Effect of Liquor/(Si/Al) Ratio on Zeolite Synthesis from Fumed Silica and Coal Fly Ash Using the Taguchi Approach

This study aims to evaluate the influence of a novel hydrothermal parameter, liquor/(Si/Al) ratio, on the crystallization of zeolite from fumed silica and fly ash by applying the Taguchi methodology. Template concentration, duration treatment, and crystallization temperature were adjusted to improve zeolitization yield. The resulting products were analyzed by XRD, FTIR, SEM–EDX, Raman microscopy, and nitrogen desorption–desorption experiments. The interaction of liquor/(Si/Al) parameters with considered factors was investigated by using ANOM and ANOVA analysis. The zeolitization content was considered as the measured response. The result indicated that a lower L/(Si/Al) ratio, with a contribution process of 20.42%, promoted a high zeolitization yield, while a higher L/(Si/Al) ratio involved a low zeolitization rate of starting materials. The medium temperature (120 °C), high NaOH concentration (2 M), medium treatment period (24 h), and lower L/(Si/Al) ratio (40) were shown to be the optimal conditions for maximum zeolitization yield. The zeolitization yield of started reactants reached 92.84% and Na-P1, Na-X, Na-Y, and analcime zeolites were the neoformed phases with a medium granulite area of 0.730 µm2 and surface area of 64.55 m2/g. Thus, the results demonstrate that carefully selecting operational factors may significantly influence zeolite synthesis.