| Excessive iron（Fe） and manganese（Mn） in water can threaten the growth of organisms. As a waste material of thermal power plants, fly ash has a good performance to adsorb Fe and Mn by complexation, ion exchange and bonding from aqueous solutions. Batch adsorption experiments were performed under isothermal conditions（25±1）℃, in order to evaluate the effect of various parameters which include oscillation time, dosage of modified fly ash, initial concentration of Fe and Mn on the efficiency of removal using modified fly ash by alkali. The results showed that the modified fly ash had higher removal capacity than raw fly ash. The highest Fe（Ⅲ） and Mn（Ⅱ） removal occurred at 8h with the optimal dosage of 10 g·L-1, and the maximum adsorption capacity reached at 4.8 and 0.81 mg·g-1, respectively. The removal rate of Fe（Ⅲ） showed increasing trend with increasing initial concentration, then it reached equilibrium. While removal rate of Mn（Ⅱ） remained at high level（>80%） with low initial concentration（<8 mg·L-1） and then decreased sharply with the increase of initial concentration. Kinetic studies indicated that Mn（Ⅱ） in binary-ion system was more in accordance with pseudo second-order kinetic model but Fe（Ⅲ） had no suitable adsorption kinetic pattern to follow. Accordingly, modified fly ash will play a significant role in removal of Fe and Mn from aqueous solution in the future. |
