Synthesis of pure Na-X and Na-P zeolite from acid-extracting residues of CFB fly ash by a single-step hydrothermal method

Abstract

Acid-extracting residue of circulating fluidized bed (CFB) fly ash is still underutilized leaving disposal problems. In fact, high silica content inside this material opens a possibility to become a potential zeolites precursor. In this study, fine particles of acid residues have been reused to prepare zeolite Na-X and Na-P with high purity and intensity. Acid residue was used to synthesize zeolite Na-X and Na-P using a single-step hydrothermal process. The effects of crystallization time, temperature and sodium hydroxide concentration on the end products were investigated. The results revealed that crystallization time and temperature determined whether or not zeolite Na-X or Na-P was formed. The zeolites were characterized in terms of their mineralogical composition, morphology, and fourier-transform infrared spectroscopy.