ENVIRONMENTS OF IRON IN FE-SILICATES SYNTHESIZED BY THE RAPID CRYSTALLIZATION METHOD

Pentasil-type Fe-silicates with different iron contents were synthesized using the rapid crystallization method. The physical and chemical properties of the Fe-silicates were investigated by means of various spectrometries, and the environments of iron in the Fe-silicate crystals are discussed. Almost all of the iron did not exist on the ion-exchange sites in the Fe-silicate crystals. Both the ion-exchange capacity and the unit-cell volume ofFe-silicates increased with an increase in the iron content. The IR spectra of the Fe-silicates showed an absorption band due to the silanol groups which were demonstrated to he formed by elimination of a part of the iron atoms from the framework. The NMR and UV spectra also provided evidence for the isomorphous substitution of iron(III) ions in the silicate framework. © 1993 Academic Press, Inc.