Sonochemical decomposition of natural polyphenolic compound (condensed tannin)

Sonochemical treatment of grape condensed tannin was studied with the aim to destroy phenolic constituents, using ultrasonic frequency of 20 kHz in the presence and in the absence of hydrogen peroxide (H 2O 2), as an oxidative agent. Various pH, H 2O 2 concentration and temperature combinations were used in order to investigate the role of these parameters in the studied process. In order to estimate the effect of ultrasound, similar experiments were conducted in terms of pH, H 2O 2 concentration and temperature conditions, but without sonication. In all cases the presence of H 2O 2 was resulted in considerably higher removal of total phenolics (TP). It was observed that pH and temperature present also a significant effect on TP removal in the presence of H 2O 2, both with and without sonication. Under similar experimental conditions higher reaction rates, concerning TP removal, were obtained in the presence of ultrasonic irradiation, than in its absence.