Comparative Thermodynamic Theoretical Modeling of Brines From Chott Djerid, Southeastern Tunisia and Sebkha Bazer, Northeast Algeria

Introduction

Saline systems are widely distributed in the world. Several studies have treated mineral/solution interactions as well as the geochemical evolution of salts and brines in the lakes, chotts, and sebkhas ecosystems (Geuddari et al., 1984; Rettig et al., 1980; Jones & Deocamp, 2003; Hacini et al., 2008). The thermodynamic calculations based on the Pitzer (1973) equations are often used to analyze the geochemical evolution of saline lake waters during evaporation. Harvie & Weare (1980) and Eugster et al., (1980) adopted these equations for the evaporation of natural brines in closed systems, and they were successfully applied to the interpretation of a number of evaporites systems (Eugster & Maglione, 1979; Gac et al., 1979; Gueddari et al., 1984). The initial brine composition and the equilibrium constants of evaporite minerals entirely control the chemical evolution of evaporative systems in closed basins. For brine systems, thermodynamic models are typically used to describe phase equilibrium. The exploitation of brine resources can be governed by the phase equilibrium of saltwater systems (Pengsheng, 2016; Mianping et al., 2016). The crystallization sequence during evaporation of natural brine at the Chott Djerid and Sebkha Bazer concentration ponds reflected the findings of both Hardie and Eugster's evolutionary model and the PHREEQC simulated model. The evaporation simulation was performed using the phase diagram and Pitzer's model for the quaternary system. The main goal of this chapter is to develop a functional model of reactivity for the analysis of complex systems and to provide a better understanding of the crystallization sequence during the evaporation process, especially the water-mineral chemical interaction, using geochemical speciation modeling software. Consequently, the calculation of the activity coefficients of various species is therefore very important. In fact, the Pitzer model was chosen because it had already been successfully applied to complex salt systems (Lach, 2015; Essefi et al., 2020; Essefi et al., 2021a,b).