Adsorption properties of fly ash towards bivalent metal ions

The experiments were performed to evaluate the use of coal fly ash particles as an adsorbent for bivalent metal ions.The results show that coal fly ash is very effective for the adsorption of heavy metal ions in aqueous solutions.Adsorption of heavy metals is favorable in the order PbCuCdZn.With increasing pH,the removal percent of metal ions increase.Adsorption equilibrium is achieved in about 60 min.The isotherm adsorption data correspond with the Freundlich model well.However,the adsorption isotherm data appear as one linear region at pH=4.5 and two distinct linear regions at pH=6 and pH=8.When various heavy metals coexist,the adsorption of a particular heavy metal ion is influenced significantly by other ions.It is exhibited significant synergistic effect between Cd and Pb during adsorption process.The results of the tests using real wastewater reveal that fly ash is effective in the simultaneous removal of various heavy metals in metal industrial wastewater.