Sonolysis of fluoro-, chloro-, bromo- and iodobenzene: a comparative study

The sonolysis at 520 kHz of the four monohalogenated benzenes, fluoro- (FB), chloro- (CB), bromo- (BB) and iodobenzene (IB) at different initial concentrations, 0.5, 1 and 2 mM, was studied. The sonolysis rate of all four compounds depends on the initial concentration. During sonolysis of FB, CB, BB and IB analogous apolar organic degradation products were determined, indicating that all four monohalogenated benzenes degrade following a similar degradation mechanism. The relative yield of the different degradation products was different, as was shown for the degradation product benzene. A previously developed kinetic model was applied to the sonolysis of the monohalogenated benzenes and a good correlation between experimental and simulated concentration versus time profiles was obtained for all four compounds. By comparing the influence of the different monohalogenated benzenes on their own sonolysis rate, it could be deduced that the proportionality between their concentration in the cavitation bubbles and their concentration in the bulk solution depends on their aqueous diffusion coefficient rather than on their Henry's law coefficient.