dynamics of non-dense sodium silicate - water system studied by molecular dynamics

[Display omitted] •Dynamics in non-dense sodium silicate – water systems.•Role of temperature and water content.•Kinetics from Molecular Dynamics Simulations. A wide range of applications of amorphous silica makes this mineral an object of various investigations conducted by the scientists and the industry. The procedure of its precipitation is well studied, and we dispose of a range of models describing the succeeding processes. However, the size restrictions of experimental methods limit the knowledge about the very first instants of the process. Therefore, to contribute to filling this gap, our study aimed at elucidating some aspects of silica oligomerization. To access the molecular details of the process, we applied the Molecular Dynamics method with the ReaxFF Reactive Forcefield. We studied sodium silicate solutions with high initial concentration. We took up the topic of the effect of temperature, the size of the simulated system, and the amount of water in the simulations. Our considerations led us to conclusions about the reaction mechanism. We applied this knowledge to propose later a simple model describing the evolution of small species. Finally, we estimated the corresponding kinetic constants, which explained well the succession of events and reasonably agreed with the theory.