The application of a new “interstitial” model for the Interfacial freezing potential of pure water (Workman-Reynolds Potential) to aqueous solutions

Abstract

A new model of pure water freezing potential (Workman-Reynolds potential), published in Journal of Molecular Liquids 359 (2022) 119278, explained the positive electric charge of ice relative to water during crystallization by the fact that protons were captured faster than hydroxide ions by numerous charge traps in ice - interstitials. In the present article, additions have been made to this model to extend the application of the model from pure water to aqueous solutions with an impurity concentration in the parent solution of 10-4 M or more. The additions take into account the ability of impurity anions and cations to act as acceptors for protons and hydroxide ions in ice. As a result of capture by acceptors, the equilibrium concentrations of protons and hydroxide ions can shift significantly in favor of the former or the latter. This will radically affect the kinetics of filling the charge traps (interstitials) with protons or hydroxide ions and the sign of the electric charge of ice with respect to the solution. In particular, the model explains the negative ice charge during crystallization of 10-4 M KCl solutions.