Creating an atomistic model of the quartz-water interface is a useful starting point in the effort to understand silicate dissolution. Numerous experiments have been performed that measure the rate of silica dissolution as a function of pH, ionic strength, salt type and temperature. These experiments observe orders of magnitude changes in dissolution rate without a significant change in activation energy. Consequently, a number of investigators have suggested that changes in the structure of the quartz-water interface are responsible for increasing dissolution rates while the energy barrier to hydrolysis of Si-O-Si linkages does not vary dramatically. This work uses planewave density functional theory (DFT) and classical force field calculations to examine changes in the structure and dynamics of the quartz (101)-water interface as a function of pH, salt type and temperature. The predicted changes in interfacial structure observed in the simulations are discussed in terms of their implications for changes in the dissolution rate of quartz and observations of non-linear optical signals.

DFT-MD simulations of the quartz (101)-water interface as a function of pH, ionic strength, salt type and temperature: Implications for dissolution mechanisms

249th National Meeting (2015)

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