Synthesis of NaHS zeolite using microwave assisted alkali activation of coal fly ash: preparation, mechanism, application

ABSTRACT High value-added NaHS zeolite was prepared using the microwave-assisted alkali fusion hydrothermal method from industrial solid waste coal fly ash as raw material without adding silicon and aluminum sources. The effect of mass ratio of alkali to coal fly ash, crystallization temperature, and crystallization time on the preparation of NaHS zeolite was investigated. The NaHS zeolite was characterized using XRD, SEM, BET, and FT-IR. The experimental results showed that the NaHS zeolite with complete crystal structure could be synthesized at m(sodium hydroxide):m(coal fly ash) = 2:1, crystallization temperature of 140°C, and crystallization time of 48 h. The prepared HS zeolite had high purity, complete crystal structure, and uniform grain size (2 μm). The NaHS zeolite was beneficial for CO2 adsorption properties with 110.9 cm3/g at 25°C.