Research progress on synthesis of zeolites from coal fly ash and environmental applications

The by-product of coal combustion, coal fly ash (CFA), has become one of the world’s most emitted solid wastes, and bulk utilization while achieving high value-added products is the focus of current research. Using CFA to prepare zeolite cannot only reduce environmental pressure, but also obtain high value-added products, which has a good market prospect. In this paper, the research progress of hydrothermal synthesis method of CFA zeolites is reviewed in detail and summarized several other synthetic methods of CFA zeolites. This review also presents an overview of CFA zeolites application in environmental applications like water treatment, gas adsorption and soil remediation. However, a considerable number of literature data have documented using CFA zeolites for water treatment, whereas research on CFA zeolites application to gas adsorption and soil remediation is still limited. In addition, the current status of basic research on the industrial production of CFA zeolites is briefly summarized, and the development trend of the synthetic zeolite of CFA is prospected. After the feasibility analysis of the industrial production of CFA zeolite, it is concluded that the only two methods with high feasibility for industrial application are two-step hydrothermal and alkali melting methods, and the industrial production technology still needs to be studied in depth.[Figure not available: see fulltext.]