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| Titel |
Effects of ferrous iron on the precipitation and growth of CaCO3 in slightly
basic aqueous solutions, from macro to nanoscale |
| VerfasserIn |
Fulvio Di Lorenzo, Alejandro Burgos-Cara, Encarnacion Ruiz-Agudo, Christine V. Putnis, Manuel Prieto |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130527
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| Publikation (Nr.) |
 EGU/EGU2016-10796.pdf |
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| Zusammenfassung |
| The precipitation of CaCO3 and further growth of calcite has been studied in aqueous
solutions containing ferrous iron (Fe2+). Two different types of bulk experiments have been
carried out. Nucleation experiments have been conducted at pH 9 with five different
CaTOT/FeTOT ratios: 10, 5, 2.5, 1.25 and 0.625. As well, calcite growth experiments have
been conducted at pH 8.5 (following the constant composition method) with CaTOT/FeTOT
ratios: 100, 50 and 25; this higher dilution partially reduces the impact of inhibition on
growth of calcite occurring when CaTOT/FeTOT ≤ 25. Parameters such as the solution pH,
[Ca2+], conductivity, solution transmittance (610 nm), and volume added were continuously
monitored by a Titrino 905 system (Metrohm, Switzerland). After the experiments, the
CaCO3 precipitates were collected, filtered, dried and characterized by powder-XRD,
HRTEM, FESEM-EDX, EMPA. Solution composition was determined by ICP-MS.
Additionally, in-situ Atomic Force Microscopy (AFM) flow-through growth experiments
were conducted in a sealed fluid cell using freshly cleaved natural calcite (Iceland spar).
The solution composition in AFM experiments was analogous to the bulk growth
experiments. The results of these experiments reveal the significant influence of
ferrous iron on nucleation and growth in the CaCO3-H2O system, reflected as well in
polymorphic selection in this system.Finally, thermodynamic considerations for the
system Ca-Fe-CO2-H2O are discussed that allow the modelling of geochemical
processes involving this system, such as geological carbon storage in basaltic rocks. |
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