Synthesis, characterization, and application of sol gel derived Mg2SiO4 powder

Abstract

This paper reports a successful preparation of a pure forsterite Mg2SiO4 using the sol–gel approach and its application for the removal of impurities from a Tunisian frying oil. Magnesium nitrate hexahydrate and tetraethylortho-silicate were used as magnesium and silicon precursors, respectively. The synthesis was held at different calcination temperatures for 30 min. The annealed samples were characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, and laser diffraction. The results revealed that the sample calcined at 500 °C was forsterite with unimodal particle size distribution (PSD) centered at 122.8 ± 0.3 μm. The dispersion index I (indicator of particle size uniformity) was 1.84. With the temperature increase, well crystallized compounds were obtained. Their PSDs remain unimodal and shift towards smaller particles. A decrease of the dispersion index was also noted, indicating the formation of Mg2SiO4 with more uniform particle size. This study showed that 900 °C could be selected as energy saving temperature suitable for the preparation of a pure and well crystallized Mg2SiO4 within just 30 min of annealing time. The obtained silicate exhibited promoting results for the purification of waste frying oils.