Band position (cm−1)

Bands assigned

and Functional group

References of the FT-IR bands

Wavenumber (cm−1)/absorptions

Sample S1

Sample S2

Sample S3

3200 - 3460 cm−1

O-H stretching in carbohydrate and lignin

( Popescu et al., 2011a )

3419/62.41

3409/63.15

3408/60.15

3527/67.42

3527/65.54

2842 - 2935 cm−1

C-H stretching (methyl and methylene groups)

( Pandey, 1999 )

2937/85.34

2895/94.38

2938/90.97

1731 - 1739 cm−1

C=O stretching (unconjugated ketones) in hemicellulose

( Shi et al., 2012 ; Yilgor et al., 2013 ; Özgenç et al., 2018 )

1727/84.02

-

1732/87.46

1640 cm−1

Absorbed water

( El Hadidi & Darwish, 2014 )

1645/79.18

1637/74.41

1647/73.54

1625/74.51

1636/72.89

1624/72.43

1595 cm−1

Aromatic skeletal, C=O stretch in lignin

( Han et al., 2020 )

1592/84.11

1595/86.84

1594/87.92

1506 - 1515 cm−1

C=C stretching, Aromatic ring (lignin)

( Bodîrlău & Teacă, 2009 ; Gonultas & Candan, 2018 )

1511/78.06

1508/89.24

1507/89.56

1460 cm−1

C-H asymmetric deformations in -CH3 and -CH2-

( Jahan & Mun, 2006 ; Huang et al., 2012 )

1461/78.27

1461/82.35

-

1425 cm−1

CH2 bending cellulose

( El Hadidi, 2017 )

1426/77.13

1420/83.32

1418/78.53

1375 cm−1

CH bending in cellulose

( Poletto et al., 2012 ; Lionetto et al., 2012 ; El Hadidi, 2017 )

1373/76.37

1384/79.7

1384/53.62

1335 cm−1

OH (plane bending in cellulose ‘amorphous’)

( Colom et al., 2003 ; Lionetto et al., 2012 ; El Hadidi, 2017 )

-

-

1336/78.67

1316 cm−1

CH2 wagging (crystalline cellulose)

( Colom et al., 2003 ; Lionetto et al., 2012 ; El Hadidi, 2017 )

1318/76.94

1320/79.76

1320/79.90

1269 cm−1

guaiacyl ring, C-O in lignin

( Pandey, 1999 ; Popescu et al., 2006 )

1269/72.91

1269/81.77

-

1235 cm−1

Acetyl and carboxyl vibrations and C=O stretching in Xylan and lignin

( Yilgor et al., 2013 )

1233/74.14

-

-

1159 cm−1

C–O–C asymmetric stretching vibrations (Carbohydrate)

( Andriulo et al., 2016 ; Traoré et al., 2018 )

1159/69.09

-

-

897 cm−1

C-H deformation in cellulose

( Zhou et al., 2018 )

896/80.09

895/85.46

863/89.65

806 cm−1

Aromatic C-H (out of planedeformations) in lignin

( Evans, 1991 ; Xing et al., 2015 ; Traoré et al., 2018 )

806/81.23

807/84.77

808/87.07