Synthesis and Characterization of Zeolite-x From Coal Fly Ash Obtained From Thermal Power Plant of Gujarat State: a Parametric Optimization Approach

Abstract

Abstract The coal fly ash (CFA) is generally referred as waste generated. The authors tried to convert the waste into the useful product like Zeolite. The coal fly ash (Class-F) was used to synthesize Zeolite-X that was obtained from Mundra thermal power plant, Gujarat, India. In this present work, an alkaline fusion hydrothermal treatment method with and without seeding of sodium aluminate was employed for the synthesis. The purpose of this study is to maximize zeolite-X crystallization that is derived CFA. In addition to this study, authors also optimized the hydrothermal parameters using the L9 orthogonal Taguchi methodology. The operational parameters examined are: fusion temperature, fusion time, liquid/solid (L/S) ratio and concentration of alkaline solution. The effect of the selected parameters on the crystallization of zeolite-X was investigated using analysis mean (ANOM) and variance (ANOVA) method. Fly ash is transformed into zeolite by alkaline treatment with NaOH solution with varying molarity from 1 M to 3 M at 90 °C. The XRF study of CFA reveals predominant composition of quartz (SiO2), mullite (Al2O3.SiO2) and small quantity of hematite and magnetite. The effect of various parameters such as alkaline solution concentration, fusion temperature, crystallization time and seeding on the synthesis of zeolite formation has been studied. The highly crystalline zeolite (ZT-5) was obtained at 0.3 M NaOH solution at fusion temperature 550 °C with 90 hours of crystallization time with seeding of NaAlO3. The XRD pattern of zeolite (ZT-5) exhibits sharp peaks from 20°- 40° contrary to the CFA graph. The SEM images depict the transformation in morphology of CFA from smooth spherical texture to highly crystalline lattice structure. FT-IR absorption band reports sharp stretch around 440 cm-1 and 460 cm-1 and weak bend at 660 cm-1 and 694 cm-1 represents the relative O-T-O deformation and the alteration in shape of the Al-O-H bonds.