Composition and structure of an iron-bearing, layereddouble hydroxide (LDH) - Green rust sodium sulphate

TY - JOUR

T1 - Composition and structure of an iron-bearing, layereddouble hydroxide (LDH) - Green rust sodium sulphate

AU - Christiansen, Bo C.

AU - Balic Zunic, Tonci

AU - Petit, Pierre-Olivier

AU - Frandsen, Cathrine

AU - Mørup, Steen

AU - Geckeis, Horst

AU - Katerinopoulou, Anna

AU - Stipp, Susan Louise Svane

PY - 2009

Y1 - 2009

N2 - Mixed-valent Fe(II),Fe(III)-layered hydroxide, known as green rust, was synthesized from slightly basic, sodium sulphate solutions in an oxygen-free glove box. Solution conditions were monitored with pH and Eh electrodes and optimized to ensure a pure sulphate green-rust phase. The solid was characterised usingMo¨ssbauer spectroscopy, X-ray diffraction, scanning electron microscopy and atomic force microscopy. The composition of the solution from which the green rust precipitated was established by mass and absorption spectroscopy. The sulphate form of green rust is composed of brucite-like layers with Fe(II) and Fe(III) in an ordered distribution. The interlayers contain sulphate, water and sodium in an arrangement characteristic for the nikischerite group. The crystal structure is highly disordered by stacking faults. The composition, formula and crystallographic parameters are: NaFe(II)6Fe(III)3(SO4)2(OH)18•12H2O, space group P-3, a = 9.528(6)Å, c = 10.968(8)Å andZ = 1. Green rust sodium sulphate, GRNa,SO4, crystallizes in thin, hexagonal plates. Particles range from less than 50 nm to 2 µm in diameter and are 40 nm thick or less. The material is redox active and reaction rates are fast. Extremely small particle size and high surface area contribute to rapid oxidation, transforming green rust to an Fe(III)-phase within minutes.

AB - Mixed-valent Fe(II),Fe(III)-layered hydroxide, known as green rust, was synthesized from slightly basic, sodium sulphate solutions in an oxygen-free glove box. Solution conditions were monitored with pH and Eh electrodes and optimized to ensure a pure sulphate green-rust phase. The solid was characterised usingMo¨ssbauer spectroscopy, X-ray diffraction, scanning electron microscopy and atomic force microscopy. The composition of the solution from which the green rust precipitated was established by mass and absorption spectroscopy. The sulphate form of green rust is composed of brucite-like layers with Fe(II) and Fe(III) in an ordered distribution. The interlayers contain sulphate, water and sodium in an arrangement characteristic for the nikischerite group. The crystal structure is highly disordered by stacking faults. The composition, formula and crystallographic parameters are: NaFe(II)6Fe(III)3(SO4)2(OH)18•12H2O, space group P-3, a = 9.528(6)Å, c = 10.968(8)Å andZ = 1. Green rust sodium sulphate, GRNa,SO4, crystallizes in thin, hexagonal plates. Particles range from less than 50 nm to 2 µm in diameter and are 40 nm thick or less. The material is redox active and reaction rates are fast. Extremely small particle size and high surface area contribute to rapid oxidation, transforming green rust to an Fe(III)-phase within minutes.

KW - Faculty of Science

U2 - 10.1016/j.gca.2009.03.032

DO - 10.1016/j.gca.2009.03.032

M3 - Journal article

SN - 0016-7037

VL - 73

SP - 3579

EP - 3592

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

IS - 12

ER -