The thermal power plants, based on coals, are the main source of fly ash (FA). Depending on the type of source and the composition of the coal being burned, the components of the solid by-products could vary considerably, but all FA includes substantial amounts of silica (both amorphous and crystalline) and alumina, both of them being endemic ingredients in many coal-bearing rock strata. FA is a fine powder captured from flue gas streams by dust collecting systems prior to their release into the atmosphere FA is generally stored in landfills. The disposal of FA creates ecological risks because of the acidification and the infiltration of heavy metals and radioactive components into the soil. The production of zeolite from FA is result in a good ingredient of high value as additive to cement. An attempt to find a common solution for this environmental problem is reported in the present work.
It was successfully synthesized zeolite Analcime (ANA) from FA produced by combustion of coal in three termal power plants using a one-stage process - hydrothermal synthesis. Initial synthetic gels were obtained by preparing of mixture with ratio Sodium hydroxide/FA in the range of 2.0 to 1. By decreasing the amount of NaOH, crystallization of zeolites ANA, SOD, CAN and NaP begins. In order to obtain the mono-phase product zeolite Analcime, additional silica powder was added to the synthesis mixture. The obtained samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The adsorption capacity towards phenol of synthesized ANA-type zeolite samples were investigated for the purification of phenol-contaminated water.