Impacts of diffusive transport on carbonate mineral formation from magnesium silicate-CO2-water reactions

Daniel E. Giammar, Fei Wang, Bin Guo, J. Andrew Surface, Catherine Anne Peters, Mark S. Conradi, Sophia E. Hayes

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Reactions of CO2 with magnesium silicate minerals to precipitate magnesium carbonates can result in stable carbon sequestration. This process can be employed in ex situ reactors or during geologic carbon sequestration in magnesium-rich formations. The reaction of aqueous CO2 with the magnesium silicate mineral forsterite was studied in systems with transport controlled by diffusion. The approach integrated bench-scale experiments, an in situ spectroscopic technique, and reactive transport modeling. Experiments were performed using a tube packed with forsterite and open at one end to a CO2-rich solution. The location and amounts of carbonate minerals that formed were determined by postexperiment characterization of the solids. Complementing this ex situ characterization, 13C NMR spectroscopy tracked the inorganic carbon transport and speciation in situ. The data were compared with the output of reactive transport simulations that accounted for diffusive transport processes, aqueous speciation, and the forsterite dissolution rate. All three approaches found that the onset of magnesium carbonate precipitation was spatially localized about 1 cm from the opening of the forsterite bed. Magnesite was the dominant reaction product. Geochemical gradients that developed in the diffusion-limited zones led to locally supersaturated conditions at specific locations even while the volume-averaged properties of the system remained undersaturated.

Original languageEnglish (US)
Pages (from-to)14344-14351
Number of pages8
JournalEnvironmental Science and Technology
Volume48
Issue number24
DOIs
StatePublished - Dec 16 2014

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

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