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1

A comparative study of two thermodynamic models applied to solutions of the NH3-H3PO4-H2O and NH3-CO2-NaCl-H2O systems

Jaworski Z., Czernuszewicz M., Gralla Ł.

Chemical and Process Engineering

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2010

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Vol. 31, z. 4

789-811

EN

The required number of parameters and their temperature dependences for two models for the thermodynamic description of electrolyte solutions were analyzed. The Pitzer model and the extended UNIQUAC model were applied to systems used in the fertilizer industry, NH3-H3PO4-H2O, and in the Solvay soda technology, NH3-CO2-NaCl-H2O. Feasibility of the derivation of the activity coefficients was also carried out for those systems. The number of required model equations to be applied along with temperature dependences of the model parameters were presented to explain and compare the complexity of the two models. Experimental data correlations for the model parameters available in the literature were presented and the computing results for the two analysed systems were described. It was also concluded that at the present state of knowledge the activity coefficients can be computed for the solution components of the two systems by the extended UNIQUAC method and for the Pitzer model several simplifications have to be applied.

PL

Zanalizowano liczbę niezbędnych parametrów oraz ich zależności od temperatury dla dwóch modeli do termodynamicznego opisu roztworów elektrolitów. Zastosowano model Pitzera i rozszerzony model UNIQUAC do układów zawierających związki stosowane w przemyśle nawozowym, NH3-H3PO4-H2O, oraz sodowym NH3-CO2-NaCl-H2O. Przeprowadzono ocenę możliwości wyznaczenia współczynników aktywności dla tych układów oraz poziomu złożoności każdego z wymienionych modeli pod względem liczby równań i zależności parametrów modelu od temperatury. Zebrano również dostępne w literaturze wartości parametrów obu modeli i opisano wyniki obliczeń z zastosowaniem tych danych do analizowanych układów. Stwierdzono, że aktualny stan wiedzy umożliwia wyznaczenie współczynników aktywności indywiduów chemicznych wchodzących w skład obu układów rozszerzoną metodą UNIQUAC, a w przypadku modelu Pitzera należy zastosować szereg uproszczeń.

2

Integral enthalpy of solution and Pitzer's parameters for manganese and cobalt sulfates

Przepiera A., Kalbarczyk A.

Polish Journal of Applied Chemistry

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2007

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Vol. 51, nr 1-2

1-10

EN

The integral enthalpy of solution of manganese and cobalt sulfates in water as a solvent, have been measured using isoperibol calorimeter. The enthalpy of solution has been measured as a function of molality. Measurements were carried out at three different temperatures. Enthalpy of solution at infinite dilution was estimated by extrapolation of experimental data. The experimental data have been fitted using the Pitzer's ionic interaction model with an ionic strength dependent second virial coefficient. Pitzcr's model has been also used to calculate osmotic coefficient and activity coefficient. These data can be important in processes, in which one uses solution of transition metal sulfates.

3

Integral enthalpy of solution, osmotic and activity coefficients of transition metal sulfates

Przepiera A., Kalbarczyk A.

Polish Journal of Applied Chemistry

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2006

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Vol. 50, nr 3-4

55-63

EN

The integral enthalpy of solution of transition metal sulfates in water as a solvent, have been measured using isoperibol calorimeter. Measurements were carried out at ambient temperature. The enthalpy of solution has been measured as a function of molality. Enthalpy of solution at infinite dilution was estimated by extrapolation experimental data. These data have been fitted with a Pitzer ion-interaction model with an ionic strength dependent second virial coefficient. Pitzer's model has been also used to calculate osmotic coefficient and activity coefficient. These data fill a gap in the thermodynamic database and make possible planning industrial process, in which one can use transition metal sulfates.