Table 4. Parameter fits of Models of Langmuir, Freundlich, Redlich–Peterson, and Sips to Experimental Data of Caffeine Adsorption.
| caffeine | ||||||
|---|---|---|---|---|---|---|
| two-parameter
models | ||||||
| Langmuir
model |
Freundlich
model |
|||||
| sample | Qo (mg g–1) | KL (mL mg–1) | R2 | KF (mL g–1) | 1/n | R2 |
| SBA-15 | 6.94 | 30.3 | 0.510 | 6.92 | 0.0003 | 0.510 |
| SBA-15-NH2 | 4.45 | 0.029 | 0.856 | 0.4288 | 0.4609 | 0.860 |
| three-parameter models | ||||||||
|---|---|---|---|---|---|---|---|---|
| Redlich–Peterson
model |
Sips
Model |
|||||||
| sample | KRP (mg g–1) | αRP (mL mg–1) | β | R2 | Qo (mg g–1) | KS (mL mg–1) | 1/ns | R2 |
| SBA-15 | 4.84 | 0.424 | 1.14 | 0.510 | 18.6 | 6.32 × 10–7 | 0.0449 | 0.509 |
| SBA-15-NH2 | 1.35 | 0.001 | 1.16 | 0.999 | 22.5 | 0.0004 | 0.5182 | 0.858 |