Publication Date:
2015-04-13
Description:
The effects of pH and phosphate on the
precipitation of calcium carbonate polymorphs from aqueous
solution were investigated. Experiments were carried out at
near-freezing temperature and two different pH conditions (pH
13.4 and 9.0). At each pH condition, solutions having different
concentrations of CaCl2 and NaHCO3 were mixed to achieve
Ca/CO3 ratios of 1:1 and 10:1 at different pumping rates with
and without phosphate. Results showed that, at pH 13.4, only
ikaite was formed, independent of pumping rate, Ca/CO3 ratio,
and phosphate. At pH 9.0, the precipitate was predominantly
vaterite in the absence of phosphate and ikaite in the presence
of phosphate regardless of the ratio of Ca/CO3. These results
indicate that at low temperatures and moderate alkaline
conditions (pH 9.0), phosphate can act as a switch between ikaite and vaterite polymorphs. Contrastingly, at higher alkaline
conditions (pH 13.4) phosphate is not prerequisite and the high pH in itself is enough to trigger ikaite formation over vaterite.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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