Mechanistic insights and predictive modeling of ionic strength and temperature effects on Ca(II) adsorption in potassium-enriched brines

The mechanisms and predictive models for the effects of ionic strength and temperature on adsorption capacity remain insufficiently understood. In this work, Ca(II) adsorption removal in potassium-enriched brines from seawater potash production is used as a representative system. From a statistical-physics perspective, higher ionic strength reduced the density of adsorption sites and the number of adsorbates captured per site, and the preferred adsorption orientation changed from perpendicular to parallel, resulting in a lower adsorption capacity and reduced spontaneity. In contrast, higher temperature increased the density of adsorption sites and the number of adsorbates captured per site, and the preferred orientation changed from parallel to perpendicular, yielding a higher adsorption capacity and greater spontaneity. Finally, predictive models of adsorption capacity as functions of ionic strength and temperature were established to support the optimization of related industrial processes.