Synergistic interface behavior of strontium adsorption using mixed microorganisms.

Area of Science:

• Environmental Science
• Microbiology
• Nuclear Chemistry

Background:

• Sustainable nuclear power relies on effective low-level radioactive waste management.
• Microbial remediation of radionuclides requires understanding bacterium-radionuclide interactions.
• Strontium (Sr(II)) is a key radionuclide requiring efficient removal strategies.

Purpose of the Study:

• To investigate the biosorption behavior and mechanisms of Sr(II) using a mixed microbial consortium.
• To determine optimal conditions for Sr(II) biosorption by Saccharomyces cerevisiae and Bacillus subtilis.
• To elucidate the chemical interactions at the interface between Sr(II) and microbial functional groups.

Main Methods:

• Utilized a mixed culture of Saccharomyces cerevisiae and Bacillus subtilis as a biosorbent.
• Optimized the ratio of microorganisms and pH for Sr(II) biosorption.
• Applied kinetic and isotherm models (pseudo-second-order, Langmuir) to describe biosorption.
• Employed spectral and energy spectrum analysis to identify active functional groups.

Main Results:

• The optimal ratio was determined as S. cerevisiae 2.0 g L^-1 to B. subtilis 0.05 g L^-1 at pH 6.3.
• Sr(II) biosorption is a spontaneous and endothermic process.
• Biosorption kinetics followed a pseudo-second-order model, and equilibrium data fitted the Langmuir isotherm.
• Functional groups (hydroxyl, carboxyl, amino, amide) on the microorganisms' surface are primary active sites for Sr(II) binding via chemical complexation.

Conclusions:

• A mixed microbial biosorbent of S. cerevisiae and B. subtilis shows significant potential for Sr(II) remediation.
• Understanding the chemical interactions and optimizing conditions are crucial for effective radionuclide biosorption.
• Microbial functional groups play a vital role in the complexation and removal of strontium from waste streams.