Can dawsonite permanently trap CO2?

Thermodynamic calculations indicate that although dawsonite (NaAlCO3(OH)2) is favored to form at the high CO2 pressures associated with carbon dioxide injection into sandstone reservoirs, this mineral will become unstable as CO2 pressure decreases following injection. To assess the degree to which dawsonite will persist following its formation in sandstone reservoirs, its dissolution rates have been measured at 80 +/- 3 degrees C as a function of pH from 3 to 10. Measured dawsonite dissolution rates normalized to their BET surface area are found to be nearly independent of pH over the range of 3.5 < pH < 8.6 at 1.58 x 10(-9) mol/(m2 x s). Use of these dissolution rates in reactive transport calculations indicate that dawsonite rapidly dissolves following the decrease of CO2 pressure out of its stability field, leading mainly to the precipitation of secondary kaolinite. This result indicates that dawsonite will provide a permanent mineral storage host only in systems that maintain high CO2 pressures, whereas dawsonite may be an ephemeral phase in dynamic settings and dissolve once high CO2 pressure dissipates either through dispersion or leakage.