Synthesis, deposition and characterization of magnesium hydroxide nanostructures on zeolite 4A

The precipitation and self-assembly of magnesium hydroxide Mg(OH)2 nanopetals on dispersed zeolite 4A particles was investigated. Mg(OH)2/zeolite nanocomposites were produced from magnesium chloride solutions and characterized via X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared analysis (FTIR), and solid state NMR. It was determined that Mg(OH)2 interacted with bridging hydroxyl protons (SiOHAl) on the zeolite surface, but not with silanol or aluminol groups. NMR analysis showed that 13% of the tetrahedral Al sites on the zeolite were converted to octahedral Al. The zeolite structure and crystallinity remained intact after treatment, and no dealumination reactions were detected. This suggests that the deposition–precipitation process at ambient conditions is a facile method for controlling Mg(OH)2 nanostructures on zeolites.