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The introduction of ultrasonic vibrations into aqueous solutions can, under certain conditions, lead to the emergence of cavitation, which is expressed in the emergence and collapse of vapor-gas bubbles. In this case, the relatively low average energy of ultrasonic vibrations is concentrated in a small volume of vapor-gas bubbles, reaching high values. As a result, high temperatures (on the order of several thousand degrees) and high pressures (hundreds of atmospheres) are realized inside the vapor-gas bubbles. In a number of cases, processes that are impossible under normal conditions may occur.
The study of the effect of ultrasound on an aqueous solution of potassium iodide was carried out at ultrasound frequencies ν = 22 and 44 kHz. The development of the process was monitored by the amount of molecular iodine accumulating in the solution.
It was shown that when an aqueous solution of potassium iodide was exposed to ultrasound radiation, it was found that if cavitation occurs, the I- ions are reduced to molecular iodine. In this case, the process of iodine release occurs in an oscillatory mode. It has been shown that the rate of iodine release and its maximum concentration depend on the ultrasound intensity, the concentration of potassium iodide solution and the ultrasound frequency. Moreover, increasing the concentration of potassium iodide in the initial solution above 5-6% does not lead to a further increase in the concentration of the formed iodine. The dependence of the maximum iodine concentration on the amplitude of the waveguide end oscillations is nonlinear and average rate of accumulation in the solution of molecular iodine is maximum at an oscillation amplitude of the waveguide end of 17-24 mkm.
