SYNTHESIS AND CHARACTERIZATION OF Zn-SUBSTITUTED SAPONITE (SAUCONITE)

Sauconites were synthesized hydrothermally from a homogeneous gel with stoichiometric chemical composition in a temperature range of 100-200°C for up to 14 d at autogenous pressure. The synthetic products were characterized by XRD, SEM, TEM, ICP-AES, FT-IR and XPS. The well-crystallized sauconite without impurities was obtained after 100°C treatment. At 150 and 200°C, sauconite coexisted with small amount of hemimorphite (Zn 4 Si 2 O 7 (OH) 2 .H 2 0) and willemite (Zn 2 SiO 4 ). The octahedral coordination of Zn in synthesized sauconite was confirmed by FT-IR and XPS spectra, comparing with those of natural mica containing Zn in the octahedral layer (hendricksite). The FT-IR spectra of synthetic sauconite showed the characteristic bands at 660 cm -1 for Zn-O vibration and 3635 cm -1 for 3Zn-OH stretching in the octahedral sheets, which are comparable to those of hendricksite. The Zn(3p) peak of sauconite in XPS spectrum was observed which corresponded with that of hendricksite. These results indicated that Zn in sauconite was coordinated octahedrally as Zn in hendricksite.