Kinetics of hydrazinium nitrate decomposition in nitric acid solutions under the effect of power ultrasound

The effect of ultrasound (f = 20 kHz) on the decomposition of hydrazinium n itrate was investigated in a nitric acid medium. The kinetics of NH2H5+ dec omposition and initial HN3 formation increase in a linear manner with the H NO3 concentration (from 1 to 6 M) and with the ultrasonic intensity (from 0 .5 to 3.1 W cm(-2)). Both rates were equal to that of HNO2 formation in the absence of N2H5+, indicating that the N2H5+ decomposition mechanism is the same as observed without ultrasound between HNO2 and N2H5+. The variation of the steady-state HN3 concentration with the HNO3 concentration and the u ltrasonic intensity suggests the existence of a nonexplosive HN3 thermal de composition mechanism in the cavitation bubble under the effect of ultrasou nd. It was also observed at ultrasonic intensities exceeding 3.5 W cm(-2) t hat the decomposition of HN3 led to the accumulation of NH4+ in solution. ( C) 2001 Elsevier Science B.V. All rights reserved.