Abstract
In order to prepare self-supporting faujasite (FAU) zeolite, a self-supporting zeolite block was synthesized in situ by hydrothermal treatment of a metakaolin base geopolymer. The effects of hydrothermal conditions such as hydrothermal alkalinity, temperature and time on the phase composition, microstructure and mechanical strength of the hydrothermal samples were investigated and evidenced by a series of characterization methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmet-Teller (BET). The results showed that a self-supporting faujasite block could be obtained by hydrothermal treatment of the geopolymer block in 2 M NaOH solution at 90 °C for 24 h, which had high crystallinity, regular morphology and high compressive strength. The self-supporting zeolite block had a compressive strength of 11.7 MPa, a pore volume of 0.24 cm3/g, and an average pore diameter of 7.86 nm. The specific surface area and the microporous specific surface area of the self-supporting faujasite blocks were 80.36 m2/g and 19.7 m2/g, respectively.
Highlights
Heavy metal pollution seriously harms the environment and human health [1,2,3]
The results showed that the geopolymer block could be hydrothermally treated in 2 M NaOH solution at 90 ◦ C for 24 h to obtain a self-supporting faujasite block with high crystallinity, regular morphology and high compressive strength
The self-supporting zeolite block had a compressive strength of 11.7 MPa, a pore volume of 0.24 cm3 /g, and an average pore diameter of 7.86 nm
Summary
Heavy metal pollution seriously harms the environment and human health [1,2,3]. How to effectively control heavy metal pollution is an urgent problem that needs to be solved. Zeolite has a three-dimensional skeleton and porous structure, and has strong adsorption capacity It is a widely used adsorbent material for removing such harmful pollutants [4]. NaA zeolite membrane with excellent pervaporation performance was prepared from geopolymer by hydrothermal method, and the evolution of zeolite-like structures was investigated. Synthesized self-supporting zeolite blocks containing Na-P1 zeolite and sodalite phase by hydrothermal treatment of fly ash-slag based geopolymer, the strength could reach 16.6 MPa, and confirmed that. Liguori et al [15] obtained a self-supporting zeolitic material with a hierarchical porosity by combining zeolite crystallization with a foaming process initiated by silicon and found that the silicon content, the relative humidity and curing time had great effect on the nucleation and growth of zeolite phases. X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmet-Teller (BET) adsorption and other characterization methods were used to investigate and evidence the impact of different hydrothermal conditions such as hydrothermal alkalinity, hydrothermal temperature and hydrothermal time on the formation and evolution of FAU crystals
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