In situ synthesis of low silica X zeolite on ceramic honeycombs for adsorption of heavy metals

In this study, a two-step method involving low-temperature aging and high-temperature crystallization was employed for the first time in the in situ hydrothermal synthesis of low silica X (LSX) zeolite on a ceramic honeycomb. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and Fourier transform-infrared spectroscopy. The LSX-zeolite-ceramic composites exhibited uniform morphology and had a low silica-to-alumina (Si/Al) ratio of 1.05. The samples were crystallized twice in situ by hydrothermal treatment and the resulting composites exhibited excellent uptake of the heavy metal ion, Cd2+, from aqueous solution. Moreover, the composite material could be reused several times after regeneration, and after five cycles, the removal rate of heavy metal ions was still as high as 99 %.