Sorption of phosphate from solid/liquid interface by fly ash

In this study, fly ash was used to remove phosphate from aqueous solutions. The influence of suspension pH (3, 8 and 11.5), temperature (20, 30 and 40 °C), agitation rate (150, 200 and 250 rpm) and fly ash dosage on phosphate removal was investigated by conducting a series of batch sorption experiments. In addition, the mechanisms of phosphate removal were explained on the basis of the results of X-ray spectroscopy. The maximum phosphate sorption capacity of the fly ash was defined as 71.87 (mg/g). In this study, phosphate removal efficiency in excess of 99% was obtained. As the result of this study, it was thought that the removal of phosphate from solid/liquid interface by fly ash predominantly took place by precipitation mechanism, ion exchange and weak physical interactions between the surface of sorbent and the metallic salts of phosphate.