Conference article

The coupling behaviors of mass transfer of aqueous CO₂ with mineral reactions of aqueous CO₂ with rock anorthite are investigated by chemical potential gradient and concentration gradient models; respectively. SAFT1-RPM is used to calculate the fugacity of CO2 in brine. The effective diffusion coefficients of CO₂ are obtained based on the experimental kinetic data reported in literature. The calculation results by the two models and for two cases (mass transfer only and coupling mass transfer with mineral reaction) are compared. The results show that there are considerable discrepancies for the concentration distribution with distance by the concentration gradient and chemical potential gradient models; which implies the importance of consideration of the non-ideality. And the concentrations of aqueous CO₂ at different distances by the concentration gradient model are higher and further than that by the chemical potential gradient model. The mineral reaction plays a considerable role for the CO₂ geological sequestration when the time scale reaches 10 years for the anorthite case.

CO₂ geological sequestration; Non-equilibrium thermodynamics; Chemical potential gradient; Mass transfer; Geochemical reaction