Table 4.
FT-IR characteristic wavelengths for C.I. C.I. Natural Red 4, marine sponge and hybrid material (dye solution 50 mg/L, contact time 30 min, pH = 7).
| C.I. Natural Red 4 | Hippospongia communis skeleton | Dye/Biopolymer hybrid material | Vibrational assignment |
|---|---|---|---|
| 3400 | 3410 | 3415 | –OH stretching |
| – | 3300 | 3310 | –NH stretching |
| 2930 | 2930 | 2930 | –CH2, –CH3 stretching |
| 1650 | 1630 | 1655 | C=O stretching |
| 1560 | – | 1560 | C=CAr stretching |
| – | 1520 | 1525 | –NH deformational |
| – | 1460 | 1460 | –CH scissors |
| 1400 | 1400 | 1405 | –OH stretching |
| – | 1250 | 1250 | C–N stretching |
| 1080 | 1080 | 1075 | C–O–C stretching |
| 1020 | 1020 | 1020 | C–O stretching |
| 900 | – | 907 | –OH bending |
| 660 | – | 660 | –CHAr deformational |
| 520 | – | 525 |