Mechanisms of formation and transformation of Ni–Fe layered double hydroxides in and containing aqueous solutions

Abstract : The oxidation of (Ni,Fe)(OH)2 suspensions in the presence of and anions can lead whether to the SO3-form or to the SO4-form of the Ni(II)–Fe(III) layered double hydroxides (LDHs). The hydroxysulphite, like the corresponding Fe(II)–Fe(III) compound, is characterised by a M(III)/M(II) ratio of 1/3 and forms from the initial hydroxide. If P=[Fe]/[Ni]=1/3, the end product is then . If P>1/3, the SO3-LDH still contains Fe(II) and the oxidation process goes on. The SO3-LDH tends to transform into a mixture of ferrihydrite and SO4-LDH. The hydroxysulphate, like the corresponding Fe(II)–Fe(III) compound, is characterised by a M(III)/M(II) ratio of 1/2 and obeys to the composition . The formation of the SO4-LDH is favoured by the oxidation of into anions, whereas the formation of ferrihydrite is the process that takes place if the initial anions are stable, e.g. Cl−.
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Submitted on : Tuesday, December 18, 2018 - 11:28:09 AM
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Philippe Refait, Mustapha Abdelmoula, Lilian Simon, Jean-Marie Génin. Mechanisms of formation and transformation of Ni–Fe layered double hydroxides in and containing aqueous solutions. Journal of Physics and Chemistry of Solids, Elsevier, 2005, 66 (5), pp.911-917. ⟨10.1016/j.jpcs.2004.12.003⟩. ⟨hal-01958789⟩

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