In order to treat aqueous effluents containing organic pollutants, several techniques can be considereddepending on the organic compound concentration. Sonochemistry appears to be a promising solutionto answer water remediation issue. In fact, when submitted into a liquid, ultrasound can induce thenucleation, growth, and violent collapse of vapor/gas filled bubbles. However, despite the extreme localconditions observed during acoustic cavitation, using ultrasound alone is efficient only at low concentration in organic pollutants. In the present study, 0.05 M oxalic acid degradation kinetics were followed at40°C under various conditions, in presence or not of Pt/TiO2 catalyst under silent conditions or ultrasoundat 20 and 360 kHz. Experiments were achieved under controlled atmosphere and comparison betweenargon, Ar/O2(20 vol% O2) and pure O2 conditions was performed. Oxidation rate increase of oxalic acidwas measured under Ar/O2 atmosphere in presence of Pt/TiO2 catalyst due to strong dispersion effectof both low and high ultrasonic frequency and formation of chemically active species by sonolysis. Highfrequency ultrasonic irradiation under Ar/O2 atmosphere gives the highest kinetic increase compared tosilent conditions with oxalic acid degradation rate around 13 μmol min-1 at 40°C with 2 g L-1 of 3 wt%Pt on P25 TiO2 catalyst.
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© 2014 Elsevier B.V.
- Oxalic acid