PREPARATION OF ZEOLITE FROM COAL FLY ASH AND ITS ADSORPTION-DESORPTION BEHAVIOR ON AMMONIUM ION IN AQUEOUS SOLUTION

Owing to the high content of SiO2 and Al2O3, fly ash utilization as starting material for zeolite is becoming a great interest. In this research, fly ash was converted into zeolite using reflux method at 138 degrees C for 1 hour in NaOH 2M followed by heat treatment at 90 degrees C for 24 hours. The characterization of the resulting zeolite was carried out using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET surface area measurement. The study of its adsorption-desorption behaviors were also investigated using ammonium solution. Infrared spectra showed typical zeolite peaks for Si-O-Si or Al-O-Al stretching at 985 cm(-1), Al-O-Si stretching at 663 cm(-1), and Al-O or Si-O bending at 455 cm(-1). XRD analysis confirmed the formation of sodium aluminium silicate hydrate, which is a sodalite zeolite. The surface areas of coal fly ash and zeolite were 6.9 m(2)/g to 34.1 m(2)/g, respectively. The ZFA was able to adsorb 2.9 mg/g ammonium ions upon 135 minutes of adsorption time. During the desorption experiment, a slow release of only 0.3 mg of NH4+ was observed out of 250 mg of NH4+ adsorbed upon 24 hours of desorption time.