首页|Sonocatalytic degradation of EDTA in the presence of Ti and Ti@TiO2 nanoparticles
Sonocatalytic degradation of EDTA in the presence of Ti and Ti@TiO2 nanoparticles
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NSTL
Elsevier
The sonocatalytic degradation of EDTA (C-0 = 5 10(-3) M) in aqueous solutions was studied under 345 kHz (P-ac = 0.25 W mL(-1)) ultrasound at 22-51 degrees C, Ar/20%O-2, Ar or air, and in the presence of metallic titanium (Ti-0) or core-shell Ti@TiO2 nanoparticles (NPs). Ti@TiO2 NPs have been obtained using simultaneous action of hydrothermal conditions (100-214 degrees C, autogenic pressure P = 1.0-19.0 bar) and 20 kHz ultrasound, called sonohydrothermal (SHT) treatment, on Ti-0 NPs in pure water. Ti-0 is composed of quasi-spherical particles (30-150 nm) of metallic titanium coated with a metastable titanium suboxide Ti3O. SHT treatment at 150-214 degrees C leads to the oxidation of Ti3O and partial oxidation of Ti-0 and formation of nanocrystalline shell (10-20 nm) composed of TiO2 anatase. It was found that Ti-0 NPs do not exhibit catalytic activity in the absence of ultrasound. Moreover, Ti-0 NPs remain inactive under ultrasound in the absence of oxygen. However, significant acceleration of EDTA degradation was achieved during sonication in the presence of Ti-0 NPs and Ar/ 20%O-2 gas mixture. Coating of Ti-0 with TiO2 nanocrystalline shell reduces sonocatalytic activity. Pristine TiO2 anatase nanoparticles do not show a sonocatalytic activity in studied system. Suggested mechanism of EDTA sonocatalytic degradation involves two reaction pathways: (i) sonochemical oxidation of EDTA by OH center dot/HO2 center dot radicals in solution and (ii) EDTA oxidation at the surface of Ti-0 NPs in the presence of oxygen activated by cavitation event. Ultrasonic activation most probably occurs due to the local heating of Ti-0/O-2 species at cavitation bubble/solution interface.
NSTL
Elsevier
