X-ray absorption spectroscopy study of H2S sorption on iron-rich soil: Characterization of iron–sulfur species

Iron-rich soil after sorption of H2S was characterized using X-ray absorption near-edge structural (XANES) and extended X-ray absorption fine structure spectroscopy (EXAFS) for determination the possible products in the present work. EXAFS revealed that the main Fe–S species in the sulfided sample were FeS (troilite) and Fe1−xS (pyrrohotite). Iron in the sulfided sample was found to possess a Fe–S bond distance of 2.36 Å and a Fe–O bond distance of 1.72 Å in the Fe–K-edge spectra whereas the Fe–S bond distance of 2.25 Å was determined in the sulfur K-edge spectra. In the second shells, the bond distance of Fe–O–Si or Fe–O–Al with 3.28 Å was also observed. No FeS2 (pyrite) was included in the sulfided sample. The formation of Fe1−xS was probably attributed to the presence of Fe3O4, a type of spinel structure with a lattice deficiency.