Résumé
Ultrasound is more and more used in many fields and in particular for the synthesis of nanomaterials. But for the moment only few stbeen conducted to understand the processes involved during the synthesis of nanomaterials in hydrothermal water under ultrasound, hence the novelty of the subject of study. We are interested in the synthesis of zeolite A and its conversion into sodalite under simultaneous action of hydrothermal conditions and 20 kHz ultrasound (SHT). To determine the impact of ultrasound on the kinetics of conversion of zeolite A into sodalite, different experiments were conducted starting from dissolved silica and sodium aluminate. First, the syntheses were carried out in conventional autoclave at 150 °C during 12 hours only conditions under which sodalite forms. Other syntheses were performed in the SHT reactor at 100°C for 30 minutes After studying the impact of synthesis time and synthesis temperature on the conversion of LTA to sodalite in the SHT reactor and in hydrothermal synthesis, we investigated the influence of other parameters in the conversion of LTA into sodalite, such as the viscosity of the medium and the ratio Si/Na and Si/Al, the density and sound power absorbed in the reactor in the SHT reactor, the pressure in the Parr bomb reactor. After a precipitation under silent conditions, the samples were processed at 100 °C from 1 hour to 3 hours in the SHT reactor and 12 h at 150°C in the HT reactor respectively. The characterization of the products by scanning electron microscopy and by powder XRD revealed the impact of SHT treatment on the size and morphology of the crystalline products and also on the conversion kinetics of the amorphous gel into LTA and sodalite.