Removal of Pb2+ from Aqueous Solutions Using K-Type Zeolite Synthesized from Coal Fly Ash

Abstract

In this study, a novel zeolite (K-type zeolite) was synthesized from coal fly ash (FA), and adsorption capacity on Pb2+ was assessed. Six types of zeolite (FA1, FA3, FA6, FA12, FA24, and FA48) were prepared, and their physicochemical properties, such as surface functional groups, cation exchange capacity, pHpzc, specific surface area, and pore volume, were evaluated. The quantity of Pb2+ adsorbed by the prepared zeolites followed the order FA < FA1 < FA3 < FA6 < FA12 < FA24 < FA48. Current results indicate that the level of Pb2+ adsorbed was strongly related to the surface characteristics of the adsorbent. Additionally, the correlation coefficient between the amounts of Pb2+ adsorbed and K+ released from FA48 was 0.958. Thus, ion exchange with K+ in the interlayer of FA48 is critical for the removal of Pb2+ from aqueous media. The new binding energies of Pb(4f) at 135 and 140 eV were detected after adsorption. Moreover, FA48 showed selectivity for Pb2+ adsorption in binary solution systems containing cations. The results revealed that FA48 could be useful for removing Pb2+ from aqueous media.