Emulsion-derived urchin-shaped hydroxy sodalite particles

Urchin-shaped hydroxy sodalite (HS) particles composed of numerous nanorods of 400-500 nm in length with hexagonal cross-section of 50-100 nm in diameter were synthesized following non-ionic surfactant-stabilized water-in-oil (w/o) emulsions at a considerably low temperature of 90⁰C with a short duration, 10 h. The non-ionic surfactant, i.e. sorbitan monooleate (Span 80) of hydrophilic-lipophilic balance (HLB) value of 4.3 was found to be suitable for the preparation of emulsions. Crystalline phases and microstructures of the synthesized particles were studied by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) respectively. A relatively lower synthesis temperature (80 °C), under the same reaction conditions, resulted in the formation of thread-ball-like particles of HS along with a little amount of cubic NaA zeolite particles while flower-like HS particles were obtained at 100 °C. A tentative mechanism for the formation of HS particles of different morphologies was proposed. The HS particles find important use as seed crystals for the preparation of ceramic membranes in the separation technology and catalysis in various reactions.