Synthesis and characterization of new iron(III) layered hydroxides

A new layered iron hydroxide was synthesized by a wet chemical technique, by which aqueous ferrous sulfate solution was gradually oxidized by using sodium carbonate at 283 ∼ 333 K. Obtained yellowish precipitates identified by X-ray powder diffraction had a similar structure to the layered double hydroxides. The observed interlayer spacing was about d=0.74 nm. Electron micrographs showed that the particles had plate-like morphology. Electron diffraction pattern of the plate-like particles had hexagonal symmetry, when the electron beam was aligned normal to the planes. Mössbauer spectrum suggested that all iron ions were paramagnetic Fe³⁺ states with large quadrupole splittings at room temperature. These results show that the obtained new layered iron hydroxide cotains only Fe(III) ion species. Water vapor adsorption curves of the sample oxidized át 291 K showed high adsorption value (19 wt%) by unit weight.