Study of the Adhesion Mechanism of Acidithiobacillus ferrooxidans to Pyrite in Fresh and Saline Water

Abstract

In the present work electrostatic forces are evaluated as the cause of attachment of Acidithiobacillus ferrooxidans to pyrite. Streaming potential of A. ferrooxidans and pyrite was measured in two environment, fresh water and saline water (water with 35 g/L of NaCl) at different pH's values. At the same time, attachment kinetics of A. ferrooxidans to pyrite were carried out in fresh and saline water at pH 4. The results showed that A. ferrooxidans and pyrite present lower streaming potential (comparing absolute values) in saline water than in fresh water, indicating the compression in the electric double layer caused by Cl- and Na+ ions. Simultaneously, it was determined that the bacteria present a higher attachment to pyrite in fresh water than in saline water. This suggests that electrostatics forces do not play a leading role in the adhesion mechanism.