Basic Characterization of Nanobubbles and their Potential Applications

Oshita, Seiichi; Uchida, Tsutomu

doi:10.1002/9781118451915.ch29

Cited by 9 publications

(10 citation statements)

References 31 publications

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“…For example, Ljunggren and Eriksson [5] calculated that the lifetime of an air bubble with radii between 10 and 100 nm ranges from about 1 to 100 s. This short lifetime seems contradictory to experimental results showing that MNBs in water have physiological-activity-promoting or sterilization effects [1,6]. This contradiction has not been resolved because we lack the experimental techniques for observing MNBs dispersed in liquid and for measuring the pressure P g in MNBs.…”

Section: Introductionmentioning

confidence: 42%

“…Here we use the term micro-and nano-bubbles (MNBs) to include all diameters less than several micrometers. MNBs have recently attracted considerable attention as a functional material for industrial applications, such as wastewater purification, water-quality improvement, sterilization, decolorization, and the promotion of the physiological activities of living organisms [1]. These applications are based on the unique properties of MNBs.…”

Section: Introductionmentioning

confidence: 99%

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Generation of micro- and nano-bubbles in water by dissociation of gas hydrates

Uchida

Yamazaki

Gohara

2016

Korean J. Chem. Eng.

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Gas hydrate crystals have a structure in which one molecule is enclathrated in a cage of water molecules.When such a crystal dissociates in water, each enclathrated molecule, generally vapor at standard temperature and pressure, directly dissolves into the water. After the solution is supersaturated, excess gas molecules from further dissociation would start forming small bubbles called micro-and nano-bubbles (MNBs). However, it is difficult to identify such small bubbles dispersed in liquid because they are smaller than a microscope's optical resolution. To confirm the formation of MNBs after gas hydrate dissociation, we used a transmission electron microscope (TEM) to analyze freeze-fracture replicas of CH 4 -hydrate dissociation solution. The TEM images indicate the existence of MNBs in the solution, with a number concentration similar to that from a commercially supplied generator. Raman spectroscopic measurements on the CH 4 -hydrate dissociated solution were then done to confirm that the MNBs contain CH 4 vapor, and to estimate experimentally the inner pressure of the CH 4 MNBs. These results suggest that the dissociation of gas hydrate crystals in water is a simple, effective method to obtain MNB solution. We then discuss how such MNBs may play a key role in the memory effect of gas-hydrate reformation. KeywordsMicrobubble, Nanobubble, gas hydrate dissociation, freeze fracture replica, bubble pressure, memory effect 2

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Section: Introductionmentioning

confidence: 42%

Section: Introductionmentioning

confidence: 99%

Generation of micro- and nano-bubbles in water by dissociation of gas hydrates

Uchida

Yamazaki

Gohara

2016

Korean J. Chem. Eng.

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“…UFBs are small gas bubbles <1 µm (ISO 20408-1:2017(ISO 20408-1: , 2017). They have unique properties such as low buoyancy, high internal pressure, and a low rate of coalescence due to repulsive forces from their negative surface charges (ζ-potential) (Takahashi, 2005;Seddon et al, 2012;Oshita and Uchida, 2013). These properties allow UFBs to remain in the liquid for a long time.…”

Section: Introductionmentioning

confidence: 99%

Contribution of Ultra-Fine Bubbles to Promoting Effect on Propane Hydrate Formation

et al. 2020

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To investigate experimentally how ultra-fine bubbles (UFBs) may promote hydrate formation, we examined the formation of propane (C 3 H 8 ) hydrate from UFB-infused water solution using two preparation methods. In one method, we used C 3 H 8 -hydrate dissociated water, and in the other, C 3 H 8 -UFB-included water prepared with a generator. In both solutions, the initial conditions had a UFB number density of up to 10 9 mL −1 . This number density decreased by only about a half when stored at room temperature for 2 days, indicating that enough amount of UFBs were stably present at least during the formation experiments. Compared to the case without UFBs, the nucleation probabilities within 50 h were ∼1.3 times higher with the UFBs, and the induction times, the time period required for the bulk hydrate formation, were significantly shortened. These results confirmed that UFB-containing water promotes C 3 H 8 -hydrate formation. Combined with the UFB-stability experiments, we conclude that a high number density of UFBs in water contributes to the hydrate promoting effect. Also, consistent with previous research, the present study on C 3 H 8 hydrates showed that the promoting effect would occur even in water that had not experienced any hydrate structures. Applying these findings to the debate over the promoting (or "memory") effect of gas hydrates, we argue that the gas dissolution hypothesis is the more likely explanation for the effect.

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“…Small gas bubbles have great potential in industrial applications such as the purification of wastewater, water-quality improvement, sterilization, decolorization, and the promotion of physiological activities of living organisms [ 1 ]. These bubbles include micrometer-scale bubbles, or microbubbles (MBs), as well as nanometer-scale bubbles, or nanobubbles (NBs).…”

Section: Introductionmentioning

confidence: 99%

“…According to Stoke’s law, a smaller bubble has a smaller rising speed and thus tends to stay longer at a specific area in fluid. Such behavior may explain the observed promotion of physiological activity and sterilization effect of water containing MNBs [ 1 , 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of NaCl on the Lifetime of Micro- and Nanobubbles

et al. 2016

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Micro- and nanobubbles (MNBs) are potentially useful for industrial applications such as the purification of wastewater and the promotion of physiological activities of living organisms. To develop such applications, we should understand their properties and behavior, such as their lifetime and their number density in solution. In the present study, we observed oxygen MNBs distributed in an electrolyte (NaCl) solution using a transmission electron microscope to analyze samples made with the freeze-fracture replica method. We found that MNBs in a 100 mM NaCl solution remain for at least 1 week, but at higher concentrations decay more quickly. To better understand their lifetimes, we compared measurements of the solution's dissolved oxygen concentration and the ζ-potential of the MNBs. Our detailed observations of transmission electron microscopy (TEM) images allows us to conclude that low concentrations of NaCl stabilize MNBs due to the ion shielding effect. However, higher concentrations accelerate their disappearance by reducing the repulsive force between MNBs.

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Basic Characterization of Nanobubbles and their Potential Applications

Cited by 9 publications

References 31 publications

Generation of micro- and nano-bubbles in water by dissociation of gas hydrates

Generation of micro- and nano-bubbles in water by dissociation of gas hydrates

Contribution of Ultra-Fine Bubbles to Promoting Effect on Propane Hydrate Formation

Effect of NaCl on the Lifetime of Micro- and Nanobubbles

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