ChemInform Abstract: A Review on Synthesis, Characterization and Industrial Applications of Flyash Zeolites

Flyash, an industrial by-product, rich in silica an d alumina contents, has been known to be a useful material for synthesizing zeolites. These zeolites are minerals of alumino silicate group and exhibit high affinity to accommodate and exchange one or a group of metallic cations and/or water molecules. Though, zeolites find several industrial applications of high commercial and environmental values, their synthesis, characteriza tion and recommendations for the most appropriate application are challenging tasks. This is mainly due to the fact that ash zeolites can be synthesized by employing different synthesis methods (viz., hydrothermal, fusion, microwave assisted hydrothermal and molten salt method) and s everal factors (viz., concentration of alkali source, temperature, time of reaction, liquid/solid ratio and type of flyash), which can significantly affect their overall properties. As such, a critica l review of these methods and their limitations and superiority over each other becomes necessary. Inci dentally, it has also been demonstrated by the researchers that there are several industrial appli cations for these fly ash zeolites and selection of a particular type of the zeolite would depend on its basic properties (viz., pore volume, crystal structure, Si/Al ratio and ion exchange characteris tics). Hence, review of various industrial applications of zeolites and a critical commentary on the methodologies employed for zeolite selection also becomes important. As such, efforts have been made in this paper to address these issues in detail.