The adsorption behavior of Pb(II) and Cd(II) ions in aqueous solutions on silica aerogels modifi ed with amino propyl triethoxysilane was investigated as a function of pH, contact time, adsorbate concentration and adsorbent dose. It was found that maximum adsorption of Pb(II) and Cd(II) ions occurs at pH 6.0 and pH 8.0, respectively. The optimum contact time to obtain equilibrium adsorption with the modifi ed silica aerogel was experimentally found to be around 48h. Adsorption isotherms clearly indicated that the adsorption behavior of metals ions on the modifi ed silica aerogels is fi tted well with both the Langmuir and Freundlich isotherms. The maximum adsorption capacities of Pb(II) and Cd(II) on modifi ed silica aerogel were found to be 45.45mg/g and 35.71mg/g, respectively. The results indicated that silica aerogels modifi ed with amino functional groups can be used as an effi cient adsorbent in the removal of metal ions such as Pb(II) and Cd(II) from aqueous solutions.

A B S T R A C TThis study focused on the adsorption of copper (II) and nickel (II) from aqueous solutions onto silica aerogel modified with amino propyl triethoxysilane as a compound containing amino functional group. The batch experiments were conducted at various conditions including contact time, pH, adsorbent dose, and adsorbate content. The results showed that the equilibrium time occurred within 5 h for Ni(II) and 24 h for Cu(II) and the maximum adsorption capacity for both the ions happened at a pH of 6. The kinetic and isotherm adsorption of the modified silica aerogel fitted well to pseudo-second order model and Langmuir model, respectively. The Langmuir isotherm model results showed that the maximum adsorption capacity (Q m ) of the modified adsorbent was 47.6 mg/g for Cu(II) and 27.7 mg/g for Ni(II). Experimental data analysis by Dubinin-Radushkevich isotherm also illustrated that the metals adsorption onto the sorbent was physical in nature. With regard to the sorption capacity obtained by the modified silica aerogel, it can be considered as an efficient sorbent in the removal of the metal ions.