Abstract: Ethylenediamine-grafted silica gel(EDA/SiO2) with the amino content of 1.35 mmol/g was synthesized. Its adsorption capacities toward copper and zinc cations in both single-component and binary-component aqueous solutions were studied. The influences of the flow rate and initial concentration of metal cations in the solution on the adsorption time were quantitatively determined. The results showed that the adsorption time decreased dramatically with the increase of the initial concentration of copper cations as well as the flow rate of the solution. The removal of copper cations by EDA/SiO2 column could be evaluated by the Thomas model. The initial copper concentration exerted significant effect on the Thomas saturation adsorption capacities(q0), which were increased from 0.272 mmol/g to 0.476 mmol/g in the initial concentration range of 1.99 mmol/L to 10.00 mmol/L. But no significant influence of the solution flow rate could be observed. The model rate constant kTh increased when the initial concentration was decreased or the flow rate of solution increased. In single component solutions, the adsorption capacities of EDA/SiO2 toward Cu(Ⅱ) and Zn(Ⅱ) were 0.340 mmol/g and 0.127 mmol/g, respectively. However, such adsorption capacities decreased in binary-component solution. The adsorption of zinc cation was decreased in the presence of copper cations, suggesting that the removal of copper was superior to that of zinc cations from aqueous solution. Furthermore, EDA/SiO2 could be regenerated by hydrochloric acid solution and ammonia water, and its adsorption capacity could be maintained even after regeneration for 6 times.

Key words: ethylenediamine-grafted silica gel, Cu(II), Zn(II), dynamic adsorption