Résumé
The sonocatalytic degradation of EDTA and Rhodamine B (RhB) was studied under 345 kHz (Pac = 0.25 W mL-1) ultrasound (US) at 40 °C under Ar/20%O2, Ar and air in the presence of metallic titanium (Ti0) and core-shell Ti@TiO2 nanoparticles (NPs). Ti@TiO2 nanoparticles have been obtained by sonohydrothermal treatment (20 kHz, 19 bar, 200 °C) of commercially available Ti0 nanoparticles in pure water. The obtained material is composed of quasi-spherical Ti0 particles (30-150 nm) coated by 10-20 nm crystals of defect-free anatase1,2. It was found out, that the combination of 345 kHz US with the metallic Ti0 NPs enhances the degradation of EDTA (C0 = 5 10-3 M) under Ar20%O2 atmosphere. The suggested mechanism of EDTA sonocatalytic degradation involves sonochemical oxidation of EDTA molecule by OH∙/HO2∙ radicals in solution and EDTA oxidation at the surface of Ti0 NPs in the presence of O2 activated by the cavitation event3. On the other hand, RhB sonochemical degradation with 345 kHz US is efficient even without catalyst. As shown in Table 1, the addition of metallic Ti0 and core shell Ti@TiO2 NPs doesn’t enhance the degradation of RhB molecules as in the case of EDTA. Thus, the mechanism of RhB degradation by power US is controlled by the in situ generated chemically active species OH∙, OH2∙ and O2∙.