Expanding the synthesis of Stöber spheres: towards the synthesis of nano-magnesium oxide and nano-zinc oxide

In order to synthesise Stöber spheres of different diameters, fixed amounts of ethanol, ammonia and water were used with varying amounts of tetraethyl orthosilicate. This simple method was further applied to the synthesis of nano-ZnO and nano-MgO from their respective precursors, zinc methoxide and magnesium ethoxide. The spherical nano-SiO2, nano-ZnO and nano-MgO synthesised in this way were characterised by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. Preliminary investigations found that nano-ZnO and nano-MgO showed good catalytic activity in the trans-esterification reaction that converts vegetable oil to biodiesel.