Zeolite GIS Polymorphs Derived from Clay Fraction > 2 µm: The Ability of Clay Fraction > 2 µm for Crystallization of High-Purity Na-P1 Zeolite

Both Si and Al in clay fraction > 2 µm (Cf > 2 µm) of natural bentonite, volclay, was utilized for fabrication of low-cost Zeolite, which can be used in large scale of industry. This study focuses on the fabrication of single-phase gismondine-Na type P Zeolite (GIS-NaP) from Cf > 2 µm by hydrothermal treatment. The Cf > 2 µm was activated via alkaline fusion at 750 °C in a ratio of 1: 1.2, Cf > 2 µm: NaOH. Pure crystalline GIS-NaP Zeolite was successfully produced in a single step through a hydrothermal activation of the supernatant at 150 °C, which result from a water treatment of the fusion-Na-Cf > 2 µm in a ratio of 1: 4, fusion-Na-Cf > 2 µm: H2O. The Cf > 2 µm was identified by X-Ray diffraction (XRD). The supernatant was analyzed via Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The synthetic products were characterized with XRD, scanning Electronic Microscopy (SEM), Energy Dispersive and Fourier Transform Infrared spectroscopy (EDS and FT-IR) methods. The 18 h were sufficient that a high ordering crystallinity P1 polymorph was formed under Si/Al ratio: 1.47. The Zeolite Na-P1 content is found to obviously increase with increasing hydrothermal time from 18 to 36 h, so that the climax of Na-P1 Zeolite crystallization is reached at 36 h, with Si/Al ratio: 1.34. The N2 adsorption indicates the mesoporous character of Na-P1 at the climax, with BET surface area and pore size of 41.76m 2 .g −1 and 8.2 nm, respectively. Additionally, the polymorph P2 with Si/Al ratio around 1.81 was spontaneously formed after 6 days of crystallization (interzeolitic transformation) from the same supernatant. These results provide an experimental basis for the use of the clay fraction > 2 µm for the synthesis of Zeolites P, which may be useful in the future. Graphical Abstract