Effect of acid pre-treatment on zeolite synthesis from fly ash: preliminary data

Fly ash is a by-product of thermal power plants partly disposed of in landfills. It is composed of
minerals and amorphous substances, i.e., quartz, mullite, hematite and magnetite, unburned coal
particles and amorphous aluminosilicate. Zeolites are tectosilicates characterised by a threedimensional
network of tetrahedral units that form a system of interconnected pores. The substitution
of silicon with aluminium produces a net negative charge which is balanced by the presence of an
extra cation in the framework. Due to their structure and their excellent ion exchange and sorption
properties, zeolites are useful in a number of applications. Many literature data have documented fly
ash conversion into zeolite.
The purpose of this study was to investigate the effect of different parameters on properties of zeolite
formed from fly ash. With this aim, crystallization time (from 1 to 72 h), alkaline ratio (0.75 and
1.25), type of water (distilled water and seawater), and action of acid treatment were investigated. The
experiments were performed at 40, 60, 90 °C. The synthetic products were characterized by X-ray
diffraction (XRD), scanning electron microscope (SEM), X-ray fluorescence spectrometry(XRF),
Infrared spectroscopy (IR), and Brunauer- Emmett-Teller (BET) method.
The results cofirm that the investigated parameters have significant effects on the structural properties
of zeolite synthesised.
Keywords: Fly Ash; Acid Pre-Treatment; Zeolite Synthesis