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A NOVEL AND GREEN APPROACH OF SYNTHESIS AND CHARACTERIZATION OF NANO-ADSORBENTS (ZEOLITES) FROM COAL FLY ASH: A REVIEW

Y. P. CHAUHAN and MOHD. TALIB

Coal fly ash (CFA) is the waste product of combustion of coal in a coal-fired power station. The global annual production of CFA is about 800 million tons and this amount is predicted to increase in the future. However, the global recycling rate of CFA is only 15% posing important challenges in waste management. In India, more than 120 million tons of fly ash is being generated annually with more than 65,000 acres of land being occupied by ash ponds. Several approaches have been made for proper utilization of fly ash, either to reduce the cost of disposal or to minimize the environmental impact. One of the approaches is the conversion of fly ash to zeolites, which have wide applications in ion exchange, as molecular sieves, catalysts and adsorbents. Zeolites have extensive applications in basic science, petrochemical science, energy conservation/storage, medicine, chemical sensor, air purification, environmentally benign composite structure and waste remediation. However, the uses of zeolites in these areas, especially environmental remediation, are restricted due to prohibitive production cost. Efficient recycling and resource recovery from coal fly ash has been a major topic of current international research interest, aimed at achieving sustainable development of human society from the view points of energy, economy and environmental strategy. For zeolite, this novel production method allows a reduction by half of the total production time while maintaining a high degree of crystallinity of zeolite which exists in a narrower particle size distribution.