| Two-Parameter Isotherm |
| Langmuir |
 qmax is a parameter
that reflects monolayer formation, KL is
the adsorption equilibrium constant |
qmax (mg/g) |
322 |
0.98 |
|
KL (L/mg) |
1.80 × 10–3
|
| Freundlich |
 Kf is a constant
for the relative adsorption capacity, 1/nf is a constant indicative of surface heterogeneity |
Kf (L/g) |
1.9 |
0.97 |
| 1/nf (−) |
0.71 |
| D-R |
qe = (qm) exp. (−Kad ε2) ε = RT (1 + (1/Ce)) Kad is a constant related
to adsorption energy, qm is the theoretical
adsorption capacity. |
qm (mg/g) |
231 |
0.99 |
|
Kad (mol2/kJ2) |
0.036 |
| Three-Parameter Isotherm |
| Langmuir–Freundlich |
 qmax, KLF and βLF are the max. adsorption
capacity, the equilibrium constant, and the heterogeneity parameter,
respectively. |
qmax (mg/g) |
199 |
0.99 |
|
KLF (L/mg) |
0.5 ×
10–2
|
| βLF (−) |
1.84 |
| Sips |
 qmax, KS and ns are the
Sips max. adsorption capacity, equilibrium constant, and the model
exponent, respectively |
qmax (mg/g) |
196 |
0.99 |
|
Ks (L/mg) |
4.90 × 10–5
|
|
ns (−) |
1.84 |
| Redlich–Peterson |
 qmax, Ks and βs are the isotherm constants |
qmax (L/mg) |
0.47 |
0.99 |
|
Ks (mg/g)g
|
7.8 × 10–7
|
| βs (−) |
2.12 |
| Toth |
 Ke, Kl, and n are Tóth max.
adsorption capacity, Tóth equilibrium constant, and Tóth
model exponent, respectively |
Ke (mol*L/mg*mg) |
0.86 |
0.99 |
|
KL (L/mg) |
6.90 ×
10–6
|
|
n (−) |
1.79 |
| Four-Parameter Isotherm |
| Baudu |
 qmax and bo are the Baudu max. adsorption capacity and
the equilibrium constant, respectively, x and y are the Baudu parameters |
qmax (mg/g) |
171 |
0.99 |
|
bo (−) |
5.17
× 10–5
|
|
X (−) |
19.7 × 10–3
|
|
Y (−) |
8.45
× 10–1
|
