Diffusion coefficients for helium, hydrogen, and carbon dioxide in water at 25°C

Mazarei, Abbas F.; Sandall, Orville C.

doi:10.1002/aic.690260128

Cited by 53 publications

(18 citation statements)

References 18 publications

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“…The difference in the assumptions of the two theories yields a prediction of approximately a factor of two slower dissolution for the "negative feedback" model of a pinned bubble relative to the "positive feedback" model of a hemispherical bubble. Both models predict that N 2 bubbles will have lifetimes ∼3 times longer than a H 2 bubble of the same size based upon the difference in dissolved gas diffusion coefficients (1.9 × 10 −5 cm 2 /s and 4.5 × 10 −5 cm 2 /s for N 2 and H 2 , respectively) 36,37 and difference in gas solubility (0.69 mM/atm and 0.8 mM/atm for N 2 and H 2 , respectively).…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Measurement of Hydrogen and Nitrogen Nanobubble Lifetimes at Pt Nanoelectrodes

German

Chen

Edwards

et al. 2016

J. Electrochem. Soc.

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The lifetimes of individual H 2 and N 2 nanobubbles, electrochemically generated at Pt nanoelectrodes (7-85 nm-radius), have been measured using a fast-scan electrochemical technique. To measure lifetime, a stable single H 2 or N 2 bubble is first generated by reducing protons or oxidizing hydrazine, respectively, at the Pt nanoelectrode. The electrode potential is then rapidly stepped (<100 μs) to a value where the bubble is unstable and begins to dissolve by gas molecule transfer across the gas/water interface and diffusion. The electrode potential is immediately scanned back to values where the bubble was initially stable. Depending on the rate of this second voltammetric scan, the initial bubble may or may not have time to dissolve, as is readily determined by the characteristic voltammetric signature corresponding to the nucleation of a new bubble. The transition between these regimes is used to determine the bubble's lifetime. The results indicate that dissolution of a H 2 or N 2 nanobubble is, in part, limited by the transfer of molecules across the gas/water interface. A theoretical expression describing mixed diffusion/kinetic control is presented and fit to the experimental data to obtain an interfacial gas transfer rate of ∼10 Interfacial nanobubbles are gaseous, nanoscale spherical caps on a solid substrate immersed in a gas-saturated solution. They were first proposed to explain the long-range attractive interactions between hydrophobic surfaces.1-3 Initially their existence was contentiously debated, 4,5 but their existence, composition and stability has since been documented in numerous experiments. [6][7][8][9][10] The argument against their existence is due to the lack of a theoretical understanding of their peculiar longevity, often measured in days. 11It is well understood that a spherical bubble suspended in a gassaturated liquid should be intrinsically unstable. The internal pressure within a bubble of radius R exceeds that of its surroundings by the Laplace pressure, 2γ/R, where γ is the liquid's surface tension. The gas within the bubble therefore has a higher chemical potential than the dissolved gas and must reach equilibrium by dissolution into the liquid and transport away from the bubble. While this process is quite slow for macroscopic bubbles, the rate of dissolution increases by orders of magnitude for nanoscopic bubbles, due to the increase in Laplace pressure and decreased diffusion lengths. Epstein and Plesset 12 first detailed a theoretical framework for growing and shrinking bubbles and later Ljunggren and Eriksson 13 explicitly extended the theory to the nanoscale. Both mathematical approaches predict isolated, spherical bubbles smaller than 100 nm radius to dissolve in less than 100 microseconds. Experimentally, and as noted above, nanobubbles are observed to persist for much longer periods, often for several days. 11Several different mechanisms have been proposed to explain the persistence of nanobubbles on surfaces: a transport barrier and lowering of the surface tension b...

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Section: Resultsmentioning

confidence: 99%

Electrochemical Measurement of Hydrogen and Nitrogen Nanobubble Lifetimes at Pt Nanoelectrodes

German

Chen

Edwards

et al. 2016

J. Electrochem. Soc.

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“…Thus, the attained maximum rate of the reduction process is attributed to: (i) the high concentration of H þ (pHB4) in the reaction media and (ii) the low viscosity of the solution. It is clear that the low viscosity allows for a high diffusion rate of the reactants (EMIM-CO 2 À and H þ ) towards the catalyst's active edge sites 27,[32][33][34] . A similar trend was observed for Ag NPs catalysts in a dynamic electrochemical flow cell when the maximum current density (B8 mA cm À 2 ) was obtained in a 90 mol% water electrolyte 13 .…”

Section: Resultsmentioning

confidence: 99%

Robust carbon dioxide reduction on molybdenum disulphide edges

et al. 2014

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“…We conducted a survey of literature diffusion coefficients of CO 2 H 2 O mixtures and found 187 data points 9–44. Table 1 presents a summary of all CO 2 H 2 O experimental data found in literature.…”

Section: Introductionmentioning

confidence: 99%

Modeling infinite dilution and Fickian diffusion coefficients of carbon dioxide in water

2011

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We propose a new model for calculating infinite dilution diffusion coefficients for carbon dioxide and water mixtures. The model takes into account temperature dependence of the dipole moment of water and polarizability of CO 2 , and fits experimental CO 2 AH 2 O data at low and high pressures with an accuracy of 4.9%. Remarkably, the proposed model also accurately predicts infinite dilution diffusion coefficients for other binary water mixtures where solute polarizability is close to that of CO 2 , such as CH 4 , C 2 H 6 , C 3 H 8 , and H 2 S. Moreover, we present-to the best of our knowledge-the first predictions of composition-based Fickian diffusion coefficients for CO 2 AH 2 O mixtures over the temperature range 298.15-413.15 K, and pressures up to 50 MPa.

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Diffusion coefficients for helium, hydrogen, and carbon dioxide in water at 25°C

Cited by 53 publications

References 18 publications

Electrochemical Measurement of Hydrogen and Nitrogen Nanobubble Lifetimes at Pt Nanoelectrodes

Electrochemical Measurement of Hydrogen and Nitrogen Nanobubble Lifetimes at Pt Nanoelectrodes

Robust carbon dioxide reduction on molybdenum disulphide edges

Modeling infinite dilution and Fickian diffusion coefficients of carbon dioxide in water

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