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

Abstract

In the present work, the streaming potential of A. ferrooxidans and pyrite was measured in two environments: fresh and saline water (water with 35 g/L of NaCl) at different pH values. Also, attachment kinetics of A. ferrooxidans to pyrite was studied in fresh and saline water at pH 4. The results show that A. ferrooxidans and pyrite had lower streaming potentials (comparing absolute values) in saline water than in fresh water, indicating the compression in the electrical double layer caused by Cl− and Na+ ions. It was also determined that the bacteria had a higher level of attachment to pyrite in fresh water than in saline water. The high ionic strength of saline water reduced the attractive force between A. ferrooxidans and pyrite, which in turn reduced bacterial attachment. Electrostatic interactions were determined to be mainly repulsive, since the bacteria and mineral had the same charge at pH 4. Despite this, the bacteria adhered to pyrite, indicating that hydrophobic attraction forces and Lifshitz–van der Waals interactions were stronger than electrostatic interactions, which caused the adhesion of A. ferrooxidans to pyrite.

Preliminary Study on the Surface Modification of Lignite and Bioflotation by White-Rot Fungi Hypocrea lixii AH

“…Apart from these traditional methods, bioflotation has received increasing attention due to its strong selectivity, environmental friendliness, and economic efficiency [7]. In principle, microbial cells and their metabolites can be used as flotation collectors [8,9], foaming agents [10], inhibitors [11][12][13], as well as modification agents for bioflotation processes that achieve selective separation through adhesion and chemical reactions [11,14,15]. In the past decades, fungi have emerged as a potential tool in the bioflotation process, with studies highlighting the effectiveness of Mycobacterium phlei and Rhodotorula mucilaginosa as collectors, wherein their hydrophobicity, influenced by pH, dissolved ions, cell concentration, and other parameters, played a crucial role [8,16].…”