Table 6.
Non-linear isotherm parameters for the adsorption of Pb(II) onto the natural and modified clay adsorbents.
| Model Parameter | Adsorbent |
|||
|---|---|---|---|---|
| Bentonite | Organobentonite | Kaolin | Organokaolin | |
| Langmuir | ||||
| KL (L/mg) | 0.2743 | 1.0247 | 0.4149 | 0.4447 |
| qm (mg/g) | 14.713 | 18.752 | 4.1907 | 2.2591 |
| R2 | 0.9965 | 0.9072 | 0.9659 | 0.9875 |
| RMSE | 0.4377 | 2.485 | 0.4078 | 0.1172 |
| χ2 | 0.0479 | 1.544 | 0.0554 | 0.0046 |
| Freundlich | ||||
| KF(mg(1-1/n)11/n/g) | 3.770 | 7.380 | 1.3980 | 0.8432 |
| n | 1.90 | 2.82 | 2.61 | 3.07 |
| R2 | 0.9926 | 0.9913 | 0.9531 | 0.9705 |
| RMSE | 0.6325 | 0.7632 | 0.4781 | 0.1799 |
| χ2 | 0.1000 | 0.1456 | 0.0762 | 0.0108 |
| Dubinin-Radushkevich(D-R) | ||||
| qm | 10.139 | 11.719 | 3.244 | 1.8885 |
| β (mol2kJ2) | 0.07561 | 0.05472 | 0.9426 | 0.20604 |
| E (kJ/mol) | 4.775 | 67.61 | 3.128 | 3.395 |
| R2 | 0.9462 | 0.9576 | 0.7483 | 0.9040 |
| RMSE | 30.711 | 17.979 | 10.750 | 3.028 |
| χ2 | 0.9466 | 0.3242 | 0.1159 | 0.0092 |