Abstract
The adsorption characteristics of zeolites synthesized from fly ash were combined in a composite with the magnetic properties of iron oxides to produce adsorbents which were magnetic materials. Such zeolite/iron oxide magnetic composites were prepared with weight ratios of 3:1, 2:1 and 1:1. The experimental data for the equilibrium adsorption isotherms of Zn2+ ions onto the composites were modelled using the Freundlich and Langmuir equations. The presence of iron oxide had no significant effect on the adsorption capacities of the magnetic composites.
The experimental data were also employed to determine the kinetic characteristics of the adsorption process. The adsorption of Zn2+ ions was found to follow pseudo-second-order type kinetics. Although intra-particle diffusion occurred in the adsorption processes, it could not be accepted as the primary rate-determining step. The evaluated thermodynamic parameters indicated that the adsorption of Zn2+ ions onto zeolite/iron composites was spontaneous and endothermic.