Fig. 2

Pseudo first-order (a) and pseudo second-order (b) kinetic plots of Ni and Zn sorption on γ-Al₂O₃ from 0.8 mM initial metal concentration solution at pH 7.5. The orange circles and red circles denote Ni sorption from binary- and single-sorbate systems, respectively. The indigo circles and blue circles denote Zn sorption from binary- and single-sorbate systems, respectively. The kinetic sorption data used for models fitting were collected up to 6 h, before which the equilibrium was not reached