The adsorption of Thiobacillus ferrooxidans on coal surfaces

Abstract

The adsorption of Thiobacillus ferrooxidans to coal surfaces has been studied. Adsorption experiments were conducted on coal samples from eight different Eastern coal fields. In all cases the adsorption process was at least 90% complete within the first two minutes following inoculation. The results of these experiments were used to test the validity of two proposed adsorption models. The first model assumes that bacterial adsorption follows second-order irreversible kinetics of the second kind with respect to the concentration of bacteria and substratum surface area in the system. The second model allows for the contribution of reversible adsorption detected in desorption experiments. It was found that the combined reversible-irreversible model more accurately describes the initial stages of adsorption. Rate constants in both models were calculated for each coal sample. The relation of each of these constants to the pyrite concentration in coal is presented and the significance of these relations is discussed. Scanning electron micrographs of inoculated coal samples show that Thiobacillus ferrooxidans selectively adsorb to exposed pyrite phases dispersed throughout the organic coal matrix. Preferential attachment was also observed along topographical faults in the coal surface. Mercury contact angle measurements on coal indicate that the selective adsorption of Thiobacillus ferrooxidans may be attributable to the lower surface free energy of pyrite relative to the organic coal matrix.

A Novel Mineral Flotation Process Using Thiobacillus ferrooxidans

“…Selective adhesion of T. ferrooxidans to pyrite and its interactions. The selectivity of T. ferrooxidans adhesion to pyrite was first suggested when it was observed that the cells adhered to pyrite within coal particles (3,8). The same phenomenon was observed in iron-rich areas of sulfide ores (9).…”

Kinetic Analysis of Streptococcus sanguis Adhesion to Artificial Pellicle

“…Evidence for this type of mechanism has also been presented for the adsorption of Thiobacillus ferroxidans to coal surfaces. The bacterium is held at a finite distance from the surface by the combination of repulsion and attraction, and from that point can dissociate or can either form covalent bonds or expend energy to synthesize polymers that will hold it permanently to the surface (Bagdigian and Myerson, 1986). Similarly, insulin has been found to bind to fat cells reversibly at first until a conformation change in the receptor causes desorption to occur at a much slower rate (Lipkin et al, 1986).…”

Succession Patterns and Physical Niche Partitioning in Microbial Communities from Subsurface Coal Seams

“…Previously coal attachment via biofilms (Raudsepp et al., 2015, Hazrin-Chong and Manefield, 2012) and direct cell interactions (Hazrin-Chong et al., 2014, Bagdigian and Myerson, 1986, Chen and Skidmore, 1988) has been observed for microbes grown on coal aerobically, whereas little examination of this phenomena has been made for native anaerobic microbial consortia (Vick et al., 2016). Here, distinct attached communities of microbes were seen in all three coal communities, whereas scanning electron microscopic visualization of the coal surface identified biofilm formation in only Surat Basin microcosms.…”