Table 10. Summary of infrared spectral bands observed in the native corncob, DY27-loaded corncob, and DY27 dye.

IR band frequency [cm-1]			Functional group assignment	Reference
Native corncob	DY27-loaded corncob	DY27 dye
3428	3421	3498	O-H stretching	[60]
2916	2910	-	Symmetric stretching of C-H	[61]
1732	1734	-	C = O stretching vibration of hemicellulose	[62]
1653	1654	1664	C = O stretching of amide I of proteins	[63]
1603	1603	1598	Aromatic skeletal vibration + C = O stretching	[64]
1515	1514	-	Aromatic skeletal vibration of lignin	[64]
-	-	1507	N = N stretching	[65]
-	1458	1464	C = C stretching of aromatic rings of dye	[65]
1426	1430	1438	C-H in plane deformation with aromatic ring stretching	[66]
1374	1375	-	Symmetric C-H deformation of cellulose	[67]
1250	1248	-	C-O stretching of hemicellulose	[68]
-	-	1211, 1188	Amine C-N stretching	[69]
1160	1163	-	C-O-C stretching of glycosidic linkages	[70]
1070	1085	-	C-O deformation of secondary alcohols and aliphatic ethers	[64]
1049 shoulder	1051 shoulder	1049	C-O stretching vibrations of cellulose S = O stretching of sulfonate groups	[70] [63]
900	898	-	Antisymmetric out-of-plane ring stretching of cellulose	[66]