The FT-IR spectra of banana peel material before and after
cadmium ion biosorption are shown in Figs. 6 to 7. These
spectra were obtained from scanning in the range of 400-4000
cm-1. The band of banana peel represented overlapping of O-H
and N-H stretching vibration at 3365 cm-1 While the band
represented C=O stretching vibration of carboxylic acids at 1731
cm-1
.
The significant shifts of these specific peaks to the higher
wave number after the cadmium ions biosorption suggested that
chemical interactions between the cadmium ions and the amide
groups occurred on the biomass surface. The band of banana
peel shifted to 3416 cm-1 indicating that hydroxyl, carboxyl and
amide groups were involved in the biosorption. The spectra of
banana peel at 1731 cm-1 become smoother and a band of
banana at 1427 cm-1 appeared, which would resulted from the
complexation of cadmium ions with the functional groups from
protein. These results indicated that carboxyl, hydroxyl and
amide groups on the banana peel surface were involved in the
biosorption of the cadmium ions.