STUDY OF STRUCTURAL TRANSFORMATIONS IN POTASSIUM-EXCHANGED ZEOLITE-A INDUCED BY THERMAL AND MECHANOCHEMICAL TREATMENTS

Thermal transformations of potassium-exchanged zeolite A and the X-ray amorphous material obtained by ball milling the potassium-exchanged z eolite A were investigated by different methods, such as differential thermogravimetric analysis (DTA), differential scanning calorimetry (D SC), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spe ctroscopy. Controlled heating of crystalline, potassium-exchanged zeol ite A causes a phase transformation in the sequence: [0.22 Na2O, 0.78 K2O]. Al2O3 . 2SiO(2) . 3.48 H2O double right arrow amorphous double r ight arrow kalsilite + kaliophilite, while the heating of mechanochemi cally amorphous potassium-exchanged zeolite A results in its transform ation into a mixture of kalsilite and kaliophilite. The differences in the pathways of the transformation processes are discussed in terms o f the structural properties of the starting materials.