CATION EXCHANGE MECHANISM OF DIVALENT METALS IONS IN SYNTHETIC NaX AND LTA ZEOLITES: EFFICIENCY AND SELECTIVITY
In this investigation, the removal of divalent heavy metals by two types of zeolites has been studied. The mechanism of cation exchange for Cu2+, Ni2+, Cd2+ and Pb2+ on NaX Faujasite and Linde type A (LTA) zeolites was studied. Both zeolites are very efficient in divalent heavy metals removal from water. Ion exchange isotherms were performed and the thermodynamic parameters were calculated as well. Kielland plots showed that the order of selectivity is not the same for both the zeolites. For NaX it followed the following order Pb2+ > Cu2+ > Cd2+ > Ni2+ while for LTA the order is Pb2+ > Cd2+ > Cu2+ > Ni2+. Exchange velocity (kw) and the radii of the hydrated metals ions are involved in determining this order of selectivity.