Two-step method for preparation of NaA-X zeolite blend from fly ash for removal of cesium ions.

Pure zeolites can be synthesized from silica extracts obtained from fly ash by alkaline leaching. The extraction potential of industrial by-product fly ash was investigated under repeated fusion process conditions. The amount of extracted silica was 131.43 g/kg ash while the amount extracted alumina was limited to 41.72 g/kg ash. The results of zeolite synthesis from the Si-bearing extracts demonstrated that pure zeolites with high cation exchange capacity (4.624 meq/g) can be produced. The sorption potential of synthesized A-X zeolite blend for the removal of cesium ions has been investigated. The influences of pH, contact time and temperature have been reported. Thermodynamic parameters such as changes in Gibbs free energy (DeltaG degrees), enthalpy (DeltaH degrees) and entropy (DeltaS degrees) were calculated. A comparison of kinetic models applied to the sorption data was evaluated for pseudo first-order, pseudo second-order and homogeneous particle diffusion models. The results showed that both the pseudo second-order and the homogeneous particle diffusion models were found to best correlate the experimental rate data.