Boron incorporation into precipitated calcium carbonates affected by aqueous pH and boron concentration
Journal
Journal of Hazardous Materials
Journal Volume
383
Journal Volume
383
Start Page
121183
ISSN
03043894
Date Issued
2020-02-05
Author(s)
Abstract
The objectives of this study were to investigate the amount of B incorporation into precipitated calcium carbonate (PCC) in the coprecipitation process, and to determine specific mineral phases (calcite or vaterite) and the mode of B coordination (trigonal or tetrahedral) in PCC under different pH and B concentrations. The amount of B incorporation into PCC increased in general with increasing aqueous B (Baq) concentrations in the pH range from 8 to 12. The B removal by PCC reached maximum (∼200 mmol kg−1) at pH 10 with Baq concentrations between 30 and 50 mM. The transformation of vaterite to calcite was promoted with increasing Baq at pH 8 and 10, whereas an excess concentration of aqueous (poly)borate anions (100 mM) inhibited crystal growth of calcite. As determined by B K-edge X-ray absorption fine structure spectroscopy, the coordination of B incorporated in PCC was preferentially tetrahedral (IVB, 55–70%) over trigonal (IIIB, 30–45%) at Baq <75 mM. In contrast, the preferential incorporation of IVB into PCC was not observed in the solution with a high B concentration (i.e., 100 mM). The amount of B incorporation, the morphology of PCC and B coordination in PCC were remarkably changed in high Baq concentrations.
Subjects
Borate
Boric acid
Coprecipitation
Polyborate
X-ray absorption spectroscopy
Publisher
Elsevier B.V.
Type
journal article