Characterisation of mackinawite by Raman spectroscopy: Effects of crystallisation, drying and oxidation

Raman Spectroscopy of Mackinawite FeS in Anodic Iron Sulfide Corrosion Products

“…20 However, mackinawite has been found to be the initial, 8,21 and probably most important corrosion product, of iron in aqueous sulfide solutions as it was observed in reactions carried out over a wide range of pH and temperature. 11,19,[22][23][24] It possesses a tetragonal, layered crystal structure, [25][26][27] and can be synthesized by precipitation from solutions containing Fe 2+ and S 2− solutions, 28,29 or by reaction of sulfide solution with metallic iron. 19,21,26,30 In the field of microbially induced corrosion, sulfatereducing bacteria are known to transform sulfate compounds into iron sulfides, e.g.…”

“…Collected spectra showed a good agreement with the database Raman spectrum of mackinawite, 19,50 but distinct disagreement with data from other authors was found. 29,49,51,52 Due to the lack of availability of a normal mode analysis for mackinawite, no detailed interpretation of the Raman data was possible. Recently, a study by density functional theory (DFT) became available, which reported computed vibrational spectra of mackinawite.…”

“…The use of (in situ and operando) Raman spectroscopy for study corrosion process studies of iron in sulfide rich environments has been already reported. 29,49 In previous work, 19 Raman spectroscopy was used to confirm the nature of iron sulfide films obtained as corrosion products from polarization experiments. Collected spectra showed a good agreement with the database Raman spectrum of mackinawite, 19,50 but distinct disagreement with data from other authors was found.…”

Modification of Mackinawite with L-Cysteine: Synthesis, Characterization, and Implications to Mercury Immobilization in Sediment

“…The mechanism of oxidation of iron sulfides (II) under acidic conditions involves the oxidation of Fe (II) to Fe (III). Researchers have proposed that iron (III) acts as the preferred oxidizing agent for sulfur, ie, the process of electron transfer from sulfur to iron (III) is easier in comparison to transfer to the oxygen (Chiriţă and Descostes, 2006;Burton et al, 2009;Kamei and Ohmoto, 2000;Bourdoiseau et al, 2008). In this work, the FeS consumes less oxygen than the FeS-Cys.…”

“…Piuille et al (1995) reported that the enzyme pyruvate-ferrodoxin oxyreductase was stable in O 2 (atmospheric air) and the L-cysteine groups seemed to provide the oxidation stability. Some investigators have tested iron sulfide oxidation at environmental pH ranges (Burton et al, 2009;Bourdoiseau et al, 2008). Most of the literature is related to the oxidation of reduced iron sulfide compounds such as pyrite, troilite, and pyrrhotite under acidic conditions, for solving acid mine drainage issues (Moses et al, 2003).…”