Adsorption Equilibrium for Heavy Metal Divalent Ions (Cu²⁺, Zn²⁺, and Cd²⁺) into Zirconium-Based Ferromagnetic Sorbent

Table 3

The comparison between correlation coefficient, , and average relative error (ARE) among seven two-parameter isotherm models.

Isotherm models	Cu^2+		Zn^2+		Cd^2+
		ARE (%)		ARE (%)		ARE (%)
Langmuir	0.7282	1.92	0.7130	4.96	0.8550	2.65
Freundlich	0.8592	3.20	0.9136	1.59	0.8779	0.56
Dubinin-Radushkevich	0.6952	4.90	0.3759	4.81	0.8037	4.03
Temkin	0.6640	3.23	0.7624	1.89	0.9024	1.44