Precipitation and growth of magnesium hydroxide nanopetals on zeolite 4A surfaces

We have studied the precipitation and growth of magnesium hydroxide Mg(OH)2 nanopetals on zeolite 4A particles dispersed in aqueous magnesium chloride solutions at 298 K. We show that the precipitation of these petal-like nanostructures can be achieved by the addition of ammonium hydroxide to aqueous magnesium chloride, and their growth can be controlled by concentration and pH. We propose a mechanism for nanocomposite formation driven by acid–base interactions between the bridging hydroxyl groups on the zeolite surface and weakly basic Mg(OH)2.

► Mg(OH)2 nanopetals can be assembled on zeolite 4A by adding aqueous NH4OH to magnesium chloride solutions containing dispersed zeolite particles.
► Nucleation of Mg(OH)2 is driven by acid–base interactions between bridging hydroxyl groups on the surface and the weakly basic Mg(OH)2.
► The rate of precipitation of Mg(OH)2 nanostructures increases with increasing magnesium chloride concentration.
► Increasing synthesis time facilitates the growth of Mg(OH)2 crystals and leads to increasing Mg(OH)2 content in the nanocomposite.