3.1.5. FTIR
In Fig. 5, in situ FTIR spectra are shown for the pristine zeo- lite 13X and amine-grafted sample ZX10. The pristine sample presented peaks in the range of 3750–3500cm−1 attributed to hydroxyl groups belonging to the surface of the adsorbent or physisorbed water. The spectrum also suggests the formation of hydrogen bonds, judging from the peaks observed in the range of 3250–3400 cm−1 . Note that at high temperature (pristine sample), the hydrogen bonds are not found. A large peak near 2330 cm−1 is related to physisorbed CO2 in both samples [20,21], which is present in both temperatures with different intensities.
The peaks found in the region from 1200 to 1700 cm−1 (Fig. 5b) are relevant because they provide important evidence of amine impregnation and formation of carbamate species (characteristic of chemical adsorption). By comparing the spectra of the pristine and grafted samples under vacuum, the presence of an additional peak is observed for ZX10 at 1615 cm−1 , relative to the incorpora- tion of amine groups (protonated form) on the adsorbent surface [22,23].
3.1.5. FTIRIn Fig. 5, in situ FTIR spectra are shown for the pristine zeo- lite 13X and amine-grafted sample ZX10. The pristine sample presented peaks in the range of 3750–3500cm−1 attributed to hydroxyl groups belonging to the surface of the adsorbent or physisorbed water. The spectrum also suggests the formation of hydrogen bonds, judging from the peaks observed in the range of 3250–3400 cm−1 . Note that at high temperature (pristine sample), the hydrogen bonds are not found. A large peak near 2330 cm−1 is related to physisorbed CO2 in both samples [20,21], which is present in both temperatures with different intensities.The peaks found in the region from 1200 to 1700 cm−1 (Fig. 5b) are relevant because they provide important evidence of amine impregnation and formation of carbamate species (characteristic of chemical adsorption). By comparing the spectra of the pristine and grafted samples under vacuum, the presence of an additional peak is observed for ZX10 at 1615 cm−1 , relative to the incorpora- tion of amine groups (protonated form) on the adsorbent surface [22,23].
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