Attachment of Acidithiobacillus ferrooxidans to pyrite in fresh and saline water and fitting to Langmuir and Freundlich isotherms

Objective: This study aims to investigate the attachment of Acidithiobacillus ferrooxidans to pyrite in two different environments: fresh and saline water (water with 35 g/L of NaCl or 0.6 M). Adsorption isotherms were analyzed using the Langmuir and Freundlich models. Saline water is water with 35 g/L of NaCl (0.6 M), which is the concentration of NaCl in seawater. The use of raw seawater in mining is becoming relevant in leaching and flotation process. At the same time the use of microorganisms in both processes is gaining attention. For this reason, it is important to study the behavior of adherence of microorganisms to minerals in saline aqueous environments, similar to seawater.

Results: The bacteria showed a higher level of attachment to pyrite in fresh water than in saline water. The Langmuir model fitted better the experimental data obtained in fresh water than in saline water with a coefficient of determination (R²) of 0.85 and 0.61 for fresh and saline water, respectively.

Conclusions: This suggests that the bacteria tend to adhere more as a monolayer in fresh than in saline water in the early stage of adhesion.