A study on removal characteristics of heavy metals from aqueous solution by fly ash.

The purpose of this study was to investigate the possibility of the utilization of coal fly ash as a low cost adsorbent. Batch experiments were conducted to evaluate the removal of heavy metals from aqueous solutions by fly ash under various conditions of metal concentration, pH and fly ash dosage. The heavy metals used in this study were zinc, lead, cadmium and copper. Adsorption studies were done at various pH values (3-10) at 25 degrees C and at heavy metal concentrations of 10-400 mg/L using fly ash concentrations of 10, 20 and 40 g/L, respectively. Experiments were also conducted without fly ash to determine the extent of heavy metal removal by precipitation. Kinetic experiments were also performed and the zeta-potentials of the fly ash particles were measured at various pH's. The adsorption data was described by the Freundlich adsorption model. The test results using real wastewater indicated that fly ash could be used as a cheap adsorbent for the removal of heavy metals in aqueous solutions if not strongly acidic.