Preparation of iron-containing hectorite-like swelling silicate

Iron-containing hectorite-like layered silicate was synthesized by the reaction of LiF, Mg(OH) ₂, colloidal silica, and FeCl ₃ in aqueous suspension at 100°C for 2 days. From X-ray diffraction and infrared spectroscopic analysis, the formation of hectorite-like layered silicate was shown. Dimethyldioctadecylammonium and 1,1′-dimethyl-4, 4′bipyridinium (methyl viologen) ions were intercalated by cation-exchange reactions into the interlayer space of the iron-containing silicate. The intercalated amounts of both cationic species were larger compared to iron-free layered silicate, showing increase in the layer charge density of the silicate by the incorporation of iron(III). The increase in the layer charge was thought to be derived from isomorphous substitution of silicon(IV) by iron(III) in the silicate layer. The structural iron(III) was reduced to iron(II) by reaction with sodium dithionite, which was shown by a color-change (yellow to green) and the increase in the intercalated amounts of dimethyldioctadecylammonium and 1,1′-dimethyl-4,4′bipyridinium ions.