Preparation of activated carbon–zeolite composite materials from coal fly ash

Composite materials consisting of activated carbon and zeolites, which are expected to be suitable for environmental applications, were successfully prepared using coal fly ash with unburned carbon of ca. 8.0 mass% as a source material. The main components (SiO2 and Al2O3) along with unburned carbon were activated by NaOH fusion treatment at 750 °C in a N2 atmosphere, and subsequently converted into zeolites Na–X and/or Na–A with good crystallinity by hydrothermal treatment. The type of zeolite phase formed was dependent on the hydrothermal treatment conditions including NaOH concentration. In this report, the influence of preparation parameters and the presence or absence of unburned carbon on the chemical conversion of coal fly ash into composite materials consisting of activated carbon and zeolites is described.