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| Titel |
Kinetics and quantitative modelling of coupled dissolution/precipitation reactions of lead bearing solutions interacting with aragonitic shells. |
| VerfasserIn |
M. Bucca, P. Cubillas, M. Dietzel, S. J. Köhler |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026859
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| Zusammenfassung |
| Elevated lead concentrations in surface and groundwater may cause serious health problems
for aquatic biota and humans. Several processes are known for the removal of lead (Pb) from
the aqueous solutions. In a previous study carried out by Cubillas et al. (2005) cadmium
uptake using aragonite surfaces has been studied. The mechanism involved was a
dissolution-precipitation happening concurrently and demonstrated aragonite’s potential as
metal sorbent. Further studies demonstrated a similar efficiency of aragonite surfaces in
presence of other selected metals as lead (Pb), zinc (Zn) and cobalt (Co) (Köhler et
al., 2007). Before optimizing such a process more a detailed study of the kinetic
effects is necessary. In the present study we focused on the kinetics of the coupled
precipitation/dissolution process for lead removal from polluted soils and waters by
biogenic aragonitic carbonate (CaCO3) shell surfaces according to the following Eq.
1:
CaCO3 + Pb2+ = PbCO3 + Ca2+ . (Eq. 1)
This reaction has been investigated at fixed experimental conditions using synthetic
model systems in batch and single pass flow through and fluidized bed reactors that allowed
quantifying the kinetics of the process of metal carbonate formation. The chemical
parameters pH, alkalinity, temperature, pCO2, and total ion concentration were followed
during several hours. The reaction kinetics was successfully modelled using the geochemical
code PHREEQC (Parkhurst, 1998) using the Plummer-Wigley-Parkhurst equation for both
the dissolution and precipitation process. The precipitated lead bearing solid phases
were characterized mineralogically. Potential applications of this study will be
discussed.
Cubillas, P., Köhler, S. J., Prieto, M., Causserand, C., Oelkers, E.H., 2005. How do
mineral coatings affect dissolution rates? An experimental study of coupled CaCO3
dissolution-CdCO3 precipitation. Geochimica et Cosmochimica Acta 69, Issue 23,
5459-5476.
Köhler, S.J., Cubillas, P., Rodriguez-Blanco, J.D., Bauer, C., Prieto, M., 2007. Removal
of cadmium from wastewaters by aragonite shells and the influence of other divalent cations.
Environmental Science & Technology 41, Issue 1, 112-118.
Parkhurst, D.L., 1998. PHREEQC (Version 2) - A computer program for speciation,
batch-reaction, one-dimensional transport and inverse geochemical calculations. U.S.
Geological Survey Water-Resources Investigations Report, pp 99-4259. |
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