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Title: X-ray driven reaction front dynamics at calcite-water interfaces

The interface of minerals with aqueous solutions is central to geochemical reactivity, hosting processes that span multiple spatiotemporal scales. Understanding such processes requires spatially and temporally resolved observations, and experimental controls that precisely manipulate the interfacial thermodynamic state. Using the intense radiation fields of a focused synchrotron X-ray beam, we drove dissolution at the calcite-aqueous interface and simultaneously probed the dynamics of the propagating reaction fronts using surface X-ray microscopy. Evolving surface structures are controlled by the time-dependent solution composition as characterized by a kinetic reaction model. At extreme disequilibria, the onset of reaction front instabilities was observed with velocities of >30 nanometers per second. As a result, these instabilities are identified as a signature of transport-limited dissolution of calcite under extreme disequilibrium.
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Univ. of Illinois, Chicago, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Univ. of Delaware, Newark, DE (United States)
Publication Date:
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Accepted Manuscript
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Additional Journal Information:
Journal Volume: 349; Journal Issue: 6254; Journal ID: ISSN 0036-8075
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
36 MATERIALS SCIENCE; X-ray microscopy; mineral/aqueous interfaces