A Deliberation on Nanobubbles at Surfaces and in Bulk

Seddon, James Richard Thorley; Lohse, Detlef; Ducker, William A.; Craig, Vincent S. J.

doi:10.1002/cphc.201100900

Cited by 179 publications

(184 citation statements)

References 76 publications

(114 reference statements)

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“…We obtained the value of 141.1±1.7 degrees as measured from water side for most cases. This is significantly larger than the contact angle of water droplet at ambient pressure of 85.1±1.5 degrees as shown in Table 3 by same cylindrical shape but is much close to the reported nanobubble contact angle values (~150 degrees) by the AFM experiments 22,50,55,56 .…”

Section: Contact Angle Of Cylindrical Gas Domain At Water-graphite Insupporting

confidence: 87%

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Origin of Interfacial Nanoscopic Gaseous Domains and Formation of Dense Gas Layer at Hydrophobic Solid–Water Interface

2013

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Interfacial gas enrichment (IGE) covering the entire area of hydrophobic solid-water interface has recently been detected by atomic force microscopy (AFM) and hypothesized to be responsible for the unexpected stability and anomalous contact angle of gaseous nanobubbles, and the significant change from DLVO to non-DLVO forces. In this paper, we provide further proof of the existence of IGE in the form of a dense gas layer (DGL) by molecular dynamic simulation.Nitrogen gas adsorption at the water-graphite interface is investigated using molecular dynamic simulation at 300 K and 1 atm normal pressure. The results show that a DGL with a density equivalent to a gas at pressure of 500 atm is formed and equilibrated with a normal pressure of 1 atm. By varying the number of gas molecules in the system, we observe several types of dense gas domains: aggregates, cylindrical cap gas domains and DGLs. Spherical cap gas domains form during the simulation but are unstable and always revert to another type of the gas domains.Furthermore, the calculated surface potential of the DGL-water interface, -17.5 mV, is significantly closer to 0 than the surface potential, -65 mV, of normal gas bubble-water interface. This result supports our previously stated hypothesis that the change in surface potential causes the switch from repulsion to attraction for an AFM tip when the graphite surface is covered by an IGE layer. The change in surface potential comes from the structure change of water molecules at the DGL-water interface as compared with the normal gas-water interface. In addition, the contact angle of the cylindrical cap high density nitrogen gas domains is 141degrees. This contact angle is far greater 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 than 85 degrees observed for water on graphite at ambient conditions and much closer to the 150 degrees contact angle observed for nanobubbles in experiments.

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Section: Contact Angle Of Cylindrical Gas Domain At Water-graphite Insupporting

confidence: 87%

“…Seddon et al 22 provided an extensive review on the contamination layer and dynamic equilibrium models. For the high density gas bubble and contact line pining models, it is hypothesized that very slow gas diffusion results in the long life of nanoscopic gas domains.…”

Section: Introductionmentioning

confidence: 99%

Origin of Interfacial Nanoscopic Gaseous Domains and Formation of Dense Gas Layer at Hydrophobic Solid–Water Interface

2013

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“…The dewetting transition should be sensitive to a small amount of a solute (hydrophobic one for water) [17]. Bridging of two closely separated walls or colloidal particles by bubbles is also of great importance [14,16,17]. (2) In our analysis, the solute is mildly adsorbed at the interface due to a minimum of ν s (n 1 ) in Eq.…”

Section: Summary and Remarksmentioning

confidence: 93%

Density functional theory of gas–liquid phase separation in dilute binary mixtures

Okamoto

Ōnuki

2016

J. Phys.: Condens. Matter

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We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference in the solvation chemical potential ∆µs between liquid and gas is considerably larger than the thermal energy kBT for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by an amount equal to the solute density in liquid multiplied by the large factor kBT exp(∆µs/kBT ). As a result, phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, while the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing the interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

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“…These nanobubbles appear to be stable for very long times, of the order of days to months. Yet as Seddon et al explain in this issue, [46] such bubbles should not exist at all, according to the classical view of the air-water interface, since their small radius of curvature implies a high Laplace pressure inside the bubble that should drive gas diffusion across the interface and cause the bubbles to dissolve almost instantly. If the structures seen in microscopy truly do correspond to bubbles filled with bulklike gas-and this is still not universally accepted [47] -then evidently something is amiss with this reasoning.…”

Section: The Problem With Nanobubblesmentioning

confidence: 98%

Nanobubbles are not a Superficial Matter

Ball¹

2012

ChemPhysChem

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A Deliberation on Nanobubbles at Surfaces and in Bulk

Cited by 179 publications

References 76 publications

Origin of Interfacial Nanoscopic Gaseous Domains and Formation of Dense Gas Layer at Hydrophobic Solid–Water Interface

Origin of Interfacial Nanoscopic Gaseous Domains and Formation of Dense Gas Layer at Hydrophobic Solid–Water Interface

Density functional theory of gas–liquid phase separation in dilute binary mixtures

Nanobubbles are not a Superficial Matter

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