MYCOLab Ai Logo - gold and army green

The effect of calcium on the removal of Cd2+ in the formation of biogenic secondary iron minerals

Summary

Acid mine drainage from mining operations contains toxic cadmium that pollutes water supplies. This research shows that naturally occurring bacteria (Acidithiobacillus ferrooxidans) can help remove cadmium by forming iron minerals. Adding calcium and potassium ions together significantly improves this process, with cadmium being trapped in mineral precipitates rather than just adsorbed to surfaces. This biological approach offers a practical and sustainable method for treating contaminated mining water.

Background

Acid mine drainage (AMD) is a major environmental problem containing high concentrations of heavy metals like cadmium. Secondary iron minerals formed through bacterial oxidation can effectively remove heavy metals from contaminated water. The role of calcium ions in this process requires further investigation, particularly in sulfate-rich environments.

Objective

This study investigates the effect of calcium ions (Ca2+) on cadmium (Cd2+) removal during the formation of biogenic secondary iron minerals mediated by Acidithiobacillus ferrooxidans. The research examines how Ca2+ and iron/potassium molar ratios affect pH, Fe2+ oxidation efficiency, mineral formation, and Cd2+ removal efficiency.

Results

Cd2+ removal efficiency was highest in the Fe/K=3 with Ca2+-30 mg/L treatment (52.88%), followed by Fe/K=3 (45.76%), Blank (23.46%), and Ca2+-30 mg/L alone (18.42%). Co-precipitation was the dominant removal mechanism, accounting for 5.63 to 14.83 times more Cd2+ removal than adsorption. The combined action of K+ and Ca2+ resulted in the strongest biological oxidation and mineral formation.

Conclusion

The quantity and type of secondary iron minerals directly affect Cd2+ removal efficiency. Controlling the Fe/K molar ratio to 3 significantly increases mineral production and Cd2+ removal. The synergistic effect of K+ and Ca2+ enhances bacterial oxidation ability and promotes co-precipitation as the primary mechanism for heavy metal removal. This approach provides a practical solution for treating heavy metals in acid mine drainage.
  • Published in:Scientific Reports,
  • Study Type:Experimental Study,
  • Source: 10.1038/s41598-024-72764-7, PMID: 39277706
Scroll to Top