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Oxygen diffusivity in calcium alginate gel beads containing Gluconobacter suboxydans
U Mehmetoglu1, S Ates, R Berber
1Dept. of Chem. Eng., Faculty of Sciences, Ankara University, Turkey.
Summary
This study determined oxygen diffusion in immobilized systems using the Moment Analysis Method. Smaller gel beads significantly enhance bioreactor production efficiency.
Area of Science:
- Biochemical Engineering
- Mass Transfer Phenomena
- Biotechnology
Background:
- Immobilized enzyme and microorganism systems are crucial for industrial production and analysis.
- Understanding mass transfer is key to optimizing these systems.
Purpose of the Study:
- To determine the effective diffusion coefficient of oxygen in calcium alginate gel.
- To investigate the influence of gel and cell concentration on oxygen diffusion.
- To evaluate mass transfer resistance and effectiveness factors in bioreactors.
Main Methods:
- Utilized the Moment Analysis Method for the first time to measure oxygen diffusion coefficients.
- Experimentally determined effective diffusion coefficients (De) in calcium alginate gels with varying concentrations of gel and immobilized Gluconobacter suboxydans.
- Calculated liquid-particle mass transfer coefficients and effectiveness factors.
Main Results:
- Oxygen diffusion coefficient showed minimal dependence on gel concentration (1-3%).
- Effective diffusion coefficient decreased with increasing immobilized Gluconobacter suboxydans concentration (0-6%).
- External mass transfer resistance was found to be negligible.
- Effectiveness factors were 0.39 and 0.21 for gel beads of 0.1 cm and 0.2 cm radius, respectively.
Conclusions:
- Smaller gel bead size (0.1 cm vs 0.2 cm) substantially improves bioreactor production efficiency.
- Optimizing gel bead size is critical for enhancing performance in immobilized cell bioreactors.