The substitution of Fe2+ ions by Ni2+ ions in the green rust 2 compound studied by Mössbauer effect

Abstract

Green rust 2 is usually obtained by oxidizing an initial mixture of FeSO4 and NaOH solutions and a complete oxidation leads mainly towards γ oxyhydroxide known as lepidorocite. By adding some NiSO4 one can stop at the first stage and Mossbauer spectra reveral only ferric doublets. This implies that the initial formula 4Fe(OH)2, 2FeOOH, FeSO4 of green rust 2 must be replaced byxNi(OH)2, (6−x)FeOOH, NiSO4, wherex scans from 2 to 4. It also means that all initial ferrous ions become oxidized into the ferric state leaving the Ni2+ ions unchanged. Therefore the end product of oxidation is the nickel containing green rust 2 at the place of the usual lepidocrocite.