Thermodynamic modeling of aqueous polyelectrolyte solutions with mixed-valent counterions

Thermodynamic modeling of aqueous polyelectrolyte solutions with salts is of significant interest for many in-dustrial applications. This study applies the polyelectrolyte Nonrandom Two-liquid activity coefficient model to aqueous polyelectrolyte solutions with mixed-valent counterions. A modified Delocalized Binding Theory was proposed to determine the polyion condensation fractions of the mixed counterions. This modified theory ac-counts for the electrostatic binding of the counterions on the polyion, the dissociation entropy of the counterions, and the electrostatic interactions between the uncondensed ionic species. Given the polyion condensation fractions, the critical value of Manning's parameter xi and the amounts of uncondensed polyions and counterions can be calculated along with the activity coefficients of mobile ions. The model successfully correlates experi-mental data for various aqueous polyelectrolyte systems with mixed-valent counterions.

Automated summary

Thermodynamic modeling of aqueous polyelectrolyte solutions with mixed-valent counterions is performed using the polyelectrolyte Nonrandom Two-liquid activity coefficient model. A modified Delocalized Binding Theory is proposed to determine the polyion condensation fractions of the mixed counterions, taking into account the electrostatic binding, dissociation entropy, and electrostatic interactions. The model successfully correlates experimental data for various aqueous polyelectrolyte systems with mixed-valent counterions.