Table 1. Linear regression equations and coefficient of determination (R2) for Freundlich, Langmuir and Dubinin-Radushkevich isotherm models for the metal ions adsorption on unmodified and modified maize husk of 450 µm and 850 µm particle sizes.


Metal
ions

Unmodified

Modified

450 µm

850 µm

450 µm

850 µm

Freundlich Isotherm

Cd

Y = 2.6421 x -5.3968
(R2 = 0.9775)

Y = 1.6218 - 2.5328
(R2 = 0.9875)

Y = 0.2926 x +2.0573
(R2 = 0.9743)

Y = 0.9686 x +0.0876
(R2 = 0.9334)

Pb

Y = 1.8178 x -3.178
(R2 = 9748)

Y = 2.1734 x -4.3554
(R2 = 0.9932)

Y = 0.2506 x +2.0689
(R2 = 0.9609)

Y = 1.0631 x +0.4862
(R2 = 0.9952)

Zn

Y = 1.1595 x -0.3138
(R2 = 0.9846)

Y = 1.3107 x -0.7849
(R2 = 0.9846)

Y = 0.0245 x +2.7883
(R2 = 0.6279)

Y = 0.312 x +1.977
(R2 = 0.9768)

Langmuir Isotherm

Cd

Y = -0.0066 x +9.593
(R2 = 0.9621)

Y = -0.003 x +7.7867
(R2 = 0.8345)

Y = 0.0012 x +0.1344
 (R2 = 0.9795)

Y = 0.00008 x +0.9488
(R2 = 0.0233)

Pb

Y = -0.0046 x +10.038
(R2 = 0.8502)

Y = -0.007 x +14.646
(R2 = 0.9341)

Y = 0.0014 x +0.1902
(R2 = 0.9742)

Y = 0.00008 x +2.0808
(R2 = 0.1238)

Zn

Y = -0.0003 x +0.9212
(R2 = 0.6266)

Y = -0.0006 x +1.208
(R2 = 0.8414)

Y = 0.0013 x +0.0339
(R2 = 0.9966)

Y = 0.0012 x +0.1655
(R2 = 0.9887)

Dubinin-Radushkevich Isotherm

Cd

Y = -0.9121 x +8.138
(R2 = 0.9654)

Y = -0.6514 x +7.0375
(R2 = 0.9988)

Y = -0.022 x +6.6179
(R2 = 0.8743)

Y = -0.1654 x +7.079
(R2 = 0.9121)

Pb

Y = -0.7767 x +7.2452
(R2 = 0.9765)

Y = -0.9387 x +7.3686
(R2 = 0.9876)

Y = -0.029 x +6.473
(R2 = 0.8875)

Y = -0.2879 x +6.9124
(R2 = 0.9943)

Zn

Y = -0.185 x +7.4298
(R2 = 0.9956)

Y = -0.249 x +7.6253
(R2 = 0.9693)

Y = -0.0051 x +6.6113
(R2 = 0.7646)

Y = -0.0267 x +6.5972
(R2 = 0.8597)


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