Mobility of trace elements in fly ash and in zeolitised coal fly ash

• Influence of fly ash zeolitisation on the mobility of trace elements.
• Leaching tests were performed on fly ash and zeolitic fly ash synthesised from the fly ash.
• Low solubility is characteristic of most elements in both fly ash and zeolitic fly ash.
• The mobility of the elements investigated is lower in zeolitic fly ash samples than in fly ashes.
• Zeolitic fly ash is less dangerous than fly ash to environment and to human health.

To investigate for the influence of zeolitisation on the mobility of trace elements (As, Cd, Co, Cr, Cs, Cu, Mn, Ni, Pb, Se, V, and Zn) from coal fly ash, two samples of fly ash (FA and FB) were submitted to leaching tests as well zeolitic fly ash (ZFA and ZFB) that was synthesised from FA and FB. The leaching solutions were selected to represent the broad pH range of fluids in nature and landfills. The data indicate that a generally low solubility characterize the trace elements in both fly ash and zeolitic fly ash. However, the mobility of the elements investigated is lower in the ZFA and ZFB samples. This low mobility implies that the synthesis of zeolites, performed at low incubation temperature to keep low the cost of the experimental procedure, represents a useful method to solve environmental problems due to the disposal of the increasing production of fly ash. In addition, the final synthetic product is less dangerous for the environment and human health and can be used in different application because of the properties of the newly formed zeolites.