Low-Cost Fau-Type Zeolite X Synthesis from Silica Fume and Aluminum Foil Waste

Abstract

Introduction: Zeolites are a group of crystalline microporous aluminosilicates with exceptional properties that enable their use in various fields. Although zeolites are commonly found in nature, impurities in them can limit their applications. Therefore, synthetic zeolites are usually favored, as their properties can be tailored to specific applications by adjusting the synthesis conditions, e.g., Si/ Al ratio, synthesis temperature, time and the order of adding the reactants. By such control, zeolites with different topologies (SOD, FAU, GIS, LTA, etc.) and properties can be obtained.

 Aim: To develop a sustainable and cost-effective synthesis of zeolite X (FAU type) using waste materials as raw sources, with optimization of the synthesis conditions to obtain a product suitable for further application.

 Materials and Methods: Zeolite X was synthesized using waste microsilica as the silicon source and waste aluminum foil as the aluminum source. Prior to gel preparation, the precursors were dissolved in NaOH solution, after which the solutions were combined and left to stir. After a certain amount of time, the prepared gel was transferred into a plastic bottle. To obtain the desired FAU zeolite, a seeding approach was employed to induce crystallization and crystal growth. After adding seeds of commercial Zeolite 13X to the gel in the bottle, the bottle was placed in an oven at 100 °C for 16 h or 24 h. The resulting solids were washed, filtered, and oven-dried at 100 °C for 1 h. 

Results: The powder X-ray diffraction (XRD) analysis revealed the desired FAU phase, with some additional peaks of the GIS phase and a minor amorphous component, depending on the crystallization time. 

Conclusion: These results demonstrate a successful utilization of waste materials as raw sources for zeolite synthesis, contributing to the circular economy and sustainable practices. Further work will focus on optimization of the synthesis procedure and application of the zeolite in different fields.