Nano bubble—Size dependence of surface tension and inside pressure

Matsumoto, Mitsuhiro; Tanaka, Kenji

doi:10.1016/j.fluiddyn.2007.12.006

Cited by 91 publications

(71 citation statements)

References 14 publications

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“…5(b)). The figure shows that the surface tension for surface nanobubble is also nearly independent on its radius as for bubbles in the bulk solution [26], and is close to the planar value of γ = 0.31 [27] which was calculated from independent MD runs. Note that different from the simple fluid studied here, the curvature effects on surface tension for a more complex fluid, such as water, are non-negligible for small nanobubbles [28].…”

Section: ∂δGnb ∂Rsupporting

confidence: 70%

What experiments on pinned nanobubbles can tell about the critical nucleus for bubble nucleation

et al. 2017

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Abstract. The process of homogeneous bubble nucleation is almost impossible to probe experimentally, except near the critical point or for liquids under large negative tension. Elsewhere in the phase diagram, the bubble nucleation barrier is so high as to be effectively insurmountable. Consequently, there is a severe lack of experimental studies of homogenous bubble nucleation under conditions of practical importance (e.g., cavitation). Here we use a simple geometric relation to show that we can obtain information about the homogeneous nucleation process from Molecular Dynamics studies of bubble formation in solvophobic nanopores on a solid surface. The free energy of pinned nanobubbles has two extrema as a function of volume: one state corresponds to a free-energy maximum ("the critical nucleus"), the other corresponds to a free-energy minimum (the metastable, pinned nanobubble). Provided that the surface tension does not depend on nanobubble curvature, the radius of the curvature of the metastable surface nanobubble is independent of the radius of the pore and is equal to the radius of the critical nucleus in homogenous bubble nucleation. This observation opens the way to probe the parameters that determine homogeneous bubble nucleation under experimentally accessible conditions, e.g. with AFM studies of metastable nanobubbles. Our theoretical analysis also indicates that a surface with pores of different sizes can be used to determine the curvature corrections to the surface tension. Our conclusions are not limited to bubble nucleation but suggest that a similar approach could be used to probe the structure of critical nuclei in crystal nucleation.Bubble nucleation is a very common process but the observation of truly homogenous bubble nucleation is very rare [1]. The reason is that the free-energy barrier for homogenous bubble nucleation tends to be very high (order 10 3 -10 4 eV), except near the critical point (typical T > 0.9T c ) where the surface tension is very low, or under conditions of extreme under-pressure [2]. For this reason, bubble nucleation under less extreme circumstances (e.g., bubble formation in boiling water) is always dominated by heterogeneous nucleation. The rate of heterogeneous nucleation is normally extremely sensitive to the properties of the surface, in particular to the value of the solid-liquid and solid-vapor surface free energies. Hence, normally, heterogeneous bubble nucleation does not provide direct information about the homogenous nucleation process.Supplementary material in the form of a .pdf file available from the Journal web page at http://dx.doi.org/10.1140/epje/i2017-11604-7 a e-mail: df246@cam.ac.uk b e-mail: jd489@cam.ac.uk c e-mail: zhangxr@mail.buct.edu.cnThe situation is very different in the case of welldefined hydrophobic (or, more generally, "solvophobic") nanopores in a hydrophilic ("solvophilic") surface. Inside these pores, vapor may nucleate easily, sometimes even at a pressure where the bulk liquid is still thermodynamically stable. As the pressure of t...

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Section: ∂δGnb ∂Rsupporting

confidence: 70%

What experiments on pinned nanobubbles can tell about the critical nucleus for bubble nucleation

et al. 2017

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“…It seems to us that this contradiction is probably attributed to the empirical equation of state used in the calculation of vapour in Ref. [1]. The empirical equation of state obtained from their MD simulation for bulk vapour can be applied only to the case where the boundary effect can be neglected, while the bubbles in Ref.…”

Section: Explanation Of the Origin Of The Tolman Length Difference Inmentioning

confidence: 99%

“…The empirical equation of state obtained from their MD simulation for bulk vapour can be applied only to the case where the boundary effect can be neglected, while the bubbles in Ref. [1] are so small that the effect of the vapourliquid boundary on the internal vapour in the bubble cannot be neglected. Therefore the empirical equation of state is invalid for the bubbles discussed there.…”

Section: Explanation Of the Origin Of The Tolman Length Difference Inmentioning

confidence: 99%

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Size-dependent surface tension of a cylindrical nanobubble in liquid Ar

2012

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In view of the continued disputes on the fundamental question of whether the surface tension of a vapour bubble in liquid argon increases, or decreases, or remains unchanged with the increase of curvature radius, a cylindrical vapour bubble of argon is studied by molecular dynamics simulation in this paper instead of spherical vapour bubble so as to reduce the statistical error. So far, the surface tension of the cylindrical vapour bubble has not been studied by molecular dynamics simulation in the literature. Our results show that the surface tension decreases with radius increasing. By fitting the Tolman equation with our data, the Tolman length δ = −0.6225 sigma is given under cut-off radius 2.5σ, where σ = 0.3405 nm is the diameter of an argon atom. The Tolman length of Ar being negative is affirmed and the Tolman length of Ar being approximately zero given in the literature is negated, and it is pointed out that this error is attributed to the application of the inapplicable empirical equation of state and the neglect of the difference between surface tension and an equimolar surface.

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“…High pressure around MNBs may lead to hydrate formation (Takahashi 2003). The applicability of Young-Laplace equation is confirmed by molecular dynamics simulation (Matsumoto 2008). MNBs improve the mass transfer effect and oxidation ability of ozone significantly (Chu 2008).…”

Section: Introductionmentioning

confidence: 87%

Remediation of organics contaminated groundwater by ozone micro-nano bubble

Xia

2016

JGS Special Publication

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Nowadays groundwater contamination widely spreads in China. Organic pollutants are of the public concern since they are toxic and with long life cycle, causing considerable remediation cost. The innovative remediation technologies are urgently needed. In this paper, the micro-nano bubbles (MNBs) technology with the ozone oxidation method was proposed, and laboratory tests were conducted for both surface water and groundwater remediation to degrade methyl orange, which was selected as the representative pollutant. In the test, deionized water was used to configure methyl orange solution of certain concentration, then the concentrations of methyl orange were monitored during the treatment process of ozone macro bubbles, oxygen MNBs, and ozone MNBs. Glass beads with the diameter of 4.0-4.5 mm were selected to simulate highly permeable soils, and the concentrations of both methyl orange and the dissolved ozone were measured during groundwater remediation process by ozone MNBs. The results indicated that oxygen MNBs did not degrade methyl orange, while the degradation effect of ozone bubbles was obvious. The degradation effect of ozone MNBs can even be 41 times greater than ozone macro bubbles for polluted surface water. The groundwater remediation tests further verified that ozone MNBs have significant capability in the remediation of organic contaminated subsurface.

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Nano bubble—Size dependence of surface tension and inside pressure

Cited by 91 publications

References 14 publications

What experiments on pinned nanobubbles can tell about the critical nucleus for bubble nucleation

What experiments on pinned nanobubbles can tell about the critical nucleus for bubble nucleation

Size-dependent surface tension of a cylindrical nanobubble in liquid Ar

Remediation of organics contaminated groundwater by ozone micro-nano bubble

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