Correlation between Na* Emission and “Chemically Active” Acoustic Cavitation Bubbles

Sunartio, Devi; Yasui, Kyuichi; Tuziuti, Toru; Kozuka, Teruyuki; Iida, Yasuo; Ashokkumar, Muthupandian; Grieser, Franz

doi:10.1002/cphc.200700426

Cited by 59 publications

(42 citation statements)

References 29 publications

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“…Similar observations have been reported for Na salts and SDS in water [35,36,37,38,39]. The emission of alkali metal lines itself [40,41] is a phenomenon that gives important information on the collapse modalities of the emitting bubbles.…”

Section: Introductionsupporting

confidence: 74%

“…Due to negligible vapour pressure, the metal atoms should be virtually absent in the "pure" bubble interior gas phase before collapse. Reduction of the ions and excitation could only occur either in the hot "liquid shell" of the collapsed bubble [42], or from "injected droplets" of liquid entering the gas phase [43,35,23]. A potential micro spray would (fully or partly) evaporate with subsequent thermolysis, reduction, and excitation of the metal in the heated (and possibly plasma) environment inside the bubble.…”

Section: Introductionmentioning

confidence: 98%

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Sonoluminescence and dynamics of cavitation bubble populations in sulfuric acid

Thiemann

Holsteyns

Cairós

et al. 2017

Ultrasonics Sonochemistry

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The detailed link of liquid phase sonochemical reactions and bubble dynamics is still not sufficiently known. To further clarify this issue, we image sonoluminescence and bubble oscillations, translations, and shapes in an acoustic cavitation setup at 23kHz in sulfuric acid with dissolved sodium sulfate and xenon gas saturation. The colour of sonoluminescence varies in a way that emissions from excited non-volatile sodium atoms are prominently observed far from the acoustic horn emitter ("red region"), while such emissions are nearly absent close to the horn tip ("blue region"). High-speed images reveal the dynamics of distinct bubble populations that can partly be linked to the different emission regions. In particular, we see smaller strongly collapsing spherical bubbles within the blue region, while larger bubbles with a liquid jet during collapse dominate the red region. The jetting is induced by the fast bubble translation, which is a consequence of acoustic (Bjerknes) forces in the ultrasonic field. Numerical simulations with a spherical single bubble model reproduce quantitatively the volume oscillations and fast translation of the sodium emitting bubbles. Additionally, their intermittent stopping is explained by multistability in a hysteretic parameter range. The findings confirm the assumption that bubble deformations are responsible for pronounced sodium sonoluminescence. Notably the observed translation induced jetting appears to serve as efficient mixing mechanism of liquid into the heated gas phase of collapsing bubbles, thus potentially promoting liquid phase sonochemistry in general.

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Section: Introductionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 98%

Sonoluminescence and dynamics of cavitation bubble populations in sulfuric acid

Thiemann

Holsteyns

Cairós

et al. 2017

Ultrasonics Sonochemistry

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“…Previous studies [26,27] have shown that both SL and SC activities originate from two different bubble populations. It was shown that more SL bubbles were generated at the surface of the liquid, whereas the sonochemically active bubbles were observed in a relatively wider area.…”

Section: Wwwchemphyschemorgmentioning

confidence: 99%

Spatial Distribution of Acoustic Cavitation Bubbles at Different Ultrasound Frequencies

et al. 2010

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Images of sonoluminescence, sonophotoluminescence and sonochemiluminescence are recorded in order to semi-quantitatively compare the spatial distribution of the cavitation activity at three different ultrasound frequencies (170 kHz, 440 kHz and 700 kHz) and at various acoustic amplitudes. At all ultrasound frequencies investigated, the sonochemically active cavitation zones are much larger than the cavitation zones where sonoluminescence is observed. Also, the sonochemically active bubbles are observed at relatively lower acoustic amplitudes than that required for sonoluminescence bubbles to appear. The acoustic power required for the observation of the initial cavitation bubbles increases with an increase in the ultrasound frequency. The cavitation bubbles are observed relatively uniformly throughout the reactor at 170 kHz whereas they are located away from the transducer at the higher frequencies used in this study. While these observations highlight the complexities involved in acoustic cavitation, possible reasons for the observed results are discussed.

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“…Figure 2 shows a new result demonstrating the influence of surfactant on the shape of Na line in SL spectra. Earlier it was reported that small amount of surfactant leads to the growth of intensity of Na line, as well as in a case of large concentration of salt [14]. It was also calculated that the thickness of a salt-solution layer of about 16 nm near bubble boundary is enough for explanation of Na line intensity [15].…”

Section: Resultsmentioning

confidence: 99%