Improvement of the rate of sono-oxidation in the presence of CO<sub>2</sub>

Harada, Hisashi; Ono, Yumie

doi:10.7567/jjap.54.07he10

Cited by 12 publications

(12 citation statements)

References 32 publications

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“…The product yield was reduced when the mole fraction of CO 2 was increased beyond 3% and then be zero when %CO 2 > 8%. The same optimum of CO 2 (2%) in Ar was recorded by Harada and Ono for the sono‐oxidation of KI at various combinations of frequencies and powers (28 kHz and 100 W, 200 kHz and 100 W, 200 kHz and 15 W, 2.4 MHz and 15 W). In the work of Harada and Ono, the oxidation yield at 2.4 MHz drops quickly at 5% CO 2 and falls to zero for %CO 2 > 20%.…”

Section: Resultssupporting

confidence: 68%

Toward understanding the mechanism of pure CO₂‐quenching sonochemical processes

Merouani¹,

Hamdaoui

Al‐Zahrani

2019

J of Chemical Tech & Biotech

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BACKGROUND: Carbon dioxide (CO 2 ) is a gas that has a distinguished effect on the sonochemical process. Dissolving pure CO 2 in solutions prevented sonochemical action in all laboratory-scale experiments, reported until know. The mechanism underlying the pure-CO 2 nullifying sonochemical treatment is until now under debate. RESULTS: Herein, thanks to confronting detailed numerical simulation results for single bubble sonochemistry with literature experimental observations, the mechanism of pure CO 2 -quenching sonochemical reaction was clarified. The acoustic generation of free radicals under CO 2 atmosphere was simulated for different conditions of frequency (20−1100 kHz), acoustic power (0.5−1 W cm -2 ), liquid temperature (20−50 ∘ C) and external pressure (0.6−1.6 atm) and compared with that generated for air-saturation, for the same conditions. Depending on the sonochemical parameters, it was found that CO 2 may enhance, decrease or completely suppress the acoustic generation of hydroxyl radicals. The effect of CO 2 was strongly operating conditions-dependent. CONCLUSION: Given that CO 2 nullified all sonolytic actions in aqueous solution, it was concluded that owing to its very high solubility in water (46-fold much higher than that of air), CO 2 could suppress the inertial cavitation bubbles responsible of all chemical actions. Gases of too higher solubility could favor the bubble-bubble coalescence rather than the production of inertial cavitation bubbles. The bubble-bubble coalescence in this case could be a suppressor of inertial cavitation. A high extent of bubbles coalescence could take place under CO 2 saturation provoking total disappearance of the chemical activity. Greek lettersSpecific heat ratio (c p /c v ) of the gas mixture. Surface tension of liquid water (N m -1 ). Density of liquid water (kg m -3 ).

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Section: Resultssupporting

confidence: 68%

Toward understanding the mechanism of pure CO₂‐quenching sonochemical processes

Merouani¹,

Hamdaoui

Al‐Zahrani

2019

J of Chemical Tech & Biotech

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“…These findings may be understood by considering CO 2 to be a radical scavenger, that is, if CO 2 quenches •H, then •OH will remain and oxidise the reactants. This is shown in reactions (17) and (18) which are those that occur under Ar in water, reactions (19) and (20) show how •OH contributes to oxidation while •H is consumed by the CO 2 [95].…”

Section: Gas Mixturesmentioning

confidence: 93%

“…Henglein in an earlier paper also considered that CO 2 amounts greater than 3% resulted in decreased sonochemical yields [221]. In another other study, it was concluded that the effect of small amounts of CO 2 in argon at 200 kHz and 100 W can lead to an increase I ି production up to seven fold [95]. These findings may be understood by considering CO 2 to be a radical scavenger, that is, if CO 2 quenches •H, then •OH will remain and oxidise the reactants.…”

Section: Gas Mixturesmentioning

confidence: 96%

“…In general an increase in pressure amplitude will relate directly to the power transferred to the liquid and, up to a point, increase the number of cavitation bubbles, the temperature of collapse and the sonochemical yield [16,95,121]. There are upper and lower limits of pressure amplitude to the cavitation threshold [16].…”

Section: Pressure Amplitudementioning

confidence: 99%

“…For large amounts of CO 2 there is inhibition of radical production, however small amounts in Ar, He, O 2 , N 2 have been found to improve sonochemical rates [95,221,223,268]. Sonochemical oxidation (of I ି ions) reduces significantly above 3% CO 2 in air, as does the sonochemical reduction of the carbon dioxide present which in atmospheres other than air follows the order Ar > He > H 2 > N 2 [223,268].…”

Section: Gas Mixturesmentioning

confidence: 99%

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A parametric review of sonochemistry: Control and augmentation of sonochemical activity in aqueous solutions

Wood

Lee

Bussemaker

2017

Ultrasonics Sonochemistry

260

137

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Please cite this article as: R.J. Wood, J. Lee, M.J. Bussemaker, A parametric review of sonochemistry: control and augmentation of sonochemical activity in aqueous solutions, Ultrasonics Sonochemistry (2017), doi: http:// dx.doi.org/10. 1016/j.ultsonch.2017.03.030 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A parametric review of sonochemistry: control and augmentation of sonochemical activity in aqueous solutions

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