Sonochemical Efficiency during Single-Bubble Cavitation in Water

Abstract

We investigated nitrite and nitrate ion formation during single-bubble cavitation by realizing stable light emission for more than 30 h. Production yields of nitrite and nitrate ions in water were obtained as a function of irradiation time. The concentrations of nitrate and nitrite ions increased linearly with irradiation time within experimental error, and the molar ratio of nitrate to nitrite ions was about 1:1. The formation rate for these two ions was 3.8 × 10-10 mol·dm-3·min-1, and the number of nitrite or nitrate ions per cycle was estimated as 7.1 × 106.

Relationship between the bubble temperature and main oxidant created inside an air bubble under ultrasound

“…47 It suggests that HNO 2 may play an important role in some sonochemical reactions especially when pH Ͻ 3.3. [48][49][50][51] As seen in Fig. 6͑a͒, an appreciable amount of hydrogen molecule is created inside a bubble when the acoustic amplitude is higher than about 3 bars at 20 kHz.…”

Theoretical study of single-bubble sonochemistry

“…12 In 2002, Didenko and Suslick 27 first measured the yields of nitrite ions, OH radicals, and photons from a single cavitating bubble in water in which air is dissolved under the condition of single-bubble sonoluminescence ͑SBSL͒. [31][32][33] In the present study, numerical simulations of bubble oscillation under the experimental condition of Didenko and Suslick 27 have been performed taking into account the effect of nonequilibrium chemical reactions inside a bubble and that of nonequilibrium evaporation and condensation of water vapor at the bubble wall. [28][29][30] A SBSL bubble repeats expansion and contraction according to the pressure oscillation of an ultrasonic wave and emits light at each strong collapse like a clock with the period of an ultrasonic wave.…”

Morphology control of CuO micro‐particles using Zn2+ ion and ultrasonic treatment

“…Firstly, the application of an acoustic field produces interfacial waves which become unstable, eventually resulting in the breakage of the water interlayer around the ions. Secondly, the application of low frequency ultrasound causes acoustic cavitation, which is reported to provide extreme temperature and pressure in local area [21] around the particulate. Here, ultrasonic pretreatment changed not the reaction direction, but the reaction rate.…”

“…Then, Zn 2+ ions are embedded in the precursor precipitated from the mixed solution. The precipitation adsorbs Zn 2+ but does not trigger the heterogeneous nucleation of mixed coprecipitation according to Soler-Illia' report [21]. During the hydrothermal reaction, Zn 2+ ions are dissolved into the solution, replaced by Cu 2+ ions to form the crystal lattice.…”

“…Here, Zn 2+ ion is chosen for that Cu and Zn have the similar ionic radius and relative crystallization habit. Ultrasonic is also introduced to test its influence on the crystal growth of the CuO, since it is believed that the application of low frequency ultrasound causes acoustic cavitations, which is reported to provide extreme temperature and pressure around the particles and destroy the stable water layer around ions [20]. During our experimental process, novel tomato-shaped copper oxide crystal has been fabricated by a simple hydrothermal method with the combination effects of ultrasonic pretreatment and the presence of Zn 2+ ion.…”