Hydroxyl Radical Generation and Contaminant Removal from Water by the Collapse of Microbubbles Under Different Hydrochemical Conditions

Wang, Wanting; Wang, Fan; Huo, Mingxin; Zhao, Hang; Lü, Ying

doi:10.1007/s11270-018-3745-x

Cited by 50 publications

(39 citation statements)

References 25 publications

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“…In other words, only a few molecules of O radicals could be formed per 10 7 dissolving oxygen bubbles. It means that the OH radicals detected in the experiments [71][72][73][74][75]77,78] could not be originated from dissolving bubbles. It should be noted, however, that the accuracy of the present numerical simulations is not high because the Knudsen number, which is the instantaneous mean free path of a gas molecule inside a bubble divided by the instantaneous bubble radius, becomes considerably larger than 0.1 (Figure 9e).…”

Section: Radical Production During Bubble Dissolutionmentioning

confidence: 93%

“…In many of the experiments [71][72][73][74][75]77], OH radicals were detected after stopping cavitation. In the absence of solutes, the lifetime of OH radicals in liquid water is determined by the following reaction.…”

Section: Radical Production During Bubble Dissolutionmentioning

confidence: 99%

“…According to Henglein [85], the local concentration of OH radicals that reach the liquid phase from the interior of a cavitation bubble is experimentally estimated as 5 × 10 −3 M. As the rate constant for reaction (2) at room temperature is 1 × 10 10 M −1 s −1 [114], the lifetime of OH radicals around a cavitation bubble is estimated as 20 ns [64]. Accordingly, OH radicals detected after stopping cavitation [71][72][73][74][75]77] should not be produced during cavitation but produced after stopping cavitation. In the present subsection, the possibility of OH radical production during dissolution of a bubble is discussed based on the results of numerical simulations [115][116][117].…”

Section: Radical Production During Bubble Dissolutionmentioning

confidence: 99%

“…In relation to the generation of OH radicals from UFB water, the generation of OH radicals from microbubble water has also been experimentally reported [77,78]. Wang et al [77] reported that OH radicals were detected using the fluorescence probe APF from microbubble water during microbubble generation using a microbubble generator, consisting of high-speed rotation and compression-dissolution processes. OH radicals were also detected after stopping the microbubble generation for about 20 min [77].…”

Section: Introductionmentioning

confidence: 99%

“…Wang et al [77] reported that OH radicals were detected using the fluorescence probe APF from microbubble water during microbubble generation using a microbubble generator, consisting of high-speed rotation and compression-dissolution processes. OH radicals were also detected after stopping the microbubble generation for about 20 min [77]. Arrojo et al [78] experimentally reported that OH radicals were detected by circulating 30 L of a 250 ppm salicylic acid solution through a cavitation loop with a Venturi tube.…”

Section: Introductionmentioning

confidence: 99%

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On Some Aspects of Nanobubble-Containing Systems

Yasui

2022

Nanomaterials

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Theoretical studies are reviewed for bulk nanobubbles (ultrafine bubbles (UFBs)), which are gas bubbles smaller than 1 μm in diameter. The dynamic equilibrium model is discussed as a promising model for the stability of a UFB against dissolution; more than half of the surface of a UFB should be covered with hydrophobic material (impurity). OH radicals are produced during hydrodynamic or acoustic cavitation to produce UFBs. After stopping cavitation, OH radicals are generated through chemical reactions of H2O2 and O3 in the liquid water. The possibility of radical generation during the bubble dissolution is also discussed based on numerical simulations. UFBs are concentrated on the liquid surface according to the dynamic equilibrium model. As a result, rupture of liquid film is accelerated by the presence of UFBs, which results in a reduction in “surface tension”, measured by the du Noüy ring method. Finally, the interaction of UFBs with a solid surface is discussed.

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Section: Radical Production During Bubble Dissolutionmentioning

confidence: 93%

Section: Radical Production During Bubble Dissolutionmentioning

confidence: 99%

Section: Radical Production During Bubble Dissolutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On Some Aspects of Nanobubble-Containing Systems

Yasui

2022

Nanomaterials

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Tunable Gas‐Gas Reactions through Nanobubble Pathway

et al. 2023

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Combustible gas‐gas reactions usually do not spontaneously occur upon mixing without ignition or other triggers to lower the activation energy barrier. Nanobubbles, however, could provide such possibility in solution under ambient conditions due to high inner pressure and catalytic radicals within their boundary layers. Herein, a tunable gas‐gas reaction strategy via bulk nanobubble pathway has been developed by tuning the interface charge of one type of bulk nanobubbles and promoting its fusion and reaction with another, where the reaction‐accompanied size and number concentration change of the bulk nanobubbles and the corresponding thermal effect clearly confirm the occurrence of the nanobubble‐based H2/O2 combustion. In addition, abundant radicals can be detected during the reaction, which is considered to be critical to ignite the gas reaction during the fusion of nanobubbles in water at room temperature. Therefore, the nanobubble‐based gas‐gas reactions provide a safe and efficient pathway to produce energy and synthesize new matter inaccessible under mild or ambient conditions.

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