Two-phase water: structural evolution during freezing - thawing according to optical microscopy

TL;DR

This study investigates the structural evolution of water during freezing and thawing, focusing on the behavior of free and bound water phases and their impact on physical properties and natural phenomena like snowballs.

Contribution

It provides detailed optical microscopy observations of two-phase water dynamics during freezing and thawing, revealing microstructural changes and bubble formation processes.

Findings

Bound water remains visible as dispersed phase during freezing.

Air bubbles are released during freezing and form channels during melting.

Physical properties of melt water change due to microdispersed phase loss.

Abstract

The structural dynamics of ice in the freezing - thawing process has been studied in the context of the concept of two-phase water. It was previously shown that water is a two-phase system consisting of free and bound (liquid crystal) fractions. Bound water is represented by hydrated shells of sodium chloride microcrystals, which are constantly present in water and are visible in the optical microscope as a dispersed phase. With rapid freezing, free water crystallizes, turning into ice with the inclusion of the dispersed phase. At this stage, xenogenic air bubbles are released. When ice melts, multiple small bubbles form from diffusely dissolved air. At the same time, the ice acquires a characteristic cellular structure. Bubbles grow, merge and form variegated air channels that contribute to the release of air into the melt water. The dispersed phase during the freezing of water under the conditions of our experiment did not show external signs of glaciation. However, when ice melted, a part of this fraction was kneaded from the main volume of water in the form of loose flakes. The loss of water of part of the microdispersed phase and most of the gases causes a change in a number of physical properties of the melt water. Possible involvement of the observed processes in the appearance of "snowballs" on the banks of rivers is discussed.