Table 3.

Correlation coefficient ($R^2$) of the kinetic models performed.

Ions	Pseudo first order	Pseudo second order	Elovich model	Intraparticle diffusion
$P{b}^{2+}$	0.91	0.37	0.83	0.91
$C{d}^{2+}$	0.61	0.99	0.97	0.89
$C{o}^{2+}$	0.73	0.98	0.85	0.89
$C{u}^{2+}$	0.99	0.91	0.96	0.97
$H{g}^{2+}$	0.88	0.96	0.86	0.93
$N{i}^{2+}$	0.98	0.98	0.84	0.89
$Z{n}^{2+}$	0.74	0.87	0.76	0.95
$C{r}^{3+}$	0.88	0.99	0.41	0.84
$C{r}_2{O}_7^{2-}$	0.99	0.26	0.99	0.99

The numbers in bold correspond with the best adjustment to the studied models.