Immobilization of mercury using high-phosphate culture-modified microalgae

Area of Science:

• Environmental Science
• Biotechnology
• Materials Science

Background:

• Mercury (Hg(II)) contamination poses significant environmental and health risks.
• Phosphate enrichment in water bodies leads to eutrophication.
• Effective methods for simultaneous removal and immobilization of heavy metals and nutrients are needed.

Purpose of the Study:

• To develop a novel strategy for Hg(II) immobilization using algal biomass.
• To enhance Hg(II) removal by surface modification of algal cells with phosphate.
• To stabilize Hg(II)-loaded biomass through charring to prevent leaching.

Main Methods:

• Algal cells (Scenedesmus obtusus XJ-15) were incubated in high-phosphate cultures for surface modification.
• Phosphate-rich biomass was used as an adsorbent for Hg(II) removal.
• Hg(II)-loaded biomass was charred at different temperatures for stabilization.

Main Results:

• The highest concentration of surface phosphoryl functional groups was achieved in 80 mg/L P cultures.
• Phosphate-modified biomass (B-80) exhibited a maximum Hg(II) sorption capacity of 95 mg/g at pH 5.0.
• Charring at 300°C resulted in the lowest Hg(II) leaching rate without phosphate release.

Conclusions:

• The developed strategy effectively removes Hg(II) and phosphate from water.
• Surface phosphoryl functional groups are crucial for enhanced Hg(II) sorption and immobilization.
• The charring process successfully immobilizes Hg(II) and prevents phosphate leaching, offering a promising solution for water remediation.