An improved process for the production of flyash based sodalite

Flyash based sodalite (FAS) having silica to alumina molar ratio of 0.9 - 1.5 is prepared from a reaction mixture of flyash and caustic soda. The reaction mixture has specified properties of Na2O, SiO2, AI2O3 and H2O. A caustic soda to flyash ratio greater than 1.2 yields exclusively sodalite product at fusion temperature of 550 - 600°C and crystallisation time of 4-10 hrs. Morphological characterisation using scanning electron microscopy reveals cubic structure as corroborated with XRD data. The exchange capacity (340-360 meq/100 g) and surface area compare well with that reported in literature. The surface area and exchange capacity indicates their uses as a low-cost ion exchanger, water softener and conditioner etc.