Table 4 Parameters of the isotherm models for the adsorption of U(VI) ions on the sorbent
Model | Parameter | 293 K 2 h | 293 K 24 h | 313 K 2 h | 313 K 24 h | 333 K 2 h | 333 K 24 h |
|---|---|---|---|---|---|---|---|
Langmuir-Freundlich | K L-F (dm3/mol) | 254.1 | 6760.8 | 494.3 | 4183.4 | 6006.2 | 7707.3 |
n | 0.459 | 0.721 | 0.542 | 0.607 | 0.748 | 0.768 | |
q max (mol/g) | 6.73 × 10−5 | 6.8 × 10−5 | 7.34 × 10−5 | 7.32 × 10−5 | 7.69 × 10−5 | 7.70 × 10−5 | |
R 2 | 0.9912 | 0.9945 | 0.9951 | 0.9958 | 0.9915 | 0.9943 | |
Dubinin-Radushkevich | K D-R (mol2/kJ2) | 3.88 × 10−9 | 3.81 × 10−9 | 3.43 × 10−9 | 3.3 × 10−9 | 3.2 × 10−9 | 4.35 × 10−9 |
Q m (mol/g) | 3.47 × 10−6 | 3.9 × 10−6 | 2.88 × 10−5 | 3.3 × 10−6 | 2.22 × 10−6 | 3.38 × 10−6 | |
E (kJ/mol) | 11.35 | 11.61 | 11.76 | 13.38 | 13.56 | 13.72 | |
R 2 | 0.9083 | 0.9963 | 0.9929 | 0.9674 | 0.9796 | 0.9882 | |
Temkin | b T (J/mol) | 131.6 | 128.3 | 109.7 | 110.5 | 112.8 | 111.8 |
K T (dm3/g) | 0.970 | 0.956 | 0.947 | 0.952 | 1.002 | 1.005 | |
R 2 | 0.9753 | 0.9698 | 0.9898 | 0.9852 | 0.9628 | 0.9851 | |
Freundlich | K F (dm3/mol) | 57.5 | 781.05 | 475.90 | 347.78 | 239.68 | 213.88 |
n | 0.36 | 0.357 | 0.41 | 0.55 | 0.66 | 0.8 | |
R 2 | 0.9642 | 0.9641 | 0.9637 | 0.9555 | 0.9622 | 0.9668 |