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. 2023 Nov 2;9(11):e21862. doi: 10.1016/j.heliyon.2023.e21862

Table 2.

Langmuir, Freundlich, Elovich isotherm parameters, correlation coefficient, and chi-square for the adsorption of Ni(II) on different adsorbents.

 Type of adsorbent
Parameter WCS-Raw WCS-NaOH WCS-CA WCS-AM WCS-Si
Langmuir isotherm
qm (mg/g) 29.06 26.46 52.08 40.32 158.73
kL (L/mg) 0.090 0.061 0.151 0.098 0.470
R2 0.9994 0.9882 0.9987 0.9991 0.9995
RL 0.1 0.18 0.062 0.119 0.021
χ2 0.035 0.413 0.590 0.061 3.540
Freundlich isotherm
n 3.721 3.095 3.969 2.853 3.314
kF (mg/g)/(mg/L)1/n 8.0125 5.4141 16.6915 8.595 50.38
R2 0.9598 0.9890 0.9713 0.9677 0.9571
χ2 0.232 0.063 0.448 0.378 7.409
Elovich isotherm
qmE (mg/g) 7.37 8.01 11.75 13.04 35.84
KE (L/mg) 1.4581 0.5504 3.5151 0.6803 7.0736
R2 0.9634 0.9576 0.9774 0.9635 0.9606
χ2 1.598 0.953 3480 1.566 37.961