Topological Control on Silicates Dissolution Kinetics

TL;DR

This study links the dissolution rates of silicate solids to their atomic topological constraints, revealing how structural features influence dissolution kinetics through experimental and simulation approaches.

Contribution

It introduces a novel correlation between topological constraints in silicates and their dissolution rates, advancing understanding of structural control on dissolution kinetics.

Findings

Dissolution rates vary over four orders of magnitude.

Number of topological constraints predicts activation energy barriers.

Structural constraints hinder local network reorganization during dissolution.

Abstract

Like many others, silicate solids dissolve when placed in contact with water. In a given aqueous environment, the dissolution rate depends highly on the composition and the structure of the solid, and can span several orders of magnitude. Although the kinetics of dissolution depends on the complexities of both the dissolving solid and the solvent, a clear understanding of which critical structural descriptors of the solid control its dissolution rate is lacking. Through pioneering dissolution experiments and atomistic simulations, we correlate the dissolution rates - ranging over four orders of magnitude - of a selection of silicate glasses and crystals, to the number of chemical topological constraints acting between the atoms of the dissolving solid. The number of such constraints serves as an indicator of the effective activation energy, which arises from steric effects, and prevents the network from reorganizing locally to accommodate intermediate units forming over the course of the dissolution.