Conversion of high silicon fly ash to Na-P1 zeolite: Alkaline fusion followed by hydrothermal crystallization

Abstract

In this research, we converted high silicon fly ash to a high ion-exchange capacity zeolite using a two stages conversion process. Alkaline fusion was applied to collapse the fly ash crystalline phases and release Si content. Then Si/Al ratio of the synthesis sol adjusted with appropriate amount of industrial grade materials. A synthesis solution with the molar ratio of 2.2 SiO 2:Al 2O 3:5.28 Na 2O:106 H 2O was hydrothermally crystallized to Na-P1 zeolite at 120 °C for 4 h. The as-synthesized zeolite characterized by means of X-ray diffraction, infrared spectroscopy, scanning electron microscopy and thermal analysis. Cation exchange capacity of the zeolite was determined using ammonium acetate method. The zeolitization remarkably improved the cation exchange capacity of the final product (e.g. 3.23 meq/g in comparison to the raw fly ash ∼0.005–0.02 meq/g). Due to the high CEC and sufficient whiteness of the final product, we suggest that the as-synthesized zeolitic powder is a potential candidate as a detergent builder.