The influence of separately and combined bentonite and kaolinite as binders for pelletization of NaA zeolite from coal fly ash

Abstract

Pelletization of zeolitic materials is required to facilitate their practical industrial and commercial applications. Zeolite-NaA was synthesized from fly ash by the fusion method and shaped into spherical granules. Bentonite, kaolinite, and a combination of bentonite with kaolinite were tested as binders with different contents from 5 to 10 wt%. The pellet formation was optimized. The physicochemical properties of binders, zeolite powder, and zeolite granular were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption/desorption isotherm, and scanning electron microscopy (SEM) among other techniques. Deformation and breakage behavior of spherical granulates by compression was also studied. The best performance was obtained by the pellet with 10% bentonite with satisfactory mechanical strength and water resistance. The XRD and SEM results revealed NaA zeolite granular with a typical cubic shape and high crystallinity formed on the surface of bentonite. This result presents a potential use of the coal fly ash to obtain pelletized NaA zeolite following the principles of circular economy and the sustainable development goals (SDGs), particularly SDG 12.

Keywords:
fly ash; zeolite; NaA; pelletization