INFLUENCE OF NaOH CONCENTRATIONS DISSOLVED IN SEAWATER AND HYDROTHERMAL TEMPERATURES ON THE SYNTHESIS OF ARTIFICIAL ZEOLITE FROM COAL FLY ASH

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Conversion of waste coal fly ash, released mainly from thermal power plants, to artificial zeolite is important in view of environmental conservation and recycle of resources. To reduce cost for the artificial zeolite synthesis, we applied seawater instead of tap or distilled water for preparation of NaOH solution. The reaction products with NaOH concentrations of 1.0 and 2.0 M at 121 and 144℃ had cation exchange capacity (CEC) values from 230 to 286 cmol(+) kg^-1, and the CEC values increased with increasing NaOH concentration and temperature. The X-ray diffraction (XRD) analyses showed that zeolite component in the products was Na-Pl having similar structure to phyllipsite. The XRD patterns and CEC values of the products were almost the same with corresponding products with distilled water. When the temperature was raised to 178℃, CEC decreased and analcime was formed especially at higher NaOH concentrations. These results indicate that the seawater containing waste heat of turbine generator in thermal power plants can be used in synthesis of artificial zeolite, and that the use of the waste hot seawater will save heat energy and water cost in the artificial zeolite production.
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