Table 9. Principal Bands of Waste Cooking Oil and Biodiesel.

chemical group and bond type	mode of vibration	∼ wavenumber, cm–1
		biodiesel (FAME)	WCO
moisture, carboxylic acid and alcohol (O–H)	stretching	3473	3473
alkenes and aromatics (=C–H)	stretching	3006	3006
aliphatics (asymmetric C–H)	stretching	2923	2930
aliphatics (symmetric C–H)	stretching	2854	2844
ketones, ester, aldehydes (C–O)	stretching	1744	1748
alkane (C–H in −CH3– and −CH2−)	bending	1458	1459
alkane (C–H in −CH3)	bending	1362	1374
ester (asymmetric C–O in C–C(=O)–O)	stretching	1168	1168
ester (asymmetric C–O in O–C–C)	stretching	1115	1112
aromatic (C–H)	bending	874	870
alkane (C–H)	rocking	723	722