Interface Induced Carbonate Mineralization: A Fundamental Geochemical Process Relevant to Carbon Sequestration [report]

H. Henry Teng, Huifang Xu
2013 unpublished
FINAL REPORT Background Vast majority of literature work concludes that the strong Mg 2+ hydration is the ultimate blockage to low-T anhydrous Mg-CO 3 crystallization and the incorporation of Mg 2+ in carbonate (i.e. the dolomite problem). A direct manifestation of the strong Mg-H 2 O association can be found in the products of low-T Mg-CO 3 precipitation which yields exclusively hydrated phases (barringtonite MgCO 3 ·2H 2 O, nesquehonite MgCO 3 ·3H 2 O, lansfordite MgCO 3 ·5H 2 O;
more » ... H 2 O; hydromagnesite Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O, dypingite Mg 5 (CO 3 ) 4 (OH) 2 ·5H 2 O, and artinite Mg 2 (CO 3 )(OH) 2 ·3H 2 O) depending on experimental conditions 1 . However, a closer look at these minerals indicates that rarely any obvious and predictive trend can be deduced concerning their water content. For example, it is widely known that tri-hydrated nesquehonite is the most commonly formed at ambient condition and magnesite only occurs at T > 60 -100 o C 2,3,4 . If higher T favors the dehydration as shown by the shift from tri-hydrate to anhydrate at increasing temperature, we would expected to see di-hydrate (barringtonite) or even mono-hydrate en route. Yet it was reported that higher T (> ~ 40 o C) only brings up various basic forms 5, 6, 7, 8 . Furthermore, if octahedron is the dominant geometry of Mg 2+ hydration shell
doi:10.2172/1089154 fatcat:wdexj25l6rdvbogdqfyfazwicu