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Calcite precipitation induced by polyurethane-immobilized Bacillus pasteurii.
S S. Bang1, J K. Galinat, V Ramakrishnan
1Department of Chemistry and Chemical Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA
Enzyme and Microbial Technology
|March 10, 2001
Summary
Bacillus pasteurii immobilized in polyurethane foam efficiently precipitated calcite. This process enhanced concrete strength, suggesting calcite acts as precipitation, not a bonding agent, within the foam matrices.
Area of Science:
- Biomineralization
- Materials Science
- Civil Engineering
Background:
- Polyurethane (PU) foam is a versatile material.
- Bacillus pasteurii is known for its ability to precipitate calcite.
- Immobilization techniques are crucial for industrial applications of microorganisms.
Purpose of the Study:
- To immobilize Bacillus pasteurii in PU foam for calcite precipitation.
- To evaluate the effect of immobilized cells on concrete properties.
- To understand the role of precipitated calcite within the PU matrix.
Main Methods:
- Whole cells of Bacillus pasteurii were immobilized in PU foam.
- Calcite precipitation and ammonia production rates were measured.
- Scanning electron microscopy (SEM) was used to analyze the microstructure.
- Mechanical properties (elastic modulus, tensile strength, compressive strength) of PU and concrete were tested.
Main Results:
- Immobilized Bacillus pasteurii showed high rates of calcite precipitation and ammonia production, comparable to free cells.
- SEM revealed cells embedded within calcite crystals throughout the PU matrices.
- Calcite precipitation in PU minimally affected the polymer's elastic modulus and tensile strength.
- Concrete cubes remediated with PU-immobilized cells demonstrated increased compressive strengths.
Conclusions:
- PU foam effectively immobilizes Bacillus pasteurii for biomineralization.
- The precipitated calcite enhances the mechanical properties of concrete.
- Calcite likely functions as a precipitation product rather than a bonding agent within the PU matrix.