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Table 4 Signal assignment and relative intensities in the FTIR spectra of the lignin samples

From: Adsorption and mechanism of cellulase enzymes onto lignin isolated from corn stover pretreated with liquid hot water

Peak (cm−1) Assignment Control S = 3.6 S = 3.9 S = 4.2
3446 O–H stretching vibration in OH groups (R–OH, Ar–OH) 14.98 14.16 15.93 22.17
2925 C–H stretching vibrations 18.19 11.72 11.90 14.02
2849 6.73 3.83 3.67 4.95
1770 Unconjugated carbonyl groups (C=O stretch) 0.70 1.22 1.56 1.65
1653 Conjugated carbonyl groups (C=O stretch) 63.01 75.08 80.54 95.00
1458 C–H vibrations in –CH3 28.40 20.01 20.91 24.43
1370 Phenolic hydroxyl groups (Ar–OH) 5.32 5.03 5.20 10.93
1335 R–OH in the lignin 6.25 3.79 3.89 4.82
465 The 2 or 2, 3, 4 overlay substitution of benzene ring 404.80 408.19 421.17 569.49
  1. The relative intensity was calculated as the ratio of the intensity of the band to the intensity of the band at 1795 cm−1
  2. S stands for the pretreatment severity