Abstract:

Ethylenediamine-grafted silica gel materials(EDA/SiO2) for the adsorption of Zn2+ were prepared with the use of γ-chloropropyltrichlorosilane as coupling reagent and ethylenediamine as a surface-modifying reagent. The adsorption behavior of EDA/SiO2 for Zn2+ and the effects of pH in Zn2+ solution, initial concentration, adsorption temperature and time were studied. The experimental results show that the pH value of Zn2+ solution affected the adsorption capacity of EDA/SiO2 significantly, and the suitable pH range was pH 3.0~5.5 for the adsorption of Zn2+. The adsorption equilibrium data for Zn2+ could be fitted according to the Langmuir model. The results of the thermodynamic parameters of the adsorption of Zn2+ on EDA/SiO2 show that this adsorption is an endothermic spontaneous process and increasing temperature is conducive to the adsorption. An interpretation was given for this, adsorption behavior of Zn2+ on EDA/SiO2. Adsorption kinetic data could be fitted by the pseudo-second-order kinetic equation, and the fitting kinetic constants were related with the initial solution concentration.

Key words: ethylenediamine-grafted silica gel, adsorption, Zn2+