화학공학소재연구정보센터
Journal of Hazardous Materials, Vol.88, No.1, 107-121, 2001
Highly crystalline zeolite - a from flyash of bituminous and lignite coal combustion
Flyash is being generated in voluminous amounts by large scale coal combustion process. It poses a serious threat to thermal power industries specifically, in India, wherein the percent of utilisation of flyash is very poor (3-5%). In view of this problem, newer methods of its disposal and utilisation are being explored. The synthesis of zeolite from flyash appears to be one of the most promising alternatives as it has emphasis on value addition to waste material. Flyashes originating from different sources of coal differ in their characteristics and have implications in this work on Zeolite-A production. These factors have been thoroughly investigated and the conditions favourable for formation of Zeolite-A have been delineated. The reactivity of flyash towards zeolite formation is directly dependent on the SiO2/Al2O3 ratio, Fe2O3 and CaO content. Amongst the flyashes investigated, so far the sub-bituminous coal based flyash with SiO2/Al2O3 ratio of 3.47 appears to be a suitable substrate for Zeolite-A synthesis. These zeolites have been characterised with respect to XRD crystallinity, calcium binding capacity (CBC) and sorption capacity, wherein the crystallinity ranges from 50 to 100%, the CBC ranges from 290 to 560 meq/100 g and sorption capacity ranges from 16.6 to 23.8%.