Particulate pyrite formation by the Fe3+/HS- reaction in aqueous solutions: Effects of solution composition

Dawei Wei, K. Osseo-Asare

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Microsize particles of pyrite were synthesized by reaction of ferric ions with sulfide ions in aqueous solutions. The reaction products of the synthesis experiments were characterized by X-ray diffraction and electron-optical techniques. The formation of pyrite was affected strongly by the pH and redox potential (Eh) of the working solutions. Pyrite, with a mean particle diameter of 1.5 μm, formed in the pH range 3.6-5.7 at Eh values of ≈0 V (-0.05-0.01 V). The intermediate products of elemental sulfur and FeS (or Fe(HS)+) were identified as essential precursors for pyrite formation. Eh-pH diagrams for the S-H2O and Fe-S-H2O systems indicated that the solid species FeS (or the soluble complex Fe(HS)+) and elemental sulfur are both thermodynamically stable under the conditions where pyrite forms. The inability to form pyrite below ≈pH 3.6 is attributed to undersaturation of FeS or the absence of Fe(HS)+. In contrast, the inhibition of pyrite formation above pH≈5.7 is ascribed to the corresponding Eh conditions which make FeS unstable relative to FeOOH. In addition, it was demonstrated that nanoparticles of pyrite could be obtained by lowering the concentrations of Fe3+ and HS- in the early stages of the reaction.

Original languageEnglish (US)
Pages (from-to)51-61
Number of pages11
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Issue number1-2
StatePublished - Nov 1 1996

All Science Journal Classification (ASJC) codes

  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry


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