title: Impacts of organic ligands on forsterite reactivity in supercritical CO2 fluids.
abstract: Subsurface injection of CO2 for enhanced hydrocarbon recovery, hydraulic fracturing of unconventional reservoirs, and geologic carbon sequestration produces a complex geochemical setting in which CO2-dominated fluids containing dissolved water and organic compounds interact with rocks and minerals. The details of these reactions are relatively unknown and benefit from additional experimentally derived data. In this study, we utilized an in situ X-ray diffraction technique to examine the carbonation reactions of forsterite (Mg2SiO4) during exposure to supercritical CO2 (scCO2) that had been equilibrated with aqueous solutions of acetate, oxalate, malonate, or citrate at 50 °C and 90 bar. The organics affected the relative abundances of the crystalline reaction products, nesquehonite (MgCO3 · 3H2O) and magnesite (MgCO3), likely due to enhanced dehydration of the Mg(2+) cations by the organic ligands. These results also indicate that the scCO2 solvated and transported the organic ligands to the forsterite surface. This phenomenon has profound implications for mineral transformations and mass transfer in the upper crust.
authors: †Department of Geology and Geophysics, University of Wyoming, 1000 East University Avenue, Laramie, Wyoming 82071, United States.
authors: Quin R S
authors: QR
authors: Miller
authors: †Department of Geology and Geophysics, University of Wyoming, 1000 East University Avenue, Laramie, Wyoming 82071, United States.|‡School of Energy Resources, University of Wyoming, 1000 East University Avenue, Laramie, Wyoming 82071, United States.
authors: John P
authors: JP
authors: Kaszuba
authors: §Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, United States.
authors: Herbert T
authors: HT
authors: Schaef
authors: ∥Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, United States.
authors: Mark E
authors: ME
authors: Bowden
authors: ⊥Energy and Environment Directorate, Pacific Northwest National Laboratory, P.O. Box 999, MS K8-98, Richland, Washington 99352, United States.
authors: Bernard P
authors: BP
authors: McGrail
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D057965:Carbon Sequestration; D002254:Carbonates / Q000138:chemical synthesis*; D008024:Ligands; D008274:Magnesium / Q000032:analysis / Q000737:chemistry; D008903:Minerals / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D002254:Carbonates; D008024:Ligands; D008903:Minerals; D017655:Silicon Compounds; C503823:forsterite; D014867:Water; C005479:magnesium carbonate; D002245:Carbon Dioxide; D008274:Magnesium