well as in hydrometallurgical applications. Such a fundamental approach relates to the chemical energy, chemical reactions, solubility of gases and salts, and an important online process parameter pH. The Gibbs energy approach was further applied to equilibrium and reaction dynamic studies of multiphase CO2-CaCO3-H2O system.

This thesis consists of an overview and of the following 5 publications:

  1. Salminen J., Koukkari P., Jäkärä J. and Paren A., 2000. Thermochemical experiments and modelling of the PO bleaching stage. Journal of Pulp and Paper Science 26, number 12, pages 441-447.
  2. Kaskiala T. and Salminen J., 2003. Oxygen solubility in industrial process development. Industrial & Engineering Chemistry Research 42, number 8, pages 1827-1831.
  3. Salminen J. and Antson O., 2002. Physicochemical modeling of a bleaching solution and reaction. Industrial & Engineering Chemistry Research 41, number 13, pages 3312-3316.
  4. Koukkari P., Pajarre R., Pakarinen H. and Salminen J., 2001. Practical multiphase models for aqueous process solutions. Industrial & Engineering Chemistry Research 40, number 22, pages 5014-5020.
  5. Salminen J., Kobylin P., Chiavone-Filho O. and Liukkonen S., 2004. Gibbs energy approach for aqueous processes with HF, HNO3 and CO2-CaCO3. AIChE Journal 50, number 6, accepted for publication.

Keywords: Gibbs energy, modelling, aqueous, electrolyte, process

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© 2004 Helsinki University of Technology

Last update 2011-05-26