Synthesis of zeolites by alkaline activation of ferro-aluminous fly ash

Abstract
Zeolites were synthesized from fly ash by alkaline hydrothermal activation. High-Fe fly ash from the Teruel power station in NE Spain was the starting material. The activation was performed by 0.1 M NaOH and KOH solution in a closed system. Zeolite formation was studied as a function of temperature (60 and 150°C), reaction time (24, 168 and 336 h) and sample/solution ratio (30, 60, 100 and 200 gl−1). The zeolitic products synthesized were phillipsite, merlinoite, analcime, zeolite Na-P1 and nosean. Other reaction products identified were portlandite and bayerite. The activated material in the fly ash was mainly glass and quartz. The highest zeolite synthesis efficiency was 75%.