FTIR peak values of RM and the study of Khurana, R. K. et al., 2017 and Vo et al., 2017 (wave number; cm⁻¹).

Functional group (wave number; cm−1)	RM (cm−1)	MS (cm−1)37	PM (cm−1)38
O–H (3200–3400)	3371.06	3399	3397
C–H (2800–3000)	2918.34	2932.80	2902
C O (1650–1800)	1649.79	1636.75	1649
C C (1600–1670)	1622.30	—	1621
CH–CH (1450–1500)	1494.88	1497.10	—
C–O (1020–1275)	1255.17	1253	1256
C–O–C (1000–1300)	1199.35	—	1195
C–C (1020–1075)	1021.07	1023.22	—
O–H (deformation)	1095.93	—	1095