(90c) Modeling Aqueous Lithium Salt Systems with Association Electrolyte Nonrandom Two-Liquid Activity Coefficient Model

The advancement of process design, development, and simulation of electrolyte systems fundamentally lies within rigorous thermodynamic modeling. With high surface charge density, lithium ion exhibits strong hydration strength and results in exceedingly high solution non-ideality in aqueous lithium salt solutions. In this work, the recently developed association electrolyte nonrandom two-liquid (AeNRTL) model¹ is used to establish a comprehensive thermodynamic model for aqueous solutions of LiCl, LiBr, LiI, LiNO₃, and their mixed-salt systems. The solution non-ideality of the system due to ion hydration and ion-pairing is accounted for with the ion-specific association strength parameters while the solution non-ideality due to van der Waals physical interactions is captured with the binary water-salt and salt-salt interaction parameters. With the association strength parameters and the binary interaction parameters regressed from experimental data, we show the AeNRTL model provides the first-ever accurate engineering correlation for the available thermodynamic property and solubility data of aqueous lithium salt solutions over salt concentrations up to saturation and temperatures up to 523.15 K.

¹ Y. Lin, C.-J. Hsieh, C.-C. Chen, “Association-based Activity Coefficient Model for Electrolyte Solutions,” AIChE Journal, 2021, e17422. Article DOI: 10.1002/aic.17422