Chiang Mai Journal of Science

     The synthesis of zeolite X from bituminous fly ash (BFA) from the BLCP power plant in Rayong province of Thailand was examined. The initial Si/Al molar ratio of BFA was approximately 2, as determined via X-ray fluorescence. A stock solution for the hydrothermal synthesis of zeolite X was prepared by extracting the Si and Al species from BFA using 3 M NaOH. The Si/Al molar ratio of the stock solution was 18.44. The Si/Al ratio, temperature, ageing time, and concentrations of NaOH and KOH were investigated during the synthesis of zeolite X. QXRD, SEM, and BET were used for the characterization of zeolite X. For the optimal sample conditions, the Si/Al molar ratio of the stock solution was adjusted to 3 using Na₂AlO₃ dissolved in a KOH solution, followed by ageing at room temperature for 24 h and after ageing, the hydrothermal synthesis was performed at 75 °C for 24 h; the sample prepared under these conditions contained the highest amount of crystalline zeolite X (98.7%), with a surface area of 527.59 m²/g.