Low Temperature Sintering of Porous Zeolite Spheres via Waste Glass Powder Addition

Abstract

In this study, porous zeolite spheres were produced at a low temperature by a facile and economical method, sol-gel, using a natural zeolite from the Gördes region of Türkiye and waste soda glass powder. Waste glass powder was achieved by milling the recyclable waste soda glass bottles to be used as a source of silica. Elemental analysis of the waste glass was carried out by using X-ray fluorescence spectrometry. It was determined that Si (57.3 wt. %), Ca (20.9 wt. %), Na (13.9 wt. %), Mg (2.64 wt. %), and Al (1.64 wt. %) were the major constituents of the waste glass. Three different sphere compositions were designed containing 1:1, 3:2, and 7:3 zeolite:waste glass ratio. When the zeolite:waste glass ratio was 1:1 oval-shaped green spheres were achieved. For the compositions containing 3:2, and 7:3 zeolite:waste glass ratio spherical green samples were achieved. Prepared spheres were sintered at 300°, 400°, and 500°C for 1 h. It was observed that the samples could not maintain their spherical form when the sintering temperature was lower than 500°C. Scanning electron microscopy investigation of the spheres sintered at 500°C revealed that highly porous zeolite spheres, containing pores from ~20 µm to nanometre sizes, were achieved. Image J software was used to determine effect of composition on the size and size distribution of the sintered spheres.