Cyanobacteria as a biosorbent for mercuric ion

Area of Science:

• Environmental Science
• Biotechnology
• Microbiology

Background:

• Mercury (Hg(2+)) contamination poses significant environmental and health risks.
• Biosorption using microorganisms offers a sustainable approach for heavy metal remediation.
• Cyanobacteria are promising candidates for biosorption due to their abundance and resilience.

Purpose of the Study:

• To investigate the biosorption capacity of Spirulina platensis and Aphanothece flocculosa for Hg(2+).
• To determine the influence of key parameters on mercury uptake.
• To evaluate the potential for biomass regeneration and reuse.

Main Methods:

• Batch stirred reaction system used for biosorption experiments.
• Optimization of pH, biomass concentration, and initial metal concentration.
• Analysis of Hg(2+) uptake kinetics and the effect of co-ions (Co(2+), Ni(2+), Fe(3+)).
• Biomass regeneration using HCl and NH(4)Cl over multiple cycles.

Main Results:

• Optimal Hg(2+) uptake achieved at pH 6.0 for both cyanobacteria strains.
• Maximum Hg(2+) loading capacities: 456 mg/g for A. flocculosa and 428 mg/g for S. platensis.
• A. flocculosa removed over 98% of Hg(2+) at 10 ppm initial concentration.
• Biosorption kinetics exhibited a bi-phasic pattern (rapid initial uptake, followed by slower absorption).
• Co(2+), Ni(2+), and Fe(3+) showed synergistic effects on Hg(2+) uptake.
• Successful regeneration of biomass over four sorption-desorption cycles.

Conclusions:

• Spirulina platensis and Aphanothece flocculosa are effective biosorbents for Hg(2+).
• Process parameters significantly influence mercury removal efficiency.
• The synergistic effect of co-ions and biomass regenerability highlight practical application potential.