FT-IR-spectrum exhibited the presence of sulfate bands at 1234, 1135, 1071, 1047 and 996 cm1 (Fig. 1b), characteristic of inorganic chelating bidentate sulfate which are assigned to asymmetric and symmetric stretching frequencies of S---O and SAO bonds with C2v symmetry and m3 and m1 stretching mode of SO4 2 groups [36].