Synthesis optimization and characterization of a novel zeolite produced from coal fly ash by hydrothermal reaction in alkaline solution

Abstract

ABSTRACT A novel 4A zeolite was successfully synthesized through a green and facile hydrothermal method by using coal fly ash from the flue gas of a thermal power plant as the raw material. The synthesis process was investigated and optimized by single-factor and orthogonal experiments and response surface optimization. Results showed that the Ca2+ exchange capacity of the product reaches 310.2 mg/g under the liquid–solid ratio of 8:1, NaOH solution concentration of 2.41 mol/L, and reaction temperature and time of 95°C and 6 h. This capacity corresponds with the predicted value of the response surface. Characterization tests revealed that the product has good crystallinity and spherical cage morphology, and the specific surface area reaches 5.76 m2/g. All these findings indicated that the hydrothermal treatment of coal fly ash in alkaline solution to prepared zeolite is a feasible route that is environmentally friendly and efficient.