wAbstract
@Basaltic glass dissolution rates were measured in mixed-flow
reactors at basic pH and at 25 and 70 in aqueous solutions supersaturated
with respect to calcite for up to 140 days. Inlet solutions were
comprised of NaHCO3}CaCl2
with ionic strengths 0.03 mol kg-1. Scanning Electron
Microscope images show that significant CaCO3
precipitated during these experiments. This precipitate grew on
the basaltic glass in experiments performed in Ca-free inlet solutions,
but nucleated and grew independently of the glass surfaces in
experiments performed in Ca-bearing inlet solutions. In those
experiments where CaCO3 precipitated on the
glass surface, it grew as discrete crystals; no pervasive CaCO3 layers were observed. The lack of structural
match between glass and calcium carbonate favors CaCO3
nucleation and growth as discrete crystals. Measured basaltic
glass dissolution rates based on either Si, Al, or Mg were both
1) independent of time during the experiments, and 2) equal to
that of corresponding control experiments performed in NaHCO3-free inlet solutions. Taken together, these
observations show that basaltic glass dissolution rates are unaffected
by the precipitation of secondary CaCO3 precipitation.
It seems therefore likely that carbonate precipitation will not
slow basaltic glass dissolution during mineral sequestration efforts
in basaltic rocks.
Keywords: Glass dissolution rates; CO2 storage;
Carbonate coating; Carbonatization; Mineral-carbon sequestration;
Mixed-flow reactorsx
1. Introduction
2. Theoretical background
3. Materials and methods
4. Experimental results
@4.1. Basaltic glass dissolution in aqueous carbonate inlet
fluids at 70 (experimental series 1 and 2)
@4.2. Basaltic glass dissolution in carbonate-rich fluids at 25
(experimental series 8 and 9)
@4.3. Basaltic glass dissolution in calcium-bearing aqueous carbonate
fluids at 25 (experimental series 4 and 6)
@4.4. Comparison with previously published basaltic glass dissolution
rates
5. Discussion
6. Conclusions
Acknowledgments
References