Fig. 1.

Zinc and Cd adsorption isotherms in mono-metal and binary-metal systems. The solid lines represent best fits of adsorption data for Zn using the Freundlich model and for Cd using the Langmuir model. Experimental conditions: pH 6.5; 10 mmol L−1 NaNO3 background electrolyte; 1.0 g L−1 Al2O3 nanoparticles.

 


Fig. 2.

Effect of initial Zn and Cd concentration on separation factor, RL.

 


Fig. 3.

Zinc and Cd adsorption to Al2O3 nanoparticles at various concentrations of (A) phosphate (PO4), (B) citrate, and (C) humic acid (HA) in Zn mono-metal, Cd mono-metal, and binary-metal systems. Experimental conditions: 1 mmol L−1 Zn or Cd; pH 6.5; 10 mmol L−1 NaNO3 background electrolyte; 1 g L−1 Al2O3 nanoparticles.

 


Fig. 4.

Adsorption isotherms of (A) phosphate (PO4), (B) citrate, and (C) humic acid (HA) to Al2O3 nanoparticles in absence of metals, Zn mono-metal system, Cd mono-metal system, and binary-metal system. Experimental conditions: pH 6.5; 10 mmol L−1 NaNO3 background electrolyte; 1 g L−1 Al2O3 nanoparticles.

 


Fig. 5.

Effect of (A) initial phosphate and (B) initial citrate concentration on separation factor, RL, for adsorption in absence of metals, and in Cd mono-metal, Zn mono-metal, and binary-metal systems.