Limitations of the methyl radical recombination method for acoustic cavitation bubble temperature measurements in aqueous solutions

The methyl radical recombination (MRR) method has been used for the measurement of cavitation bubble temperatures in aqueous solutions containing a select group of aromatic hydrocarbons as the source for the methyl radicals. The aromatic solutes used were phenol, aniline, m-cresol, and o-toluidine. The maximum bubble core temperatures determined using aniline and phenol were observed to be comparatively high with respect to other reported literature methods and also where the methyl radicals were produced from the cavitation thermolysis of simple aliphatic alcohols. It is concluded that the MRR method cannot be used with organic compounds that do not predominantly produce methyl radicals on the thermal decomposition of the hydrocarbon solutes within the hot core of a collapsing bubble.