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Chromate reduction by immobilized palladized sulfate-reducing bacteria
A C Humphries1, I P Mikheenko, L E Macaskie
1School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, United Kingdom.
Biotechnology and Bioengineering
|March 30, 2006
Summary
Researchers developed a palladium bionanocatalyst using bacteria to reduce toxic chromium(VI) to less harmful chromium(III). This novel catalyst shows promise for environmental remediation applications.
Area of Science:
- Environmental Science
- Biotechnology
- Nanocatalysis
Background:
- Hexavalent chromium (Cr(VI)) poses significant environmental and health risks.
- Developing efficient and sustainable methods for Cr(VI) reduction is crucial for remediation.
- Bionanocatalysts offer a promising alternative to traditional chemical catalysts.
Purpose of the Study:
- To synthesize a hybrid palladium bionanocatalyst (Bio-Pd(0)) using resting cells of Desulfovibrio bacteria.
- To evaluate the efficacy of Bio-Pd(0) in reducing Cr(VI) to Cr(III).
- To optimize the performance of immobilized Bio-Pd(0) in a continuous-flow system.
Main Methods:
- Hydrogenase-mediated reduction of Pd(II) to Pd(0) using Desulfovibrio vulgaris and Desulfovibrio desulfuricans.
- Characterization and application of the resulting Bio-Pd(0) catalyst for Cr(VI) reduction.
- Immobilization of Bio-Pd(0) in agar and evaluation in a continuous-flow reactor.
Main Results:
- Bio-Pd(0) effectively reduced Cr(VI) to Cr(III), with similar activity regardless of the bacterial strain used.
- Optimal reduction efficiency was achieved with specific Bio-Pd(0) loading, Cr(VI) concentration, and flow rate in the immobilized system.
- Mathematical modeling accurately predicted catalyst activity, with an apparent K(m) of 430 microM Cr(VI).
Conclusions:
- The developed palladium bionanocatalyst is effective for the reduction of toxic Cr(VI).
- Agar immobilization and continuous-flow operation enhance the catalyst's performance for environmental remediation.
- The Bio-Pd(0) system serves as an 'artificial enzyme' analog with predictable kinetics.