Pitzer ion-interaction parameters for Al(III) in the {H + Na + K + Ca + Mg + Cl + H2O} system up to salts solubility at 298.15 K

Abstract : The fundamental research and economic interest of industrials for natural brines is continuously increasing all over the World. More and more substances are extracted from these brines, needing the development of specific exploitation processes. Geochemical modeling can help these industrial technologies providing robust geochemical codes and relevant databases for describing and predicting the critical chemical reactions/steps inside these specific and complex media (dissolution/ precipitation of salts, corrosion/scaling problems…). The Pitzer approach is usually quoted to describe such complex systems but its related databases need to be continuously improved to integrate new chemical species and interaction parameters of complex aqueous systems. This study focuses on very acidic systems and on the efforts made to define the interactions of Al(III) species inside the H-Na-K-Mg-Ca-Cl-H2O system at 25°C. The Pitzer interaction parameters determined in this study allow the description of the thermodynamic behavior of ternary systems up to salt solubility. These parameters are implemented in a database adapted to the geochemical code PHREEQC.