Albite feldspar dissolution kinetics as a function of the Gibbs free energy at high pCO2

Abstract

We are currently measuring the dissolution kinetics of albite feldspar at 100 °C in the presence of high levels of dissolved CO2 (pCO2 = 9 MPa) as a function of the saturation state of the feldspar (Gibbs free energy of reaction, ∃G). The experiments are conducted using a flow through reactor, thereby allowing the dissolution reactions to occur at a fixed pH and at constant, but variable saturation states. Preliminary results indicate that at far-from-equilibrium conditions, the dissolution kinetics of albite are defined by a rate plateau, with R ≈ 5.0 x 10-10 mol m-2 s-1 at -70 -40 kJ mol-1, the rates decrease sharply, revealing a strong inverse relation between the dissolution rate and free energy. Based on the experiments carried out to date, the dissolution rate-free energy data correspond to a highly non-linear and sigmoidal relation, in accord with recent studies.