Highly crystalline zeolite — a from flyash of bituminous and lignite coal combustion

• Published in: Journal of hazardous materials Vol. 88; no. 1; pp. 107 - 121
• Main Authors: Rayalu, S.S, Udhoji, J.S, Munshi, K.N, Hasan, M.Z
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 16.11.2001; Elsevier
• Subjects: Applied sciences; Characterisation; Chemistry; Coal; Crystallization; Environmental Pollution - prevention & control; Exact sciences and technology; Flyash; General and physical chemistry; Incineration; Ion-exchange; Optimisation; Other industrial wastes. Sewage sludge; Pollution; Refuse Disposal - methods; Surface physical chemistry; Synthesis; Wastes; Zeolite-A; Zeolites - chemistry; Zeolites: preparations and properties; Synthesis; Characterisation; Zeolite-A; Optimisation; Flyash; Scanning electron microscopy; Subbituminous coal; Raw materials; Zeolite; Experimental study; X ray diffraction; Optimization; Molecular sieve; Characterization; Fly ash; Industrial waste; Lignite; Upgrading; Preparation; Waste reuse; Coal power plant; Solid waste; Test method; Lixiviation
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/S0304-3894(01)00296-5

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 SiO 2/Al 2O 3 ratio, Fe 2O 3 and CaO content. Amongst the flyashes investigated, so far the sub-bituminous coal based flyash with SiO 2/Al 2O 3 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%.