Synthesis of Zeolites from Coal Fly Ash for the Removal of Harmful Gaseous Pollutants: A Review

SO_x, NO_x, CO_x, volatile organic compounds (VOCs), and Hg vapor directly and indirectly harm the atmospheric environment and human health by contributing to the formation of photochemical smog, acid rain, and haze and posing risks of potential toxicity (e.g., carcinogenicity). Therefore, effectively controlling and reducing the pollution caused by these chemicals is critical, and to that end, several methods have been developed, among which adsorption is one of the most common and effective techniques. As adsorption materials, zeolites show great potential in reducing air pollution. Moreover, coal fly ash (CFA)-based zeolite synthesis enables the simultaneous treatment of air and solid waste pollution. In this study, the progress of recent years in research on zeolite synthesis by CFA is reviewed, and the challenges besetting this method are discussed. In addition, we examine the application of CFA-based zeolites in removing or minimizing harmful gases. As we enter an era of utilizing disposed waste, developing efficient and low-cost materials for the removal of harmful gases may require improving the synthesis of high-purity, high-performance fly ash zeolite materials.