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Dispersion of Small Ceramic Particles (Al(2)O(3)) with Azotobacter vinelandii
T Ren1, N B Pellerin, G L Graff
1Departments of Microbiology and Materials Science and Engineering and Advanced Materials Technology Center, University of Washington, Seattle, Washington 98195.
Applied and Environmental Microbiology
|September 1, 1992
Summary
Bacterial alginate effectively disperses alumina particles in aqueous suspensions. This discovery enables enhanced ceramic processing through an in situ bacterial coating method, improving particle packing and reducing viscosity.
Area of Science:
- Materials Science
- Biotechnology
- Ceramic Engineering
Background:
- Small ceramic particles, like alumina, exhibit high surface charges hindering uniform dispersion in aqueous suspensions and dense compact formation.
- Effective dispersion is crucial for advanced ceramic applications requiring high packing densities and controlled rheology.
Purpose of the Study:
- To investigate the dispersion properties of alumina particles coated with alginate from Azotobacter vinelandii.
- To explore the potential of an in situ bacterial process for alginate coating of ceramic particles.
- To evaluate the impact of alginate coating on suspension viscosity and particle packing density.
Main Methods:
- Alumina particles were treated with bacterial alginate, and adsorption was quantified.
- Azotobacter vinelandii's growth and alginate production in the presence of alumina particles were assessed.
- In situ processing experiments were conducted to measure particle-packing densities and suspension viscosities.
Main Results:
- Alginate treatment resulted in well-dispersed alumina particle suspensions.
- Bacterial alginate strongly adhered to the alumina surface, with significant adsorption observed.
- Azotobacter vinelandii demonstrated robust growth and alginate production even with high alumina concentrations.
- In situ processing led to significantly increased particle-packing densities and substantial reductions in suspension viscosity (4- and 60-fold for 5% and 10% suspensions, respectively).
- Bacteria were easily removed from the coated alumina particles post-processing.
Conclusions:
- Bacterial alginate is a highly effective agent for improving the dispersion of alumina particles in aqueous media.
- An in situ process utilizing Azotobacter vinelandii offers a viable method for coating ceramic particles with alginate.
- This approach significantly enhances ceramic processing by improving particle packing and reducing suspension viscosity, with straightforward bacterial removal.