wAbstract
@Far-from-equilibrium dissolution experiments with diopside and
basaltic glass in mixed-flow reactors at 70Ž and pH 8.2 show that
solute concentrations do not reach steady state over the experimental
duration of 45-60 days. Chemical modelling indicates that during
the dissolution experiments, solutions have become supersaturated
with respect to carbonates in the case of diopside, and carbonates,
clay minerals and zeolites in the case of the basaltic glass.
Decreasing dissolution is therefore interpreted as a result of
secondary surface precipitates blocking the reactive surface area.
Calcite formation was supported in both experiments by a significant
increase in Ca (and Sr) concentrations as pH was abruptly lowered
from 8.2 to 7 because this change increased carbonate solubility
and caused all potential carbonate precipitates to re-dissolve.
The reduction in pH also led to an increase in Si concentration
for diopside and a decrease in Si concentration for basaltic glass.
This observation is in accordance with previous experiments on
the pH-dependent dissolution rates of pyroxenes and basaltic glass.
Keywords: dissolution; diopside; basaltic glass; carbonate coating;
carbon dioxide sequestration; mixed-flow reactor.x
Introduction
Method and materials
Results and discussion
Conclusion
Acknowledgements
References