The effects of hydrogen peroxide on the sonochemical degradation of phenol and bisphenol A

This report describes the effects of H2O2 concentration (0.01, 0.1, 1, and 10 mM) on the sonochemical degradation of phenol and bisphenol A (BPA) using an ultrasonic source of 35 kHz and 0.08 W/mL. The concentration of the target pollutants (phenol or BPA), total organic carbon (TOC), and H2O2 were monitored for each input concentration of H2O2. The effects of H2O2 on the sonochemical degradation of phenol was more significant than that of BPA because phenol has a high solubility and low octanol-water partition coefficient (Kow) value and is subsequently very likely to remain in the aqueous phase, giving it a greater probability of reacting with H2O2. The removal of TOC was also enhanced by the addition of H2O2. Some intermediates of BPA have a high Kow value and subsequently have a greater probability of pyrolyzing by the high temperatures and pressures inside of cavitation bubbles. Thus the removal efficiency of TOC in BPA was higher than that of phenol. The removal efficiencies of TOC were lower than the degradation efficiencies of phenol and BPA. This result is due to the fact that some intermediates cannot readily degrade during the sonochemical reaction. The H2O2 concentration decreased but was not completely consumed during the sonochemical degradation of pollutants. The initial H2O2 concentration and the physical/chemical characteristics of pollutants were considered to be important factors in determining the formation rate of the H2O2. When high concentration of H2O2 was added to the solution, the formation rates were relatively low compared to when low concentrations of H2O2 were used. (C) 2014 Elsevier B.V. All rights reserved.