Assessment of hydrothermal parameters on alkaline activation of fly ashes using a central composite design


  • Ivan SUPELANO GARCÍA Pedagogical and Technological University of Colombia, GFM Group, North central avenue 39-115 Tunja, Boyacá 150001, Colombia
  • César Armando ORTÍZ OTÁLORA Pedagogical and Technological University of Colombia, GSEC Group, North central avenue 39-115 Tunja, Boyacá 150001, Colombia
  • Carlos Arturo PARRA VARGAS Pedagogical and Technological University of Colombia, GFM Group, North central avenue 39-115 Tunja, Boyacá 150001, Colombia
  • Julieth Alexandr MEJÍA GÓMEZ Antonio Nariño University, Faculty of science, GIFAM group, avenue 7 # 21-84, Tunja, Boyacá 150002, Colombia



coal fly ash, zeolitic materials, hydrothermal method, central composite design


Coal fly ash (CFA) is a powder generated during combustion of coal; its improper disposal constitutes an environmental issue. To minimize this problem, one of the uses of CFA is as feedstock for production of zeolite. Different studies have shown that zeolites may be easily obtained from CFA by relatively cheap and fast conversion processes. Most of these studies have been focused on the study of the zeolite synthesis using classical methods through changing one factor per time and fixing the other factors, where it illustrates the impact of each variable individually via a huge number of experiments, however it doesn’t consider the effect of the interaction between different factors under study.

This study aims to evaluate the effects of hydrothermal synthesis parameters, time of activation (t), temperature of synthesis (T) and concentration of alkaline activator ([NaOH]), on the formation of zeolite. Morphological and structural properties were determined through scanning electron microscopy and X-ray diffraction. The experiments were designed through a central composite design. The results revealed that 4M NaOH, 90℃ and time synthesis of 36 h were the conditions for a higher conversion of CFA into sodalite, furthermore, it was obtained P1-Na and losod as zeolite phases.


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How to Cite

I. SUPELANO GARCÍA, C. A. ORTÍZ OTÁLORA, C. A. PARRA VARGAS, and J. A. MEJÍA GÓMEZ, “Assessment of hydrothermal parameters on alkaline activation of fly ashes using a central composite design”, J Met Mater Miner, vol. 31, no. 2, pp. 54–61, Jun. 2021.



Original Research Articles