Influence of silicate ions on the formation of goethite from green rust in aqueous solution

We investigated the influence of silicate ions on the formation of goethite converted from hydroxysulphate green rust, which was synthesized by neutralizing mixted solution of Fe2(SO4)3 and FeSO4 with NaOH solution, by O2 in an aqueous solution. The pH and oxidation–reduction potential of the suspension and the Fe and Si concentrations in supernatant solutions were analyzed. X-ray diffraction results for the solid particles formed during the conversion were consistent with the results of the solution analyses. The results indicated that silicate ions suppressed the conversion from green rust to α-FeOOH and distorted the linkages of FeO6 octahedral units in the α-FeOOH structure.