One of the challenges in ensuring the safe and permanent storage of acid gases such as CO2 and H2S via conversion to calcium or magnesium carbonates or sulfides is a limited understanding of the kinetics of dissolution of the Ca- and Mg-bearing feedstocks which is considered as the rate-limiting step. A lack of comprehensive mechanistic understanding of the dissolution behaviors of naturally occurring Ca- and Mg-bearing minerals in conjunction with laboratory- and field-scale measurements limits our ability to accurately predict the fate of acid gases post-injection in the subsurface environment. With increasing global interest in engineering subsurface gas storage technologies (e.g., CO2 storage in basalt in Iceland and Washington State in the US, and in Oman peridotite), there is a need to develop a multi-scale understanding of CO2 interactions that range from the atomic- to the field-scale. In this study, we probe the dissolution behaviors of anorthite (CaAl2Si2O8), a major constituent of basalt using in-operando synchrotron X-ray reflectivity measurements. This approach allows us to determine the formation of amorphous aluminosilicate layer during the dissolution of anorthite in varying pH environments. By combining this approach with laboratory-scale measurements, we can determine the onset of relatively fast surface dissolution vs. slower mass transfer limited dissolution behaviors. This approach allows us to develop a comprehensive understanding of the chemo-morphological coupling that influences reactive gas-liquid-solid interactions in the subsurface environment.

Probing the surface dissolution behavior of anorthite using in-operando X-ray reflectivity measurements for accelerated acid gas storage

255th National Meeting (2018)

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