Abstract
Microbial-induced calcium carbonate precipitation (MICP) is a biological process inducing biomineralization of CaCO3. This can be used to form a solid, concrete-like material. To be able to use MICP successfully for producing solid materials, it is important to understand the formation process of the material in detail. It is well known, that crystallization surfaces can influence the precipitation process. Therefore, we present in this contribution a systematic study investigating the influence of calcite seeds on the MICP processes. We focus on the pH changes during the crystallization process measured with absorption spectroscopy and on the optical density (OD) signal to analyze the precipitation process. Furthermore, optical microscopy was used to visualize the precipitation processes in the sample and connect them to changes in pH and OD. We show that there is a significant difference in the pH evolution between samples with and without calcite seeds present and that the shape of the pH evolution and the changes in OD can give detailed information about the mineral precipitation and transformations. In the presented experiments we show that amorphous calcium carbonate (ACC) can also precipitate in the presence of initial calcite seeds, which can have consequences for consolidated MICP materials.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
† Electronic Supplementary Information (ESI) available: The supporting information includes Table S1 showing the dilution table of bacterial cultures and Table S2 showing the initial pH values of seeded and unseeded samples. Furthermore, Figure S1 shows SEM images of the initial calcite seeds and Figure S2 confocal laser scanning microscope images of fluorescent calcite seeds]. See DOI: 00.0000/00000000.