Table 1.
Data on nitrogenous dyes and adsorption capacities of MMT (20 mg/30 mL).
| Dye (Conc.) | Solution pH; pKa | Molecular structure | Molecular radius/(Å) | Adsorption capacity/(mg/g) | Cation Exchange Capacity/(mmol/g) |
|---|---|---|---|---|---|
| methylene blue (0.1 mmol/L, 32.0 mg/L) | 7.1 ± 0.13; <1.0 |
 (M.Wt: 319.85) |
4.25 | 57.5 | 0.1782 |
| rhodamine B (0.05 mmol/L, 24.0 mg/L) | 2.9 ± 0.06; 3.7 |
 (M.Wt: 479.02) |
5.24 | 21.9 | 0.0457 |
| sulforhodamine G (0.033 mmol/L, 18.4 mg/L) | 6.60 ± 0.16; 1.5 |
 (M.Wt: 552.59) |
5.56 | 21.9 | \ |
| rhodamine B (0.05 mmol/L, 24.0 mg/L) | 6.4 ± 0.17; 3.7 |
 (M.Wt: 479.02) |
5.21 | 17.2 | 0.0359 |
| orange II (0.017 mmol/L, 5.8 mg/L) | 6.8 ± 0.08; 11.4 |
 (M.Wt: 350.32) |
4.51 | 0 | \ |