Table 3: Main functional groups in the IR spectrum of biomass after adsorption.

Wavenumber (cm‒1) Intensity Functional Group Group Name
3304.06 Medium ‒OH Hydroxyl/Phenol
2885.51 Strong C‒H Alkane
1762.92 Strong C=O Carboxylic acid
1751.36 Strong C=O Carboxylic acid
1734.01 Strong C=O Carboxylic acid
1724.36 Strong C=O Carboxylic acid
1654.92 Strong N‒C=O Amide
1595.13 Strong C‒N Amide 1° bending vibration
1425.40 Medium C‒O‒H Carboxylic acid bending
1246.02 Medium C‒O‒C Ether
1043.49 Medium CO‒O‒CO Anhydride