Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans

Abstract

Massive pyrite (FeS₂) electrodes were potentiostatically modified by means of variable oxidation pulse to induce formation of diverse surface sulfur species (S(n)²⁻, S⁰). The evolution of reactivity of the resulting surfaces considers transition from passive (e.g., Fe(1-x )S₂) to active sulfur species (e.g., Fe(1-x )S(2-y ), S⁰). Selected modified pyrite surfaces were incubated with cells of sulfur-oxidizing Acidithiobacillus thiooxidans for 24 h in a specific culture medium (pH 2). Abiotic control experiments were also performed to compare chemical and biological oxidation. After incubation, the attached cells density and their exopolysaccharides were analyzed by confocal laser scanning microscopy (CLMS) and atomic force microscopy (AFM) on bio-oxidized surfaces; additionally, S(n)²⁻/S⁰ speciation was carried out on bio-oxidized and abiotic pyrite surfaces using Raman spectroscopy. Our results indicate an important correlation between the evolution of S(n)²⁻/S⁰ surface species ratio and biofilm formation. Hence, pyrite surfaces with mainly passive-sulfur species were less colonized by A. thiooxidans as compared to surfaces with active sulfur species. These results provide knowledge that may contribute to establishing interfacial conditions that enhance or delay metal sulfide (MS) dissolution, as a function of the biofilm formed by sulfur-oxidizing bacteria.

Controlling Electrochemical Lithiation/Delithiation Reaction Paths for Long-cycle Life Nanochain-structured FeS2 Electrodes

“…These Li2FeS2 can be further oxidized to FeS2, FeS and Li2Sx at S10b). These results are in good agreement with the Raman measurements and CV results described in the equations S1 and S2 of Table S3 [39,40]. During charging process (Fig.…”

Insights into the enhancement mechanism coupled with adapted adsorption behavior from mineralogical aspects in bioleaching of copper-bearing sulfide ore by Acidithiobacillus sp.

“…The "direct contact" and "indirect contact" bioleaching mechanisms were derived from these two different microenvironments. 25,27 The role of the attached biomass in bioleaching of copperbearing sulde ore was characterized by the aspects of iron and sulfur metabolisms.…”

Comparison Analysis of Coal Biodesulfurization and Coal’s Pyrite Bioleaching with Acidithiobacillus ferrooxidans

“…Furthermore, some researches proposed a combination of direct and indirect mechanism was probably responsible for its oxidation [ 16 , 17 ]. During its oxidation, the pyrite is degraded via the main intermediate thiosulfate and consequently oxidized via tetrathionate and other polythionates, finally to sulfate with elemental sulfur and jarosite being a side or precipitation product [ 14 , 18 , 19 ]. Many investigators agreed that the deposited jarosite and the sulfur-rich layers onto the surface of pyrite might prevent the contact of the microorganisms and hinder its oxidation process [ 20 – 22 ].…”