The hydroxyl radical (OH•) is a powerful oxidant produced as a consequence of cavitation in water. It can react nonspecifically in
breaking down persistent organic pollutants in water into their mineral form. It can also recombine to form hydrogen peroxide which is
very useful in water treatment. In this study, terephthalic acid (TA) and potassium iodide dosimetry were used to quantify and investigate
the behaviour of the generated OH radical in a laboratory scale sonicator. The 2-hydroxyl terephthalic acid (HTA) formed during
terephthalic acid dosimetry was determined by optical fibre spectrometer. The production rate of HTA served as a means of evaluating and
characterizing the OH• generated over given time in a sonicator. The influence of sonicator power intensity, solution pH and irradiation
time upon OH• generation were investigated. Approximately 2.2 x 10-9 M s-1 of OH radical was generated during the sonication process.
The rate of generation of the OH radicals was established to be independent of the concentration of the initial reactant. Thus, the rate of
generation of OH• can be predicted by zero order kinetics in a sonicator.