Program > Browse abstracts by speaker > Gion Austin

The reaction between silicate glasses and aqueous fluids is topic of interest for a variety of fields including the earth, materials, nuclear, and archeological sciences. Developing an understanding of the corrosion of both natural and synthetic silicate glasses; therefore, has widespread impacts on elucidating processes ranging from metasomatic reactions in geological systems to the storage of nuclear waste to conservation and age dating of glass artifacts. To this end, we have performed dissolution experiments at 150°C on a peralkaline rhyolite from the Aluto volcano (Ethiopian rift) with an alkaline solution with a pH of 12.87. Experiments were performed in both static Parr reactors at the University of Oxford and a flow-through apparatus at GNS, New Zealand for durations of hours to weeks. We find that the primary alteration mineral is the zeolite chabazite along with quartz and potassium feldspar. Additionally, the interaction of the glass with the alkaline solution produces a leach layer at the glass-fluid interface. This leach layer, and alteration products, retain elements such as Al, Ca, Mn, Rb, Sr, Th, and U, whereas elements that are liberated from the glass include Li and K, as well as Si due to the elevated pH. The surface area normalized dissolution rate of the glass as calculated from the release of silicon into the fluid is 10-8.4 to 10-6.5 mol m-2 s-1. This dissolution rate is faster than previously reported rates at equivalent temperatures and pH's by up to ~1 order of magnitude. These preliminary results highlight that glass dissolution requires consideration of glass composition beyond the simple breaking of network forming bonds and dissolution of silicon into the fluid. Additional work is being carried out present at variable acid and alkaline conditions in order to better constrain corrosion of natural and synthetic glasses.