A general, microkinetic model for dissolution of simple silicate and aluminosilicate minerals and glasses as a function of pH and temperature

Silicates and aluminosilicates form 95 % of Earth surface rocks and contribute substantially to building materials. Understanding their dissolution is essential for understanding the impact of mineral-H₂O-CO₂ equilibria and rock weathering on the carbon cycle and for optimising material performance and safety. Predicting dissolution rates is a key but traditional empirical models rely on non-integer reaction orders, which have little meaning, mechanistically and often must be determined for each system separately.

We present a microkinetic model for silicate dissolution, that describes behaviour of crystalline and amorphous silicates, with and without aluminium. The model, which builds on transition state theory for surface group hydrolysis, offers a general framework, that is applicable across a range of silicate materials. It considers factors, such as surface deprotonation and electrostatic interactions. The model predictions show excellent agreement with observed activation energies and dissolution rates, over a broad pH range, demonstrating the importance of electrostatic surface interactions and the role of aluminium in enhancing dissolution, particularly at low pH. The model predicts dissolution at high temperature and salinity so is robust for application in a variety of environmental scenarios. The advanced understanding of silicate dissolution offers promise for optimising material design, climate modelling and geochemical applications.