Adsorption of Zn(II) in Aqueous Solutions by Kaolin

In this paper, adsorption performance of Zn(II) in simulative waste water by kaolin was studied, and the influences of solution initial pH value, temperature, adsorption time, concentration of Zn(II) were tested. Moreover, the thermodynamic parameters and kinetic equation were calculated. The results show that Zn(II) adsorption capacity firstly increases and then decreases as the pH increases, and the higher temperature, the better adsorption capacity. The Zn(II) adsorption occurs mainly within 60 minutes, and then leveling off. The calculations show that linear correlation coefficient (R2) of langmuir equation is better than the freundlich model fitting results, and Zn(II) adsorption can occur spontaneously, is an endothermic and entropy increasing process. In addition, first-order kinetic equation is more suitable for the description of Zn(II) adsorption mechanism, and adsorption activation energy equals 21.51 kJ•mol-1.