Understanding the alkali fusion activation mechanism of quartz treated by sodium hydroxide at atomic level

Abstract

The alkali fusion of quartz by NaOH at atomic level was studied using reactive force field molecular dynamic (ReaxFF MD) simulations. It was found that NaOH activates quartz through two ways: one is that the OH^- ions interact with the hydroxyl groups on quartz surface to form water molecules and ionic bonds, the other one is that the violently moving Na⁺ ions break the Si-O bonds both on the surface and inside of the quartz. Due to the confinement effect, Si atoms can only vibrate in a narrow region. However, the breakage of the Si-O bond results in an increase in the number of Q3, the appearance of Q2, Q1, Q0, and the disruption of the quartz network structure. The above findings provide a deep insight into the alkali fusion of quartz, and demonstrate that to active the quartz surface using low-alkali dosage is theoretically feasible.