Geologic CO2 sequestration (GCS) is one of the most promising methods to mitigate the adverse impact of global climate change. The performance of GCS can be affected by mineral dissolution and precipitation induced by injected CO2. Carboxylic acid ligands are naturally abundant in subsurface environments, and their concentration can be further increased after CO2 injection. Carboxylic acid ligands can strongly affect mineral dissolution and precipitation under various conditions. However, research under conditions relevant to GCS is sparse. This work investigated effects of various carboxylic acid ligands on dissolution of plagioclase at 90oC, 100 atm CO2, and 1 M NaCl, conditions closely relevant to GCS. Mono carboxylic acid ligands (C1-C5) showed no significant effects, while oxalate, citrate, etc. were found to significantly enhance plagioclase dissolution. In addition, this work investigated the effects of 0.05 M sulfate on plagioclase (anorthite) dissolution. The adsorption of sulfate on anorthite was examined using attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy and simulated using density functional theory (DFT) calculations. The dissolution rate of anorthite was enhanced by a factor of 1.36 by the formation of inner-sphere monodentate complexes between sulfate and the aluminum sites on anorthite surfaces. However, this effect was almost completely suppressed in the presence of 0.01 M oxalate. The results provide new insights into the effects of carboxylic acid ligands on plagioclase dissolution during GCS.

Effects of carboxylic acid ligands on plagioclase dissolution under conditions relevant to geologic sequestration

249th National Meeting (2015)

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