Table 11 Main peak of the FTIR spectrum of biodiesel and their assignment
Assignment | Wavelength peak, cm−1 | |
|---|---|---|
Range | Actual | |
C–H stretch (alkyl) | 2915–2935; 2845–2865 | 2920; 2849 |
C–O stretch (ester) | 1725–1750 | 1749 |
C=H stretch (carboxylic acid) | 1700–1725 | 1719 |
C–H bend (\({\text{CH}}_{2} /{\text{CH}}_{3}\)) | 1425–1465 | 1460, 1440 |
C–H bend (\({\text{CH}}_{3}\)) | 1370–1380 | 1370 |
Aryl-O stretch (aromatic ethers) | 1230–1270 | 1249 |
X-O group (\({\text{SO}}_{2}\)) | 1180–1200 | 1200, 1180 |
C–H out of plane bend (aryl) | 670–900 | 729 |