Preparation of Coal Slag Based Zeolite Molecular Sieves and Their Adsorption Performance for Carbon Dioxide

Abstract

Anthropogenic carbon dioxide (CO₂) over-emission has been identified as a dominant driving factor for a series of global ecological problems, including global warming and sea level elevation. Accordingly, exploiting cost-effective and high-performance CO₂ adsorption materials has become a research topic with prominent practical application value. As a class of well-established high-efficiency adsorbents, zeolite molecular sieves have shown remarkable application prospects in the field of CO₂ capture. Nevertheless, traditional synthesis routes for zeolites generally suffer from drawbacks such as high raw material cost and cumbersome preparation procedures. To tackle the above limitations, this work selected bulk industrial solid waste coal slag as the primary feedstock. Sieving and acid leaching pretreatment procedures were implemented to effectively enrich the active silicon and aluminum components in the raw slag. With sodium hydroxide (NaOH) and sodium aluminate (NaAlO₂) as auxiliary reagents, sodalite (SOD) zeolite molecular sieves were successfully fabricated via an alkali fusion coupled with hydrothermal synthesis approach. The influences of varying synthesis parameters on the crystalline structure, microscopic morphology and CO₂ adsorption capacity of the as-synthesized zeolites were systematically explored. Experimental results confirm that the proposed route can realize the high-value resource conversion of solid waste, and the obtained zeolite molecular sieves possess satisfactory CO₂ adsorption performance. This study provides a novel technical strategy and reference for the development of low-cost and sustainable carbon capture materials.